Industrial Safety

INDUSTRIAL SAFETY

COMPLED BY:

MUHAMMAD SHAMSHAD

(COURSE MATERIAL FOR DEPARTMENTAL PROMOTION EXAMINATION (DPE))

Industrial Safety

Table of Contents Industrial Safety .................................................................................................................................... 4 introduction ................................................................................................................................ 4 DEFINITIONS ........................................................................................................................... 5 Accident ..................................................................................................................................... 5 Unsafe Conditions...................................................................................................................... 6 Process Environmental Hygiene ................................................................................................ 6 GENERAL SAFETY RULES ................................................................................................... 8 Industrial Hazard Permit (IHP) ................................................................................................ 10 safety in Work Areas ............................................................................................................... 10 Identification of Gas Cylinders ................................................................................................ 14 Compressed Gas Cylinders Safety ........................................................................................... 14 Hazards of Entry into Confined Spaces ................................................................................... 15 Electrical Safety Rules ............................................................................................................. 17 Fire ........................................................................................................................................... 18 Hazards of Falls ....................................................................................................................... 18 Hazards of compressed air ....................................................................................................... 19 hazards of Welding .................................................................................................................. 20 Personnel Protective Equipment .............................................................................................. 22 RESPIRATORY PROTECTION ............................................................................................ 27 FIRST AID HINTS .................................................................................................................. 31 Industrial Safety (Electrical Safety) .................................................................................................. 36 Introduction .............................................................................................................................. 36 Electric Shock .......................................................................................................................... 36 GENERAL REQUIREMENTS ............................................................................................... 41 special considerations during electrical works......................................................................... 46 WORKING WITH TEST INSTRUMENTS AND EQUIPMENT .......................................... 57 ELECTRICAL PREVENTIVE MAINTENANCE ................................................................. 58 GROUNDING ......................................................................................................................... 60 SPECIAL OCCUPANCIES..................................................................................................... 68 PREVENTION OF EXTERNAL IGNITION AND EXPLOSION ......................................... 71 Industrial Safety (Fire Protection) .................................................................................................... 74 Fire Protection.......................................................................................................................... 74 Extinguishing the fire............................................................................................................... 74 Preventing Fires ....................................................................................................................... 74

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Industrial Safety

Mechanism of Fire Extinguishment ......................................................................................... 77 Classification of fire................................................................................................................. 78 fire Extinguishers ..................................................................................................................... 79 Use of Fire extinguisher ........................................................................................................... 83 How to Use Extinguishers ....................................................................................................... 86 Installation ............................................................................................................................... 88 Inspection and Testing of Extinguishers .................................................................................. 90 Industrial Safety (Running Nips) ...................................................................................................... 96 DEFINITION ........................................................................................................................... 96 TYPES OF ACCIDENTS ........................................................................................................ 96 CONVEYOR BELT NIPS ....................................................................................................... 97 NIPS BETEEN MATERIALS AND ROLLERS .................................................................... 98 TWO-ROLL MILLS .............................................................................................................. 100 1.1.

WORKING ON BACK ROLLS ................................................................................. 102

CALENDERS ........................................................................................................................ 103 1.2.

FEED NIPS ................................................................................................................. 104

1.3.

OTHER CALENDER NIPS ....................................................................................... 105

SAFETY BY POSITION ....................................................................................................... 108 CONCLUSION ...................................................................................................................... 108 Industrial Safety (Chemicals Safety) ............................................................................................... 110 Purpose................................................................................................................................... 110 Definitions ............................................................................................................................. 110 Storage of Chemicals ............................................................................................................. 110 Handling of Chemicals .......................................................................................................... 117 Handling of some common compounds ................................................................................ 118 GENERAL Safety Rules........................................................................................................ 127 (SAMPLE PAPER) ........................................................................................................................... 131 References .......................................................................................................................................... 133 Further Study .................................................................................................................................... 133

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Industrial Safety

INDUSTRIAL SAFETY INTRODUCTION Industrial Safety, area of safety engineering and public health that deals with the protection of workers' health, through control of the work environment to reduce or eliminate hazards. Industrial accidents and unsafe working conditions can result in temporary or permanent injury, illness, or even death. They also take a toll in reduced efficiency and loss of productivity. Various external sources, such as chemical, biological, or physical hazards, can cause work-related injury. Hazards may also result from the interaction between worker and environment; these so-called ergonomic hazards can cause physiological or psychological stress. Chemical hazards can arise from the presence of poisonous or irritating gas, mist, or dust in the workplace. Hazard elimination may require the use of alternative and less toxic materials, improved ventilation, leakage control, or protective clothing. Biological hazards arise from bacteria or viruses transmitted by animals or unclean equipment and tend to occur primarily in the food-processing industry. The source of the contamination must be eliminated or, when that is not possible, protective equipment must be worn. Common physical hazards include ambient heat, burns, noise, vibration, sudden pressure changes, radiation, and electric shock. Industrial safety engineers attempt to eliminate hazards at their source or to reduce their intensity. If this is impossible, workers are required to wear protective equipment. Depending on the hazard, this equipment may include safety glasses, earplugs or earmuffs, face masks, heat or radiation protection suits, boots, gloves, and helmets. To be effective, however, the protective equipment must be appropriate, properly maintained, and worn by the worker. If the physical, psychological, or environmental demands on workers exceed their capabilities, ergonomic hazards arise. This type of hazard frequently occurs in the area of materials handling, where workers must lift or carry heavy loads. Poor working posture or improper design of the workplace often results in muscle strains, sprains, fractures, bruises, and back pain. These injuries account for 25 percent of all occupational injuries, and their control requires designing the job so that workers can perform it without overexerting themselves.

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Industrial Safety

DEFINITIONS Safety

The apposite of danger?

Hazards

A hazard is a condition with the potential of causing injury or damage.

Danger

Express the degree of exposure to a hazard

Probability

An objective mathematical term having a value between 0 and 1, where 0 represents complete impossibility and 1 represents absolute uncertainty?

Chance

Refers to the probability outcome of some event.

Uncertainty

Exists only in our minds; and has much the same meaning as doubt. Its opposite is often regarded as faith.

Risk

Used for uncertain eventualities. Risk may be classified as speculative or pure.

Frequency Rate

Number of accidents per million man hours worked.

Severity Rate

Number of days lost per million man hours worked.

Minor Injury

Usually those having no permanent effects and leading to less than three days of work lost.

Major Injury

Leading to three or more days of work lost.

of

an

uncertain

ACCIDENT An accident is any unforeseen or unexpected event that may or may not result in an injury or damage to property or equipment. The ultimate goal in accident prevention is zero disabling injuries and no work time lost. However, there are many barriers to achieving this goal, the most important of which is the human attitude. Most people feel that ―it won't happen to me" or "it couldn't happen here". You can do more to protect yourself and your fellow worker by constantly thinking and practicing accident prevention than you can by memorizing all of the rules, regulations and safeguards ever invented or written. You must THINK before you act. Accidents take place only by either or both of two reasons:

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Industrial Safety

Unsafe conditions. Unsafe act. Unsafe conditions are defined as hazards built-in the environment or equipment or machine which has potential to cause accident. These unsafe conditions in industry or most commonly available and can be eliminated with a bit redesigning and putting up a small additional amount of finance. These unsafe conditions are unguarded rotating machines or machine parts, unsafe material handling equipment defective tools, unguarded opening etc.

UNSAFE CONDITIONS Unguarded rotary machines. Unsafe material handling equipment. Defective tools. Unsafe electrical equipments. High working platforms without protection rails. Broken ladders. Slippery floors. Fire hazards. Toxic gases. Enclosed space. High temperature. Radio activity.

UNSAFE ACT Unsafe act is a built-in hazard which is developed by human error, lack of knowledge, lake of training, carelessness etc. Unsafe act on apart of operators / maintainer at plant is to use a wrong tool or to use a tool at wrong place, may be the tool is OK but it will built-up a potential for an accident. Unsafe act can be minimized by education of people, proper training to do a certain job and developing safety awareness and reducing carelessness while on job.

PROCESS ENVIRONMENTAL HYGIENE Poor housekeeping is an industrial hazard and a frequent contributory cause of accidents, often by masking other hazards.

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Industrial Safety

Most safety specialists have a keen eye for good and bad housekeeping, typical features of the latter being poor lighting, dirt and untidiness, with materials, tools and scrap dumped on floor and benches, and no clear gang-ways between machines. Poor housekeeping may constitute a tripping or falling hazards, a fire hazard or dust explosion hazard. In the general disorder the greasy or damaged floor is camouflaged and defective guards, tools, machinery and electric cables appear normal. Good housekeeping requires more than good habits, regular cleaning, washing and maintaining walls, floors, doors, windows; in the first place it requires positive planning. The flow of materials through a process i.e. maintenance / modification must be studied and proper provision made for by-products (offcuts, dust, turnings packing, scaffolding and transient combustible materials) to be segregated, removed and disposed of. The hazards of poor housekeeping are specially acute when the materials left lying about are toxic, flammable or react violently with water. The subject of housekeeping is closely allied to cleaning. Many aspects of both of these are covered by the followings which sets out the basic rules of factory cleanliness. These include: Daily removal of refuse and dirt from floors and benches. Weekly cleaning of workroom floors. Inside ceiling, walls and partitions to be cleaned with hot water at least every fourteen months and painted or varnished at least every seven years. Proper vacuum cleaning equipment with tools for reaching into nooks and corners and adequate and well maintained dust filters are a must for all operations where dust is present. Brooms, brushes, waste for removing floor spillages, cleaning tools and detergents or other cleaning solutions should be provided for use by employees as the job demands. Aisles and gangways must be clearly worked and everyone made aware of the necessity of keeping them clear. Areas where goods may be placed temporarily should be marked. Slipshod and ill-conceived lubrication methods can contribute seriously to bad housekeeping – either through oil spillages or through the discharge of fine oil mist into atmosphere. Specialist advice should be sought where this is a problem. Even the compressed air in many works contains small amounts of finely suspended oil from the compressor.

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Industrial Safety

During daily routine, workers are probably exposed to many voltages that could be deadly. Modern life depends on electricity to run machinery, to provide heat and light, and to do many of the jobs everyone tasks for granted. Handled with care and respect, electricity is safe and useful. But when it is handled with ignorance or disregard for safety, electricity can be a real killer. Ignorance of safety regulations is no excuse for violating them. In fact, one can be fired for doing so. If you are in doubt about he meaning of a rule, ask your supervisor to explain it to you. Every worker should report any defective condition or near accident promptly. The effects of low current on the human body range from a temporary mild tingling sensation to death. An electric shock can injure you in either or both of the following ways. A severe shock can stop the heart or the breathing muscles, or both. The heating effects of the current can cause severe burns, especially at points where the electricity enters and leaves the body. Other effects include severe bleeding, breathing difficulty, and ventricular fibrillation (a condition where the heart does not stop, but contracts irregularly). High potential difference itself never killed anyone. However, it can startle you, causing you to lose your balance and fall. This is especially dangerous if you are standing on a ladder or scaffolding. It is the current that does the damage to the human body. Current depends on the potential difference across a circuit, and on the circuit‘s resistance. The resistance of the human body equals the internal resistance of the body, plus the resistance of the skin and the point of contact.

GENERAL SAFETY RULES Following Industrial safety rules should be observed at the work area Use of Helmet in Helmet area is necessary Use of Safety shoes is necessary. Use of loose cloths should be avoided in all working areas, uniform and dungarees should be used. Use of gloves is necessary for work like grinding, scaffolding, welding, chemicals handling etc. Use of safety glasses/face shield is necessary for welding, flame cutting, grinding etc.

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Industrial Safety

Use of dust filter with half mask is necessary in work area involving dust/radiation / mist. Chemical filter cartridge with half mask should be used in work areas, involving hazardous fumes, Toxic vapors like, painting, chemicals. CO2 filter cartridge shall be used in case smoke / fire Breathing apparatus must be used inside confined space. Use of safety belt is necessary while working at height, Ear muffs must be used in noising areas for ear protection, like turbine hall and Diesel Generator Rooms. Welding, flame cutting, making of fire and grinding must not be allowed without Industrial Hazard permit. Electrical Exit signs boards with the instruction ― Exit‖ must be available that should be used in emergency. Walk-ways, stairs, openings and high rise must be protected by safety railings / lids etc. Many special works involving potential risk like suspended loads of crane throwing of objects from heights etc. should be marked off to protect workers. Marked ropes / masking tapes should be used for this purpose. Good house keeping should be maintained through regular cleaning and removal of refuse. Entrances / Exists, Passages and Corridors should be kept clean clear and unobstructed. Proper lighting should be provided in all the working areas Torches and emergency light should always remain available and within reach. Special care should be taken while passing through slippery areas caused either due to oil spillage or water etc. When handling object manually, consideration should be given to the weight, nature and shape of the object to avoid slipped disc syndrome, injury etc. Protective guards have been fixed around moving parts of machines, like grinding disk and motor belts etc. to protect workers and avoid injury. Gas cylinders i.e. oxygen and acetylene and for welding and flame cutting should be handled properly. Following precaution should be taken:Should be kept in racks in up right position.

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Industrial Safety

Not exposed to sunlight, and pressure above 15 psi. Not taken inside enclosed space i.e. tanks / vessels. Spark is not allowed to be taken near cylinders. Cylinders should not be mixed with others. Empty cylinder should be handled with care and stored out side the plant. H2 cylinders should be stored in closed / separate store provided with forced ventilation and explosion proof lights. Machine should be operated/repaired with proper tools by qualified persons according to procedure and operating manuals. No body should be allowed to enter confined space like, tanks and vessels containing toxic vapors or their exist oxygen deficiency, unless the atmosphere is tested. Area where RT (Radiographic test) is being performed should be shielded and de-marked to avoid exposure to radiation. While working near electrical circuit do not wear, rings, watches, metal jewelry, metal hand hats etc. Use rubber sole shoes / Rubber insulated gloves. Insulated and explosion proof electrical tools should be used while working on electric circuits and machines. Do not hang clothes over electric panel and switchgear. While making repair of electrical circuits and machines main power shall be switched off.

INDUSTRIAL HAZARD PERMIT (IHP) If you are working in an industry or an industrial environment, there will be some industrial hazard permit that permits work involving potential safety hazards. It is necessary to obtain Industrial Hazard Permit for every specific hazardous job. Personal protective measures and precaution are written on the IHP for the Industrial Hazards connected with the execution of the job. Before start of the job, protective measures as specified may be adopted. If requirement of safety is not fulfilled, the job can be stopped by the Industrial Safety staff. SAFETY IN WORK AREAS Good housekeeping is an essential part of every job. Work areas, walkways and equipment shall be kept clear of loose materials, tools and scraps.

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Industrial Safety

Materials such as pipe and lumber shall be stored in an orderly and secure manner. Spills such as grease, water or oil shall be cleaned up as soon as possible; a delay could result in an accident to you or a fellow worker. A safe access shall be maintained to work areas. short cuts should be avoided. Never block fire exits with equipment or materials.

PROPER LIFTING The practice of stooping over from the waist to lift, accompanied with the added factors of uneven footing, poor balance or awkward positioning is a direct invitation to eventual injury, because undue strain is thrown on the back and abdominal muscles. The following rules should be followed for safe lifting: Determine if you need help-- consider the distance and the object's weight. Look over the pick-up and delivery area for tripping hazards, slippery spots, small doors, sharp corners, blind spots, etc. Inspect the object for sharp corners, wet surfaces, etc. Place feet correctly--one foot close to the side of the object to provide stability-and one directly behind the object to provide lift or thrust. Keep the object close to your body. Get a correct grip or hold on the object by using a full grip--not just your fingers. Keep your back straight--this does not mean vertical--just aligned from head to pelvis. You should tuck in your chin when lifting to ensure alignment from head to pelvis. Do the actual lifting with your legs only. You should lower objects in the same manner as you lifted them. The body should never be turned or twisted while under the stress of heavy weight. Instead, you should turn your whole body if you desire to change your position after you have made the lift.

LADDERS

AND

SCAFFOLDING

Although there is always a risk in working on elevated areas, it is a fact that the vast majority of accidents involving ladders result from the failure to exercise care. Carry ladders parallel to the ground.

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Industrial Safety

Whenever possible, angle out the base one-fourth of the ladder's working length. The ladder should reach at least three feet six inches above the landing. Never stand on the top two steps of any ladder or on the top cap of a step ladder. This could cause you to become off-balance resulting in a fall. Always maintain at least three points of contact with the ladder (2 feet and 1 hand, or 2 hands and 1 foot should be in contact with the ladder at all times). Maintain ladders free of oil, grease and other hazards. Either ladders should be properly lashed near to their upper resting place in order to prevent side ways movement or must be secured at or near their lower end or some body must foot the ladder whilst it is in use. It must have firm and level footing. Scaffolding shall be used if solid footing or a safe ladder is not available. Before erecting scaffolding it is necessary to prepare the ground which is to be the base. The ground must be leveled off and compacted. Sole-plates (bulk timber) acting as bearers should then be placed in position to receive the standard (scaffolding pipes) On sole plates base plates should be placed and fixed at proper positions. The span between standard should never be greater than 2.1m. They may be placed closer according to the load the scaffolds have to carry. All standard should be in vertical position. All ledgers should be horizontal and clamped to standard with right angled couplers. Fall of persons from height can be prevented if scaffolds and working place are properly protected by the provision of guard-rail and toe board Use only non-conductive side rails around live electrical equipment. Wear protective clothing and rubber soled shoes. It is your responsibility to keep all tools and materials away from the edges of the scaffold and platform openings Sufficient help shall be used to move the scaffold. A "watcher" shall be posted for overhead obstructions as well as holes, etc. at ground level.

REQUIREMENTS

OF

SAFE RIGGING OPERATION

Staff shall do their best in the following:

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Industrial Safety

Concentration on work. Good communication between operator and ground. Checking equipment prior to use. Fastening. Stable lifting. Unified commanding. Rigging operation should not be allowed to start if any of the following conditions exist: Lifting rope is slanting. Crane is overloaded. Bulk is too full in container. Lifted goods are not fastened securely. Commanding signal is not clear. There is no prevention measure against sharp edge of lifted goods. There is person on the lifted goods. Structural parts being buried under ground. Crane is out of order. It is too dark to see lifted goods There is no prevention measure against strong wind.

SAFE OPERATION

OF

LIFTING MACHINERY

AND

TACKLES

Thorough examination of Cranes and lifting Tackle suspended from the Crane hook should be performed before operation. The parts to be examined include Crane Wheels, Crawler tracks, load hook, chains, ropes, tackle etc. All these parts should be in good working condition. Any defect found/observed should be immediately reported to the Incharge/Supervisor for corrective action.

ELECTRIC OVER

HEAD TRAVELING

CRANE

The crane should be operated only by qualified persons authorized by the competent authority. The operator should be medically fit. He should follow instruction for safe operation of the Crane contained in the manual provided to him. Electric overhead Cranes should only be used for making direct lifts and should not be used for dragging loads from bays on either side of the Crane tack, this

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Industrial Safety

can cause the load ropes to leave the hoist barrel grooves. A subject matter expert should be arranged for delivering lecture on the safe operation of Electric over head Crane and tackles. The codes of hand signals recommended for operation of Electric over head areas should be used. Crane Operator must take signals from the person responsible for the lift and must make no movement until such a signal is given. Only signals in accordance with the relevant codes should be used. Over loads are forbidden except for the purpose of test and the operator should demand a weight check on any suspected load. The slinger is responsible for ensuring that the load is properly sling before giving instructions to the driver. Under no circumstances must any person be allowed to ride on the load or on the empty hook.

IDENTIFICATION OF GAS CYLINDERS The prerequisite of safely using cylinders is the knowledge of distinguishing gas cylinder. There are different colours and different characters painted on the surface of gas cylinders to identify the different kinds of medium filled in gas cylinders: Medium

Surface Colour

Character

Colour Of Property Characte r

Hydroge n

Dark Green

Hydrogen

Red

Highly combustible

Oxygen

Azure

Oxygen

Black

Highly combustible

Ammoni a

Yellow

Liquid Ammonia

Black

Poisonous, combustible

Chlorine

Gas Green

Liquid Chlorine

White

Toxic

Nitrogen

Black

Nitrogen

Yellow

Inert

Acetylen e

White

Acetylene

Red

Combustible

COMPRESSED GAS CYLINDERS SAFETY Store, handle and transport with care.

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Industrial Safety

Look for signs of danger; including leaks, corrosion, cracks or burn marks, contaminated valves, worn hoses, broken gauges or regulators. Identify the gas in the cylinder before using it. Keep steel cap on while stored. Keep upright and secured with a safety chain. Make sure connections and regulators are in good condition. Point outlets away from people or sources of ignition when opening cylinder. Mark empty cylinders ―MT‖ or ―Empty.‖ Store empty cylinders separate from full cylinders. Store oxygen and fuel gas cylinders separately. Rotate cylinder storage so that older stock is used first. Store oxygen at least 20 feet from flammables and combustibles, or separate them by a five-foot fire-re-sistant barrier.

HAZARDS OF ENTRY INTO CONFINED SPACES Vessels, tanks, pits etc. which contains inflammable liquid or chemical or there exist oxygen deficiency are confined spaces. No body shall be allowed to enter a tank, a vessel, a tunnel etc. containing toxic vapors or oxygen deficiency unless the atmosphere is tested and certified fit for working, after the vessel or tank is cleaned, washed and purged. Adequate ventilation and protective measures should be adopted during work inside such areas. No tank or vessel which contains or has ever contained any explosive or inflammable shall be subject to: Any welding, brazing or soldering operations Any gas Cutting or grinder cutting Any operation involving heat unless and until Standard procedure for hot work on enclosed tanks, and vessels is followed and isolating of tank / vessels is provided. If vessels and tanks above ground are made to under go hot work, the following steps are necessary for isolation Pump out inflammables

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Industrial Safety

Remove ignition smoke Blanking of inlet and out let lines by using bolted blanks Open man-holes Remove sludge Monitor wind direction Perform gas flammability test Isolation of moving part like cutters and stirrers by locking isolation switches in the off-position. Pasting of notice ―Danger, men working in tank‖ out side the tank. Cleaning of tanks and vessels Before starting of hot work, vessel or tanks shall be completely cleaned by taking the following steps. Washing with cold water with high pressure hose Air blowing for removal of volatile liquid Steaming out Where sludge is present, filling with water and agitation with paddles, compressed air or a perforated steam pipe is usually effective. Washing with hot detergent solution

VENTILATION

OF VESSELS AND TANKS

Adequate ventilation of vessel or tank shall be provided for purging the atmosphere before entry and should be continued through out during work and before re-entry for further work. Ventilation should be provided to sweep out traces of dangerous fumes or to clear out an atmosphere which may be deficient in oxygen. A tank or vessel with bottom out let shall easily be ventilated A tank with out bottom out lets air shall be piped from a fan or compressor to the bottom of the tank. If a inert gas has been used to purge the tank or vessel, this gas should be replaced with a breathable atmosphere. One useful method is to refill the tank with water, emptying it when the inert gas has dispersed. Use of internal combustion engine should always be avoided in vessel and tank as it rapidly uses air in a tank and produce oxygen deficiency and also draws fumes from out side the tank as a result of induced drought.

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Industrial Safety

TESTING

OF TANK OR VESSEL FOR HAZARDOUS FUMES AND OXYGEN DEFICIENCY .

Testing for dangerous gases, explosive hazards and lack of oxygen is necessary. Standard procedure shall be used for testing of confined spaces for oxygen deficiency, hazards fumes and explosive hazard. Proper respiratory protection i.e. breathing apparatus shall be used if there exist oxygen deficiency and hazardous fumes. Entry into confined space is not allowed without respiratory protection until the atmosphere is tested and certified safe.

ELECTRICAL SAFETY RULES There are ways to work with or near electrical equipment and wiring that will help keep you safe. All workers should follow these rules, whether or not they are electricians. Clothing: Do not wear rings, watches, or any metal jewelry or ornaments when you are working near electrical circuits. Do not wear a metal hard-hat. Wear shoes with non conducting (rubber) soles. Equipment: Do not use metal ladders or un-insulated metal tools near electricity. Use only intrinsically safe or explosion-proof tools and hand lamps. In dangerous location like metal tanks, use 6 or 12 volts equipment. Keep electrical machinery free of dust, dirt, and oil. Do not store lunch or anything else in switch boxes. Keep all switch doors closed. Be sure all equipment meets the requirement of a recognized testing laboratory. Never overload a circuit, event when all equipment is certified. Examine all electrical tools and equipment for signs of damage. Never use faulty power tools. When tools or their cords are damaged, replace them at once. Wiring: Wires with damaged or deteriorating insulation should be replaced. Only in an emergency, and for temporary use only, should a wire be wrapped with electrical tape. When joining wires, tape the connection, cap the wires with wire nuts, or coat them with a special potting compound. These methods prevent accidental contact with a bare wire. Water: Water and electricity do not mix. Check your work area for puddles and wet surfaces. Never try to put out an electrical fire with water. Use the extinguisher designed for electrical fires. Making Repairs: The most important rule to follow when making repairs on or near an electrical circuit is to shut off and lock out the power. Then, to be sure, test the circuit with a current tester or meter before you work on it. Obey the lockout rules in your plant.

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Industrial Safety

FIRE Jobs that involve welding, flame cutting and grinding may cause fire. Before start of work, carry out inspection of area and remove any combustible materials from the area. Nearby equipment and hole / opening in floor shall be covered by fire blankets. Appropriate fire extinguishers and water buckets shall be placed near the job site. A fire fighter will supervise the activity. The area will be watched for one hour after the activity is finished.

HAZARDS OF FALLS Falls to a lower level This type of fall can arise in several ways, the most common of which are: Falls through floor openings and into pits, vessels and trenches Falls from roofs Falls from ladders and stains Falls from high working places.

PRECAUTIONS All openings in floors including doors through which a person could fall onto a lower floor or into pit or vessel shall be properly guarded with fix barrier rails of adequate height, which shall be firmly supported and strong enough to with stand rough usage and occasional impacts. Safety belts shall be used while working at heights.

HAZARDS

OF

FALLING

OBJECTS

Protection against injury from falling object shall be ensured by taking following measures. Never work under suspended loads of cranes. Never through any object from height Tool box managing on hook shall be used instead of loose tools Care shall be taken in stacking materials.

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Industrial Safety

Safety net shall be fixed below the work area so that accidentally falling objects shall be trapped in the net. Area on ground beneath the working area shall be cordoned and supervised by safety / security personal Worker shall wear protective clothing, safety helmet, safety shoe, and safety gloves.

HAZARDS OF COMPRESSED AIR Most workshops and factories are equipped with a comprehensive system of compressed air connections for general use. It is not always appreciated that compressed air, at the normal factory pressure of 5—6 bar, can cause grievous injury to workers, whether they are actually operating the compressed air equipment, or merely standing within a range of up to 12 m from it. General cleaning down of machines and work surfaces, or cooling of parts, are among the common usages of compressed air in factories. When ‗blowing down‘, the danger lies in particles of metal and swarf which, propelled at high velocity, can get into the operator‘s eyes—when cleaning out a blind hole, for example. Or, and this is common, the particles can be blown into the eyes of a person standing nearby, whose reflexes are not conditioned to the danger. There is danger in allowing compressed air to enter the blood stream through a cut or abrasion on the skin. This has been known to happen, with fatal results, when a workman was using compressed air equipment to clean his clothes after work: a highly dangerous practice which must be strongly discouraged. Apprentices and young factory workers not made aware of the dangers, can injure themselves severely, and injure other people, if they are allowed to indulge in ‗horseplay‘ while using compressed air equipment. They must be well and fully trained in the correct use of all such equipment. There is a high and sometimes dangerous noise level from compressed air jets. This noise may occur during a cooling or drying-off operation; generated over a long period it can cause damage to hearing. Harm can also be done to machinery. When cuttings are being blown from a surface, for example, they may become lodged in gearing or under slides and, if they remain unnoticed, can cause damage. It should always be remembered that compressed air is dangerous, compressed air is expensive, and compressed air is not a toy. Operators must be trained to recognize the dangers en that they may work in personal safety and not endanger by-standers or machinery. Taking precautions to reduce the accident

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Industrial Safety

risk and costs (the direct cost of the compressed air and the indirect cost of industrial injuries) is a common sense, managerial responsibility. HAZARDS OF WELDING A weld is defined as a local coalescence of metal, wherein coalescence is produced by heating to suitable temperature, with or without the application of pressure, and with or without the use of filler metal. The filler metal may have a melting point the same as the base metals as in Air or Gas welding or it may have a lower melting point but above 427 OC (800 OF). This definition includes brazing, but excludes soldering.

THERMAL CUTTING Thermal cutting process or removal metal by local melting or by the reaction of the metal with oxygen, sometimes with fluxes at an elevated temperatures or by a combination of both.

METHOD

OF

WELDING /CUTTING

Gas welding and cutting Arc welding and cutting Resistance welding Electron beam welding Friction welding Ultrasonic welding Explosive welding Laser beam welding

WELDING/CUTTING HAZARDS (COMMON) Light Rays Arc/gas welding produce Infra red and ultra violet radiations which are harmful to eyes and skin. Following protection shall be used.

Area

Protection

Eye

Tinted goggles/shield Partition walls

Skin

Dark Clothing Thick woolen clothing

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Industrial Safety

Avoid nylon clothes Use Special skin creams Isolation of nearby chlorinated solvents is must, which may get vaporized and catch fire Welding or hot slag may cause fire Precautions Combustible material must be removed from welding area or covered with fiber glass or steel sheets. Wooden platform must be covered with steel sheets Cracks/holes in floor must be covered.

WELDING

FUMES AND TOXIC HAZARDS

Normally these causes flue temperature, aches and respiratory problems Precautions Proper fume hood and exhaust arrangement must be provided.

ARC

WELDING /CUTTING HAZARDS

Electric shock Although the open circuit voltage is not high (15-40 volts, current 500 A DC/AC) but even then a hazard should not be overlooked. Worn out and loose cables may cause an accident. Precaution Care must be taken of worn-out cables Welder shall get himself insulated.

HAZARDS

OF GAS SHIELDING

Normally argon, helium or CO2 (Carbon Dioxide) gases are used for shielding which are supplied in cylinders. Argon and CO2 are heavier then air and will easily displace air and cause oxygen deficiency in pits vessel and excavations. Precaution The atmosphere must be well ventilated during the welding / cutting process.

GAS

WELDING AND CUTTING HAZARDS

Gas welding involves use of oxygen and acetylene gas cylinders, hoses, reducers, torches and intense flames.

PRECAUTION Cigarette buts or any gloving article can burst into flames in presence of oxygen Acetylene itself is explosive and cannot be handled safely above 15 PSI.

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Industrial Safety

GAS

CYLINDERS HAZARDS AND PRECAUTIONS

The handling of compressed and liquefied gas in cylinder present hazards Precautions Cylinders shall be used in up-right position Cylinders shall not be taken inside tanks/vessels Empty cylinder shall be handled with same care as filled cylinders. Cylinder valve shall be opened slowly. Cylinder shall not be used without guage. Leaked cylinders shall be removed to a safe place and shall be labeled. Shall take care not to allow a spark near cylinder Various gas cylinders shall not be mixed Cylinder shall not be filled without pressure testing

HAZARDS

OF WELDING TORCHES AND PREVENTIVE MEASURES

Torches made by reputed manufacturer shall only be used. Welding head, tip or nozzle suitable for the job shall only be used. Weld heads tip or nozzle shall be screwed in properly. Gas supply shall be first shut-off before disconnecting a torch from the hose. Pilot light or spark shall be used for lightening of a torch and torch shall be pointed to a safe direction. Torch shall never be put down without tuning the gas-off. Welding hose shall be protected against sharp edges of metals.

PERSONNEL PROTECTIVE EQUIPMENT DEFINITION To protect against unavoidable work Hazards, special clothing and Devices are used. These are called Personnel Protective Equipment (P.P.E).

PURPOSE To protect workers from the risk of injury by providing a safety barrier against work place hazards or provide barrier between the person at risk and the potential instrument of injury.

SCOPE Protective Equipment cannot prevent accidents

22

Industrial Safety

It can prevent and minimize injuries to the workers when accident happens. Potential instrument of injury: Sharp, abrasive, corrosive, heavy, hot, irritant or harmful objects.

23

Industrial Safety

PROTECTION

REQUIRED AT WORK PLACES :

Head Protection. Hearing Protection Eye and Face protection. Respiratory Protection. Hand protection. Foot protection. Fall/Falling object protection.

HEAD

PROTECTION

(SAFETY HELMET )

Head is the most precious/vital part of the body. It is inherently safe but requires more care and protection.

SAFETY HELMET To provide adequate head protection, safety helmet have an adjustable head band and suspension webbing. These safety helmets can withstand heavy impact without denting or breaking and resist penetration of falling objects. Safety helmet is meant mainly for head protection from falling objects but it is also required to protect against heat, chemical splashes and protect wear’s hair from contact with machinery part. Such area/places are defined through signs and posters.

HEARING PROTECTION The risk due to noise hazard can be defined as Excessive exposure to noise causes injury to hearing. Continued exposure to sound levels in excess of 90 dB causes partial or complete loss of hearing i.e. deafness. Hazard limit is 90 dB (A) (as the upper limit for habitual exposure to noise). Measurement: dB (A) is the unit used for measurement of sound energies which could cause occupational deafness. Sound level meter gives a measure of the rate of flow of acoustical energy. The “A” weighting refers to a filter which removes a proportion of low frequencies and also certain high frequencies. The table given below describe the exposure time versus sound level limit in dB (A).

Time limit (Exposure time)

Limit dB(A)

08 hours

90

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Industrial Safety

04 hours

93

02 hours

96

01 hour

99

30 minuets

102

15 minuets

105

Over 90 dB (A) with every increase of 3 dB (A) the safe exposure time reduces by half. Environmental Chart Sound level in (dB(A)

Examples sources.

of

Industrial

120-150

Air fields-Jet Engine

120

Threshold of pain

110-120

Pneumatic drills

100-110

Diesel locomotives

90-100

Workshops

85-100

Power Equipment

85

Acceptable noise level limit

75-95

Average factory noise

60

Normal conversation

Noise

The purpose for hearing protection is to reduce the noise emission level to the wearer. Reduction in Noise emission level by hearing protectors determines the protection which they afford against noise. The protection afforded by the hearing protectors depends upon two factors. Attenuation (noise reducing effects) The percentage of time during which hearing protectors is worn. Percentage of time worn is the first and most important element for hearing protection. It is compulsory for every worker to wear Ear plug /Ear muffs in these areas during the whole exposure time. It is the responsibility of every one to keep his ear plug and Ear muffs in a sanitary condition.

25

Industrial Safety

EYES

AND FACE

PROTECTION

The importance of eye safety is highlighted by the vulnerability of the eye. Although to counter act this, nature has provided the eye with a number of built in protective devices. The bone structure acts as a shield against large objects. The muscles around the eye act as a shock absorbers against blows. Eye brows prevent moisture running directly into eyes. Eye lids and lashes act like safety curtains, closing rapidly with a reflex action to trap small particles or insects or to shut out sudden glaring light. An extra long nerve allows for some displacement without permanent damage. And, after all this, if same thing should penetrate the defenses, the tear-ducts do their best to wash away the offending foreign body. All these natural defenses, although efficient enough for natural out-door surrounding, are inadequate in man made environment where chemicals, sharp, radiation and fast flying particles are common hazards. Eye injuries generally can be classified as: Burn

Thermal and chemicals

Laceration

Caused by any sharp piece of metal etc

Contusions Results from heavy blow may cause displacement of the lens or retina or rupture the eye ball. Burns to eyes are caused by chemicals splash and powerful infra-red or Ionizing radiation from welding operation: In case of chemical splash immediately wash eyes with plain water continuously for 15 minutes because if any delay occurs it will sock in the tissues and the process cannot be stopped easily which could damage the eye severely.

HAND PROTECTION Use of appropriate/suitable gloves is necessary when there exist hazard to protect against contact with following hazards: Sharp Abrasive Corrosive Hot and irritant substances or particles. So, suitable gloves should be used, when performing jobs such as welding, flame cutting, handling hazardous chemicals, handling Hot and cold objects or danger of cut, burns, laceration, abrasion and puncture persists. Similarly Insulation gloves should be used when working on energized electrical conductors or equipment. The usual types of gloves used for the protection of Hands from various job hazards are given below: Cotton gloves  simple gloves used for general work.

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Industrial Safety

PVC doted gloves  to protect Hand, from cut, puncture, abrasion, splinter etc PVC chemical splash gloves to avoid contact with hand/skin to prevent irritation and burn. Ordinary Rubber gloves to avoid contact with liquids, oils, lubricants etc Electrically insulated Rubber gloves use for work on energized electrical conductors or equipment. Leather gloves Use for handling hot surfaces/objects.

FOOT PROTECTION More than 10% of all disabling injuries to Industrial workers involve feet and toes. Such injuries can be reduced or even eliminated by wearing safety shoes. Steel toe cap protect the toe against falling object and striking against sharp/projected edges. The sole is anti-slip, chemical resistant, oil resistant and electrically insulated. Rubber boats or PVC over shoes must be used when handling chemicals.

BODY PROTECTION Protective clothing is used to protect against dirt, chemicals, oils, heat or contact with general articles which could cause physical damages. Dungarees are used for general purpose. Chemical resistant suits along with rubber gloves and face shield are used for handling/maintenance of equipment involving chemicals.

RESPIRATORY PROTECTION Respiratory Protection for workers against Toxic and Hazardous suspended particles or gases present in the ambient atmosphere is required when a worker is exposed or may be exposed to harmful concentration of contaminated air or when a deficiency of Oxygen exist or might exist.

TYPES

OF

RESPIRATORY

HAZARD

Dust Fumes Organic or inorganic gases/vapors Air born radioactive contamination Smoke Lack of Oxygen

FILTER

CARTRIDGES AND

C ANISTER/

FILER RESPIRATORS

A fitter respirator is a respiratory protection device dependent on ambient atmosphere where the respirator covers nose and mouth which when inhaling occurs, filters the ambient atmosphere (Air) in order to clear it sufficiently from

27

Industrial Safety

unwanted particles to prevent restriction of the normal functioning of the respiratory organs and sickness or death through inhaling of polluted air and the exhaled air is returned to the atmosphere through a non-return v/v. the device consists of:

Face piece and One or several filters

PRECAUTION

IN USE OF

FILTERS

Filter respirators cannot overcome lack of oxygen These shall not be used where ambient atmosphere contains less than 17% oxygen. These cannot be used in containers and in narrow space / rooms These cannot be used in unknown or in such ambient air conditions where the composure of the ambient atmosphere could change for the worse.

TYPE

OF

FILTERS

Gas filters Particle filters Combined filters

CLASSIFICATION

OF

FILTER

TYPES

(GAS

FILTER )

Gas filter type A Colour: brown Main area of use: Organic gases and vapors Gas Filter Type B Colour: Gray Main area of use: in organic gases and vapours (chlorine, Nitric Acid, Hydrochloric Acid, Sulphuric Acid, Soidum Hydroxide and Potasium Chromoate, Hydrogen sulphide, hydrocyamic acid etc.) Gas Filter Type E Colour: Yellow Main area of use: Sulphur dioxide and hydrogen chloride Gas Filter Type K

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Industrial Safety

Colour: Green Main area of use: Ammonia

SPECIALIZED GAS FILTER CO (Carbon Monooxide) Type Filter Colour: Black Main area of use: carbon monoxide during fire fighting HG (Mercury) Type Filter Colour: Red Main area of use: Mercury – vapors NO (Nitrogen Monooxide) Type Filter Colour : Blue Main area of use: Nitro gases, also nitrogen monoxide Reactor Type Filter Colour: Orange Main area of use: Radioactive iodine including radioactive iodine methane

STORAGE

OF

GAS FILTERS

Gas filter when unused (factory packed) and sealed and stored in rooms of normal humidity, temperature and air compound usually have a storage ability of Type A Types B and CO Types E and K

5 years 4 years 3 years

Filters that are no longer factory sealed must be used within 6 months. Gas filters must be changed as soon as smell or taste occurs. A much shorter period of use is to be expected with gas filters that have been used repeatedly or stored opened.

PARTICLE FILTERS (PARTICULATE MATTER FILTER ) A particle filter is a part of a filter respirator which filters the ambient atmosphere and frees it from unwanted particulate matter to such an extent that a malfunctioning of the respiratory organs, as well as sickness and death through inhaling contaminated air are prevented.

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Industrial Safety

CLASSIFICATION

OF

PARTICLE FILTER

Particle filters are distinguished by the letter ―P‖ P1 Class

Low concentration, solid particulates matters (inert bodies)

P2 Class Medium concentration, solid and liquid particulates matter (slightly poisonous bodies) P3 Class High concentration, solid and liquid particulates matter (highly poisonous bodies)

COMBINED FILTERS A combined filter filters harmful gases and vapors (danger gases) as well as particulates matter out of the ambient atmosphere.

INDEPENDENT HOSE PIPE LINE, SELF CONTAINED An apparatus operating independently of the ambient atmosphere, supplies the user with breathable air from an external breathing source. Self-contained compressed air apparatus are ―Open-circuit Breathing Apparatus‖ supply breathable air through breathing apparatus containers / air cylinders and are used independent of the area of use. Closed-circuit breathing apparatus are Oxygen breathing apparatus which are used independently of the area of use. Compressed-air breathing apparatus and oxygen breathing apparatus differ in principle of structure and period of use.

SELF-CONTAINED

OPEN -CIRCUIT BREATHING APPARATUS

The air necessary for breathing is conveyed in one or more compressed air cylinders. The filling pressure of the cylinders is usually 200 or 300 bar The self-contained open-circuit compressed air breathing apparatus use a pressure gauge for controlling the pressure of the air volume. Audible warning devices are used which indicates the diminishing of the breathing air capacity Through the demand valve (lung-governed demand valve) breathable air is supplied to the user according to his needs. Full face mask is used with compressed air breathing apparatus

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Industrial Safety

FIRST AID HINTS BROKEN NECK OR BACK If the victim cannot move his fingers or if there is tingling or numbness around his shoulders, his neck may be broken. If he can move his fingers but not his feet or toes, or if he can‘t move his back or neck, his back may be broken. First aid Loosen clothing around victim‘s neck and waist. Cover him and summon a doctor or ambulance. Don‘t move him or let him try to move. Don‘t lift his head to give him water.

CHEMICAL BURNS First aid Flush the burned area with water for at least five minutes to dilute any chemical. If an eye is burned by a chemical, especially by an acid, flush gently but thoroughly with water and call the doctor.

CARBON MONOXIDE POISONING It is a colorless and odourless gas that kills without warning. Its symptoms are: Headache, dizziness, weakness, laboured breathing, possible vomiting followed by unconsciousness. Skin, fingernails may be cherry red. First Aid Get the victim into open air, or open all windows or doors, cover him with blankets to give him warmth. Begin artificial respiration.

FAINTING First Aid APlace the patient on his back, with his head low. Make sure that his airway is clear and he is breathing properly. Loosen tight clothing, apply cold cloths to his face. If the fainting lasts for more than two minutes, cover him and call ambulance. BSeat a person who feels faint. Fan face or sponge with cool water. Lower head to knees to encourage blood flow. If he faints, lay him down, turn head to the side, and wave smelling, salts or spirits of ammonia under the nose. If the faint lasts more than a few minutes, call a doctor; if person regains consciousness, keep him quite and lying down for 15 minutes.

ELECTRIC SOCK

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Industrial Safety

The fist and foremost thing to do is to switch off the electricity from the main system. If this is not possible then do the following: Remove the contact of victim‘s body from source of electric current, using a tree branch, a dry rope or dry clothing. Do not touch the victim until contact with current has been broken. Check to see if victim is breathing and has a pulse. If necessary apply mouth to mouth breathing and send for medical aid at once.

FIRST AID

FOR

SHOCK VICTIMS

The most important things to know about first aid for shock victims are: Never touch a victim of shock who is still in contact with the source of electricity. Act swiftly. Send for medical assistance If you touch someone who is still in contact with the electrical source, you will also become part of the circuit. Then there will be two victims instead of one. If the person is frozen to the energized conductor, the first thing to do is shut off the electricity. If control is very far away, drag or push the victim away from the electricity with a piece of nonconductive material. Make sure the material you use is dry. If live wires are lying on or near the victim, use a nonconductive material to move them away. Start first aid as soon as it is safe to do so. If the heart has stopped breathing, start heart massage and mouth-to-mouth resuscitation immediately. If you do not act within four minutes, the victim will suffer permanent brain damage. If the heart is beating, lay the victim flat and raise the leg by placing something under them. Keep the victim warm. Do not give fluids if the victim is unconscious or nauseous. If the victim is burned, cut away loose clothing and immerse the burned area in cold water or cover with cold, wet compresses.

APPENDIX PAIN Symptoms Nausea, vomiting, severe pain in the stomach, fever, the right side of the abdomen becomes hard, tense and is sore or painful to touch.

FIRST AID Do not let him eat or drink anything. Do not give the patient any laxative. Take his temperature and take the patient to the Hospital at once.

BLEEDING AND WOUNDS To stop bleeding, firmly squeeze the sides of the wound together or apply pressure with the thumbs at the sides of the wound. Cleanse around and away

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Industrial Safety

from the wound, taking care not to disturb any blood clot. Apply and maintain pressure to bleeding part with dressing, cover with pad and bandage firmly. If bleeding is not controlled, apply more pads and increase pressure with the hand or additional bandages. Immobilize the injured part and treat for shock.

SHOCKS Symptoms are pale; cold skin; rapid pulse; shallow breathing; weakness; Sock itself can be fatal, Reassure the casualty and lay him down at absolute rest. Loosen any tight clothing, Wrap in blanket or coat but DO NOT OVERHEAT, apply artificial heat, or rub. Get casualty to hospital as soon as possible.

BURNS OR SCALDS To alleviate pain, immerse part in Ice water if possible. DO NOT remove burned clothing break blisters or apply ointments or oils. Cover burned area with dry quaze or some clean fabric and attach with bandages. If burn is sever, treat for shock and take patient to hospital without delay.

BROKEN BONES Fractures should be moved as little as possible. Immobilize and support the injured part at once. Upper limbs may be gently secured to the body in the most comfortable position. When a leg is fractured leave casualty lying in a position as comfortable as possible and call a doctor or ambulance. If transport is essential the injured limb may be secured to the sound one.

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Industrial Safety

POISON If patient is unconscious do not attempt to treat except with artificial respiration, if needed. Conscious casualties of corrosive poison (which destroy tissue, e.g. acids should be given large quantities of milk to drink. With narcotics (e.g. sleeping pills) the casualty should be made to vomit by touching the back of his throat or given him two tablespoons of salt in a glass of warm water to drink.

FROSTBITE Warm frozen part in water (102-105 F). Do not use heat lamp or hot water bottle. Do not rub.

SUNSTROKE Sponge body with cool water or rub with alcohol.

HEAT EXCHAUSION Give victim slips of salt water (1 teaspoon of salt per glass ½ glass every 15 minutes for one hour). Loosen clothing and apply cool wet cloth. Keep lying down with feet elevated. Take to the hospital.

INSECT BITES AND STINGS Attempts to remove stinger. Cover area with paste of baking soda; calamine lotion ma be helpful later to reduce itching. If victim faints, collapses, or if body swells call physician immediately.

EXHALED AIR RESUSCITATION The ―exhaled air‖ (mouth to mouth, or mouth to nose) method of artificial respiration is strongly recommended and should be learned by everyone. Lay patient on his back. Tilt the head and chin away from the chest to clear airway, making sure that it is not obstructed by the tongue or foreign matter. Open your mouth and take a deep breath. Pinch the casualty‘s nostrils together, then seal your lips around mouth. Blow into his lungs until the chest rises, then remove your mouth and watch the chest deflate. Repeat, giving the first four inflation as rapidly as possible. Lung inflation can be carried out through the nose. The casualty‘s mouth should be sealed with the thumb holding the lower jaw.

HEART ATTACKS The American Heart Association says that these are the usual warnings of heart attack, although symptoms vary. Prolonged, oppressive pain or unusual discomfort in the center of the chest, behind the breast bone pain may radiate to shoulder, arm, neck or jaw. The pain or discomfort is often accompanied by seating, nauseas, vomiting and shortness of breath may also occur. Sometime these symptoms subside and then return.

34

Industrial Safety

Minutes count when heart attack strikes Act promptly. Call a doctor and carefully describe the symptoms. If no doctor is immediately available, get the victim to a hospital emergency at once.

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Industrial Safety (Electrical Safety)

INDUSTRIAL SAFETY (ELECTRICAL SAFETY) INTRODUCTION Approximately 1100 deaths, resulting from electrical shock at home or on the job, are reported each year in the United States. During our daily routine, we are probably exposed to many voltages that could be deadly. Modern life depends on electricity to run machinery, to provide heat and light, and to do many of the jobs everyone takes for granted. Handled with care and respect, electricity is safe and useful. But when it is handled with ignorance or disregard for safety, electricity can be a real killer. Ignorance of safety regulations is no excuse for violating them. In fact, anyone can be fired for doing so. If there is any doubt about the meaning of a rule, ask your supervisor to explain it to you. Every worker should report any defective condition or near accident promptly.

ELECTRIC SHOCK The primary variable for determining the severity of electric shock is the electric current which passes through the body. This current is of course dependent upon the voltage and the resistance of the path it follows through the body. One instructive example of the nature of voltage is the fact that a bird can sit on a high voltage wire without harm, since both of its feet are at the same voltage. You can also see that the bird is not grounded--you will not be shocked by touching a high voltage if there is no path for the current to reach the Earth or a different voltage point. Typically if you touch a 120 volt circuit with one hand, you can escape serious shock if you have insulating shoes which prevent a low-resistance path to the ground. This fact has led to the common ―hand-in-the-pocket " practice for engineers and electrical workers. if you keep one hand in your pocket when touching a circuit which might provide a shock, you are less likely to have the kind of path to ground which will result in serious shock.

CURRENT

INVOLVED IN ELECTRIC SHOCK

The electric current in amperes is the most important physiological variable which determines the severity of an electric shock. However, this current is in turn determined by the driving voltage and the resistance of the path which the current follows through the body. The amount of the current depends on the potential difference and on the resistance.

36

Industrial Safety (Electrical Safety)

The effects of low current on the human body range from a temporary mild tingling sensation to death. An electric shock can injure you in either or both of the following ways. A severe shock can stop the heart or the breathing muscles, or both. The heating effects of the current can cause severe burns, especially at points where the electricity enters and leaves the body. Other effects include severe bleeding, breathing difficulty, and ventricular fibrillation (a condition where the heart does not stop, but contracts irregularly). High potential difference itself never killed anyone. However, it can startle you, causing you to lose your balance and fall. This is especially dangerous if you are standing on a ladder or scaffold. It is the current that does the damage to the human body. Current depends on the potential difference across a circuit, and on the circuit‘s resistance. The resistance of the human body equals the internal resistance of the body, plus the resistance of the skin and the point of contact. One difficulty in establishing the conditions for electric safety is that a voltage which produces only a mild tingling sensation under one circumstance can be a lethal shock hazard under other conditions. Will 120 V produce a dangerous shock? It depends! If your body resistance is 100,000 ohms, then the current which would flow would be: I = 120 volts / 100,000 ohms = 0.0012 A = 1.2 mA. This is just about at the threshold of perception, so would only produce a tingling sensation. But if you are sweaty and barefoot, then your resistance to ground may be as low as 1000 ohms. then the current would be: I = 120 volts / 1000 ohms = 0.12 A = 120 mA. This is a lethal shock, capable of producing ventricular fibrillation and death.

37

Industrial Safety (Electrical Safety)

PHYSIOLOGICAL EFFECTS

OF

ELECTRIC SHOCK

Electric Current ( 1 second contact Physiological Effect )

Voltage required to produce the current with assumed body resistance: 100,000 ohms

1,000 ohms

1 mA

Threshold of feeling, 100 V tingling sensation.

1V

5 mA

Accepted as maximum 500 V harmless current.

5V

10 – 20 mA

Beginning of sustained muscular contraction 1000 V ( Cannot let go current )

10 V

100 – 300 mA

Ventricular fibrillation, fatal if continued. 10,000 V Respiratory function continues.

100 V

6A

Sustained ventricular contraction followed by normal heart rhythm (defibrillation). 600,000 V Temporary respiratory paralysis and possibly burns.

6000 V

BIOLOGICAL EFFECTS

OF

ELECTRIC SHOCK

The effects produced by an electric shock are a function of the duration, quantity, frequency and path of the current passing through the body, as well as skin moisture. Your nervous system is an electrical network that uses extremely low currents. An electric shock--with even very low current--can disrupt normal functioning of muscles--most significantly, your heart. Electricity also produces violent muscle contractions which is why a person receiving a shock is frequently unable to "let go". It also may cause the heart to lose its coordination or rhythm. These effects can be caused by currents that produce no noticeable heating of tissue or visible injury.

38

Industrial Safety (Electrical Safety)

Electric shock can also produce rapid and destructive heating of body tissue. Seemingly minor external effects (specifically burns) may be indicative of much more extensive internal injury. There are other, potentially delayed effects.

BASIC SAFEGUARDS One of the best ways to prevent electrical accidents at industrial sites is to be aware of electrical dangers in the workplace. Once hazards have been identified, they must be pointed out and proper steps taken by a qualified person. The following, where used, will improve the safety of the workplace: i.

Maintain good housekeeping and cleanliness.

ii.

Identify and diminish potential hazards.

iii.

Anticipate problems.

iv.

Resist pressure to ―hurry up.‖

v.

Plan and analyze for safety in each step of a project.

vi.

Document work.

vii.

Use properly rated test equipment and verify its condition and operation before and after use.

viii.

Know and practice applicable emergency procedures.

ix.

Become qualified in cardiopulmonary resuscitation (CPR) and first aid and maintain current certifications.

x.

Wear appropriate personal protective equipment (PPE).

xi.

Refer to system drawings and perform system walkdowns.

xii. Electrical equipment should manufactures instructions.

be

maintained

in

accordance

with

the

xiii.

While working near electrical circuit do not wear, rings, watches, metal jewelry, metallic hard hats etc. Wear rubber sole shoes / rubber insulated gloves.

xiv.

Double insulated and explosion proof electrical tools should be used while working on electric circuits and equipment.

xv.

Do not hang clothes over electric panel and switchgear.

xvi.

Do not touch switches with wet hands

xvii.

Do not stand on wet floors

39

Industrial Safety (Electrical Safety)

xviii. When making repair of electrical circuits and machines main power shall be switched off and locked out. xix.

Do not touch the energize part of electrical equipment or rotating parts of machinery.

xx.

Prior the work tools and equipment shall be checked carefully.

40

Industrial Safety (Electrical Safety)

GENERAL REQUIREMENTS This section deals with the reliability and effective maintenance of electrical systems that can be achieved in part by careful planning and proper design. The training of personnel in safety-related work practices that pertain to their respective job assignments is outlined.

RESPONSIBILITIES Employees are responsible to comply with occupational safety and health regulations and standards that apply to their own actions and conduct, including immediate reporting to management of unsafe and unhealthful conditions.

REVIEWS/INSPECTIONS All modifications to existing facility and projects and new facilities should be subject to inspection by the authority having jurisdiction or their authorized designee to verify compliance with the codes and standards in effect on the date that such work was approved by a final design review. If the installation involves a hazard to life, equipment, or property, current standards and codes should be used to mitigate the hazard.

ELECTRICAL MAINTENANCE OR REPAIRS Only qualified persons shall perform electrical repairs. It is dangerous for an unqualified worker to attempt electrical repair. Before any electrical maintenance or troubleshooting is performed, sources of electrical energy shall be deenergized, except where it is necessary for troubleshooting, testing, or areas that are infeasible to deenergize. All energy sources shall be brought to a safe state. For example, capacitors shall be discharged and high capacitance elements shall be short-circuited and grounded.

WORK ON ENERGIZED/DEENERGIZED ELECTRICAL EQUIPMENT The first consideration for working on any electrical system is to have the circuit positively deenergized. All circuits and equipment must be considered energized until opened, tagged and/or locked according to an approved procedure and should be proven deenergized by testing with an approved testing device known to be in proper working order. Review system drawings and/or perform system walkdowns. Where the possibility exists that the circuit can become energized by another source or where capacitive devices (including cables) may retain or build up a charge, the circuit should be grounded and shorted. The grounding and shorting device should be selected and installed in accordance with appropriate standards. Whenever work is to be performed on a positively deenergized system, the worker must also identify and protect against any accidental contact with any exposed energized parts in the vicinity of the work.

41

Industrial Safety (Electrical Safety)

CONSIDERATIONS FOR WORKING ON ENERGIZED SYSTEMS AND EQUIPMENT Qualified employees performing such tasks as electrical repairs, modifications, and tests on energized electrical systems, parts, and equipment need to comply with the following: i.

Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations.

ii.

Work performed on energized electrical systems and equipment may be done only if a supervisor and/or cognizant safety professional and the personnel performing the work determine that it can be done safely. Approval should be given for each job. Approval for the same job performed repeatedly may be given through the use of an approved procedure or job safety analysis.

iii.

Personnel shall not work on energized circuits unless they are qualified to do so, or, for training purposes, unless they work under the direct supervision of a qualified person.

iv.

Sufficient protection in the form of insulated tools and insulated protective equipment, such as gloves, blankets, sleeves, mats, etc., shall be used while working on energized circuits.

v.

Other work, independent of voltage, that presents a significant shock or arc blast hazard to employees, needs to be evaluated as to the number of employees involved.

vi.

At least two employees shall be present while the following types of work are being performed: a.

Installation, removal, or repair of lines that are energized at more than 600 volts.

b.

Installation, removal, or repair of deenergized lines if an employee is exposed to contact with other parts energized at more than 600 volts,

c.

Installation, removal, or repair of equipment, such as transformers, capacitors, and regulators, if an employee is exposed to contact with parts energized at more than 600 volts.

d.

Work involving the use of mechanical equipment, other than insulated aerial lifts, near parts energized at more than 600 volts, and

e.

Other work that exposes an employee to electrical hazards greater than or equal to those listed above.

42

Industrial Safety (Electrical Safety)

f.

Exceptions to the items listed above are:

g.

Routine switching of circuits, if the employer can demonstrate that conditions at the site allow this work to be performed safely,

h.

Work performed with live-line tools if the employee is positioned so that he or she is neither within reach of nor otherwise exposed to contact with energized parts, and

i.

Emergency repairs to the extent necessary to safeguard the general public.

j.

Taking voltage measurements may subject personnel to exposed energized parts. Where it is determined personnel are subject to contacting exposed energized parts, personnel shall use the appropriate protective equipment for the voltage levels involved.

43

Industrial Safety (Electrical Safety)

WORKING SPACE AROUND ELECTRICAL EQUIPMENT Working space around electrical enclosures or equipment shall be adequate for conducting all anticipated maintenance and operations safely, including sufficient space to ensure safety of personnel working during emergency conditions and workers rescuing injured personnel. Spacing shall provide the dimensional clearance (discussed in the following subsections) for personnel access to equipment likely to require examination, adjustment, servicing, or maintenance while energized. Such equipment include panel boards, switches, circuit breakers, switchgear, controllers, and controls on heating and air conditioning equipment. A minimum working space must be provided in front of electrical equipment. This provides room to avoid body contact with grounded parts while working with energized components of the equipment. Space may be centered in front of the equipment or can be offset. The depth of the working space shall be clear to the floor. The depth of the working space varies, depending upon existing conditions. The conditions for working voltages below 600 Volts are as follows: Condition 1: These are exposed live components on one side of a space and ungrounded parts on the other side. Condition 2: The electrical equipment is mounted or set on one wall, and the wall on the opposite side is grounded. If the qualified worker should accidentally contact the conductive wall while touching live components, a circuit would be completed to ground and a fatal shock might occur. Condition 3: The electrical equipment is mounted or set on one wall, and additional electrical equipment is mounted or set on the opposite side of the room. There are live components on both sides of the room. The qualified worker might accidentally make contact with live components and be in series with a hot phase and the grounded metal of the electrical equipment, which could produce a fatal shock. A summary of clearance, depending on Voltage levels and above mentioned conditions is given below:

44

Industrial Safety (Electrical Safety)

Condition 1 Volts to ground

Condition 2

Condition 3

0 - 150 V

Min. dist. 3 ft.

Volts to ground Min. dist. Volts to Min. dist. ground 0 - 150 V 3 ft. 0 - 150 V 3 ft.

151 - 600 V

3 ft.

151 - 600 V

3 1/2 ft.

151 600 V

- 4 ft.

The conditions for voltages above 600 Volts are as under: Condition 1: Where there are exposed live components on one side of a space and no live or ungrounded parts on the other side. Condition 2: Where there are exposed live components on one side and grounded parts on the other such as concrete, brick, and tile walls that are considered to be grounded parts. Condition 3: Where there are exposed live components on both sides.

Condition 1 Volts to ground

Condition 2 Min. dist.

Volts to ground

Condition 3 Min. dist.

Volts to ground

Min. dist.

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Industrial Safety (Electrical Safety)

601 -

2,500 V

3 ft.

601 -

9,000 V

4 ft.

2,501 -

9,001 - 25,000 V

5 ft.

9,001 - 25,000 V 6 ft.

9,001 - 25,000 V

25,001 - 75,000 V 6 ft.

25,001 - 75,000 V 8 ft.

25,001 - 75,000 V 10 ft.

above 75,000 V

above 75,000 V

2,501 -

8 ft.

2,500 V

4 ft.

9,000 V 5 ft.

601 2,501 -

2,500 V

5 ft.

9,000 V 6 ft.

10 ft. above 75,000 V

9 ft.

12 ft.

Figure 2-4. Minimum clearances in front of electrical equipment (over 600 V).

Many electrical hazards and work practices are the same regardless of the voltage involved. However, due to the nature of high voltage work, there are many hazards and work practices that are specifically related to high voltage. Each employee who is exposed to flames or electric arcs does not wear clothing that, when exposed to flames or electric arcs, could increase the extent of injury that would be sustained by the employee. ―Note: Clothing made from the following types of fabrics, either alone or in blends, is prohibited by this paragraph, unless the employer can demonstrate that the fabric has been treated to withstand the conditions that may be encountered or that the clothing is worn in such a manner as to eliminate the hazard involved: acetate, nylon, polyester, rayon.‖ Insulating covers are used in conjunction with line hose to cover an insulator and the conductor attached to it for protection against accidental contact. Rubber insulating blankets are molded sheets of insulating rubber or synthetic elastomer, usually square or rectangular in shape, designed to cover energized electrical equipment to prevent direct accidental contact by electrical workers. SPECIAL CONSIDERATIONS DURING ELECTRICAL WORKS

46

Industrial Safety (Electrical Safety)

WORK INSTRUCTIONS Before work begins, the qualified worker should ensure that the job to be done is in compliance with instructions pertaining to the electrical work. Electrical work should be performed according to written safety procedures and approved electrical safety manuals. Electrical work should be directed by a supervisor, qualified by training and experience in the safety-related work practices that pertain to their respective job assignments and those of their employees. Workers should report any electrical hazards to their immediate supervisor. The supervisor should take all corrective actions necessary to address an employee‘s concerns. Electrical instructions should be based on a thorough analysis of the job and its hazards. If the same task is repeated, it may be performed under specific work rules that are based on such analyses.

IDENTIFICATION OF DISCONNECTION MEANS Switches in service panels, sub panels, or elsewhere shall be marked to show what loads or equipment are supplied.

DISCONNECTING MEANS All disconnecting means (switches or circuit breakers) shall be located for easy access and shall be clearly and permanently marked to show the purposes of the disconnects, unless located and arranged so that the purpose is evident. Labeling should match and be traceable to appropriate drawings. Disconnecting means shall be capable of being locked out where required. LABELLING

ENCLOSURE LABELING Printed labeling or embossed identification plates affixed to enclosures shall comply with the requirements that disconnects be ―legibly marked‖ and that the ―marking shall be of sufficient durability‖ for the environment involved

LOAD LABELING As with the disconnecting device, the load should be labeled. For example, the motor, the controller, and the disconnecting device could have the same identification number, etc. SOURCE LABELING The source supplying power to the disconnecting means and load should be labeled as well. This requirement allows the electrical worker to know the identification of the elements from the source of power through the entire circuit.

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Industrial Safety (Electrical Safety)

ELECTRICAL PERSONAL PROTECTIVE EQUIPMENT (PPE) Qualified workers are responsible for avoiding and preventing accidents while performing electrical work, repairs, or troubleshooting electrical equipment. Personnel shall wear or use personal protective equipment (PPE), and protective clothing that is appropriate for safe performance of work. See Table 2-1.

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Industrial Safety (Electrical Safety)

Table 2-1. ANSI/ASTM standards on PPE and protective clothing.

Subject Blankets Insulating

Number and Title ANSI/ASTM

D1048-1988a,

Specifications

for

Rubber

Blankets Climbing Equipment

ASTM

F887-91a,

Specifications

for

Personal

Climbing

Equipment Dielectric Strength of

ASTM F1116-88, Test Method for Determining Dielectric

Overshoes

Overshoe Footwear ASTM F1117-87, Footwear

Specification

for

Dielectric

Overshoe

Eye and Face

ANSI Z87.1-1979, Practice for Occupational and Educational

Protection

Eye and Face Protection

Gloves and Insulating

ANSI/ASTM

Sleeves

Sleeves

D1051-1987,

Specifications

for

Rubber

ANSI/ASTM Dl20-1987, Specifications for Rubber Insulating Gloves ASTM F496-96, Insulating

Specifications

for

In-Service

Care

of

Gloves and Sleeves Hand Tools Hand

ASTM F1505-94, Specifications for Insulated and Insulating

Tools

Head Protection ANSI Z89.1-1986, Protective Helmets for Industrial Workers Requirements

49

Industrial Safety (Electrical Safety)

Leather Rubber

ASTM F696-91, Specification for Leather Protectors for

Protectors

Insulating Gloves and Mittens

Line Hoses, Insulating

ANSI/ASTM

Hoods, and

Covers

Covers

ASTM D1050, Specification for Rubber Insulating Line Hoses ASTM F478-92, Specifications for InService Care of Rubber Insulating Line Hoses and Covers

Live Line Plastic

ASTM

Tools

(FRP) Rod and Tube Used in Live Line Tools

Mats

ANSI/ASTM D178-1988, Specifications for Rubber Insulating

D1049-1988,

F711-86,

Specifications

Specification

for

for

Rubber

Fiberglass-Reinforced

Matting Protective Use by

ASTM F1506-94, Textile Materials for Wearing Apparel for

Clothing Related

Electrical Workers Exposed to Momentary Electric Arc and Thermal Hazards ASTM PS-57, Test Method for Determining the Ignitibility of Clothing by the Electrical Arc Exposure Method Using a Mannequin ASTM PS-58, Test Method for Determining the Arc Thermal Performance (Value) of Textile Materials for Clothing by Electric Arc Exposure Method Using Instrumented Sensor Panels

PVC Insulating

ASTM F1742-96, Specifications for PVC Insulting Sheeting

Sheeting

CLEANING AND ELECTRICAL TESTING OF PPE Rubber-insulated PPE issued for use shall receive periodic cleaning and electrical testing in accordance with the requirements of the appropriate ANSI/ASTM standards listed in the references of this handbook. The intervals of retest for rubber goods issued for service shall not be more than 6 months for gloves and 12 months for sleeves and blankets. Gloves or sleeves that have

50

Industrial Safety (Electrical Safety)

been electrically tested but not issued for service shall not be placed into service unless they have been electrically tested within the previous twelve months.

RETESTED PPE Retested rubber-insulated PPE shall be identified to indicate the date of the latest test or date of retest in accordance with the appropriate standard. Manufacturer‘s recommendations on the type of paint or ink to be used shall be followed.

INSPECTING PPE Employees shall visually inspect rubber-insulated PPE at the beginning of each workday prior to use and after any work performed that could damage the equipment. Such inspections shall include a field air test of the gloves used. Visual inspection shall be performed on hot sticks, grounds, aerial lift equipment and booms, rope, ladders, insulated tools, etc. Equipment that does not successfully pass visual inspection shall not be used and shall be returned for repair and testing or disposal.

STOREROOM STORAGE Since heat, light, oil, and distortion are natural enemies of rubber, rubber protective equipment should be guarded from these as much as possible. Rubber equipment shall not be stored near boiler rooms, steam pipes, or radiators and should be protected from exposure to direct sunlight. Gloves should be stored in their natural shape in the leather protector. Keep sleeves flat with the inserts left in. Blankets should be stored flat, hung on pegs by the eyelet or rolled up. Line hose should be stored in its natural shape.

LIVE-LINE TOOLS A careful periodic inspection shall be made of equipment used for handling or testing energized lines or equipment. Such tools shall be examined before each use to make certain they are in good condition. Particular attention shall be given to preserving the surfaces of wooden and fiberglass tools used around electrical equipment, including ladders, pike poles, switch sticks, live-line tools, and insulating platforms. Only colorless varnish or other appropriate transparent insulating preservative shall be used. Insulated tools shall be stored in a dry location. Suitable containers or racks shall be provided to protect the tools from mechanical damage and warping. A record of the testing of live-line tools shall be maintained.

FIBERGLASS-HANDLED TOOLS Fiberglass-handled tools shall be tested by the manufacturer at 100 kV per ft of length per 29 CFR 1926.951(d) (i) and ASTM F711. The in-service test shall be 75 kV per ft. WOODEN-HANDLED TOOLS

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Industrial Safety (Electrical Safety)

Wooden-handled tools shall be tested by the manufacturer to 75 kV per ft of length per 29 CFR 1926.951(d) (ii) and ASTM F711. The in-service test shall be 50 kV per ft.

MAXIMUM USAGE VOLTAGE Maximum usage voltage phase-to-phase or phase-to-ground for insulating blankets, mats, covers, line hose, sleeves, and gloves shall be as follows: Class

Voltage

Label Color

00

500

Beige

0

1,000

Red

1

7,500

White

2

17,500

Yellow

3

26,500

Green

4

36,000

Orange

MAXIMUM USAGE VOLTAGE FOR LIVE-LINE TOOLS Maximum usage voltage per foot of length and phase-to-phase or phase-toground for live-line tools shall be as follows: Tools with wooden handles

69 kV

Tools with fiberglass handles

93 kV

WORK PRACTICES The safe maintenance or repair of any electrical apparatus requires a thorough knowledge of engineering, safety, and repair techniques, and personnel should be familiar with the particular features of the apparatus involved. Only qualified workers should do such work and these workers should refer to the manufacturer‘s testing procedures, warnings, and instructions on how to service such equipment.

TRAINING Qualified workers shall be knowledgeable and trained in safety-related work practices, safety procedures, and other requirements that pertain to their respective job assignments. Employees shall not be permitted to work in an area where they are likely to encounter an electrical hazard unless they have been trained to recognize and avoid these hazards.

LIVE PARTS Live parts that an employee may be exposed to shall be deenergized before the employee works on or near them, unless it can be demonstrated that

52

Industrial Safety (Electrical Safety)

deenergizing introduces additional or increased hazards or is infeasible because of equipment design or operational limitations. Examples of infeasibility because of equipment design or operational limitations are as follows: 

Tests



Adjustments



Troubleshooting



Interruption of life supports



Removal of lighting in an area



Deactivation of alarm systems



Shutdown of ventilation in hazardous locations



Shutdown of a process or system creating a greater hazard.

Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electrical arcs.

SAFE PROCEDURE Safe procedures for deenergizing circuits and equipment shall be determined before circuits or equipment are deenergized. The deenergization procedures shall be included in the lockout/tagout procedure for the circuit or equipment to be deenergized.

CIRCUITS AND EQUIPMENT Circuits and equipment to be worked on shall be disconnected from all electric energy sources. Control circuit devices such as push-buttons, selector switches, and interlocks shall not be used as the sole means for deenergizing circuits or equipment

STORED ELECTRICAL ENERGY Stored electrical energy that might endanger personnel shall be placed in a safe state. Capacitors shall be discharged and high-capacitance elements shall be short-circuited and grounded if the stored electrical energy could endanger personnel.

STORED NONELECTRICAL ENERGY

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Industrial Safety (Electrical Safety)

Stored non-electrical energy in devices that could reenergize electric circuit parts shall be blocked or relieved to the extent that the circuit parts could not be accidentally energized by the device. For example, such specific devices are wound springs and pneumatic-driven devices.

LOCKOUT/TAGOUT PROCEDURE Each employer shall document and implement lockout/tagout procedures to safeguard employees from injury while they are working on or near deenergized electric circuits and equipment.

VERIFICATION OF DEENERGIZED CONDITION Verification shall be made that all live circuits, parts, and other sources of electrical energy, including any mechanical energy, have been disconnected, released, or restrained. A qualified worker shall operate the equipment operating controls, perform voltage verification, inspect open switches and draw-out breakers etc. to assure the isolation of energy sources.

VOLTAGE VERIFICATION TEST A qualified worker shall use the appropriate test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed and shall verify that the circuit elements and equipment parts are deenergized. The test shall also determine if a hazardous energized condition exists as a result of induced voltage or voltage backfeed after specific parts of the circuit have been deenergized. If the circuit to be tested is over 600 V nominal, the test equipment shall be checked for proper operation immediately before and immediately after this test. This test is also recommended for systems of 600 V or less. Testing shall be performed as if the circuit is energized. The voltage verification device used shall be rated for the application. Proximity testers and solenoid-type devices should not be used to test for the absence of AC voltage.

Employers shall implement and document a lockout-tagout program with procedures to safeguard employees from injury while working on or near deenergized systems.

APPLICATION OF GROUNDS

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Industrial Safety (Electrical Safety)

Personnel protective grounds shall be applied on circuits 600 V and above or on lesser voltages where residual charges may accumulate. Personal protective grounds shall be selected and installed in accordance with appropriate standards. Consideration shall be given to step and touch potentials in the area of the temporary ground connections.

REENERGIZING EQUIPMENT The following requirements shall be met before circuits or equipment are reenergized, even temporarily.

TESTS AND VISUAL INSPECTIONS A qualified worker shall conduct tests and visual inspections to verify that all personnel are in the clear and that all tools, electrical jumpers, shorts, grounds, and other such devices have been removed so that the circuits and equipment can be safely energized.

WARNING EMPLOYEES Employees exposed to the hazards associated with reenergizing the circuit or equipment shall be warned to stay clear of circuits and equipment.

REMOVING LOCK AND TAG Each lock and tag shall be removed by applying the following: 1. Each lockout or tag out device shall be removed from each energy-isolating device by the authorized employee who applied the lockout or tag out device, or under their direct supervision, or as stated below. 2. Exception: When the authorized employee who applied the lockout or tag out device is not available to remove it, that device may be removed under the direction of his or her supervisor. Extreme care shall be taken and specific procedures shall be followed. The specific procedure shall include at least the following elements: a.

Verification by the supervisor that the authorized employee who applied the device is not at the affected facility

b.

Making all reasonable efforts to contact the authorized employee to inform him or her that the lockout or tagout device has been removed

c.

Ensuring that the authorized employee has this knowledge before he or she resumes work at the affected facility.

SAFE ENERGIZED WORK (HOT WORK) Safety-related work practices shall be used to prevent electrical shock or other electrically induced injuries when employees work on or near electrical conductors or circuit parts that are energized. Only qualified workers who are knowledgeable and have been trained to work safely on energized circuits and to

55

Industrial Safety (Electrical Safety)

use the appropriate PPE, protective clothing, insulating shielding materials, and insulated tools shall be permitted to work on energized conductors or circuit parts.

TWO WORKERS Because of exposure to energized parts, electrical work, independent of voltage, that presents a significant shock or arc blast hazard to employees, needs to be evaluated as to the number of employees involved.

SAFETY RULES Before performing any electrical work, each individual shall be familiar with the electrical safety rules. The rules should be regularly reviewed by each employee and at periodic safety meetings to ensure that each individual understands the rules. Employees shall adhere to all safety rules at all times. Prior to beginning any work at the job site, an individual should be designated as the person in charge (PIC) to be responsible for seeing that the safety rules are followed and to coordinate all the work activities. All personnel assigned to the job shall comply with the safety rules. The following are safety directions and measures that should be followed when working on energized circuits: 1.

Know before work begins the work content and the sequence in which it should be accomplished.

2.

Know the safety procedures that shall be followed while performing the work.

3.

Ensure that the tools and instruments are in good working order and have up-to-date calibration or testing as required.

4.

Know what tools are required and how to use them and what protective equipment is required to perform the job safely.

5.

Allow only qualified individuals to operate tools and equipment.

6.

Use safety signs, symbols, or accident prevention tags to warn and protect employees where electrical hazards are likely to endanger lives.

7.

Use barricades in conjunction with safety signs where it is necessary to prevent or limit employee access to work areas where they might be exposed to uninsulated energized conductors or circuit parts. Do not use metal barricades where they are likely to cause an electrical contact hazard.

8.

Use manual signaling and alerting when signs and barricades do not provide sufficient warning and protection from electrical hazards.

9.

Limit access to the work area to authorized individuals who are familiar with the work.

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Industrial Safety (Electrical Safety)

10. Ensure that the PIC notifies all individuals involved in the work of any changes in the work conditions. 11. If unsafe conditions develop during the work process, immediately report them to the person in charge or the immediate supervisor. 12. Establish emergency safety procedures to deal with electrical accidents. UNEXPECTED ELECTRICAL HAZARDS Employees should be instructed to be alert at all times when they are working near exposed energized parts where unexpected electrical hazards may exist.

ILLUMINATION Adequate illumination shall be provided before workers are allowed to enter spaces containing exposed energized parts.

SYSTEMS UNDER LOAD Electrical equipment intended to switch current shall have a rating sufficient for the current. Manual switches and disconnects, taps, terminators, and nonenclosed switches shall not be operated while under load, unless the devices are rated as load-break type and are so marked.

WORKING WITH TEST INSTRUMENTS AND EQUIPMENT Sometimes it becomes necessary to check the continuity of power circuits, control circuits, etc., by using a particular testing instrument designed for the testing involved. The voltage device used shall be rated for the application. Proximity testers and solenoid-type devices should not be used to test for the absence of AC voltage because they have a lower voltage (usually in the range of 50 to 110 volts) below which they will not detect voltage, even if it is present. Also, these testers will not detect DC voltage or detect AC voltage in a cable that is shielded. They are very useful in certain applications such as finding cables that go through a panel but do not terminate in the panel. However, it should be noted that just because a proximity tester does not detect voltage does not mean that the equipment or device is actually deenergized. The absence of voltage can only be verified with a voltmeter rated for the application. Voltmeters, both analog and digital, are designed for a number of applications from appliance troubleshooting to power system testing. The type of voltmeter used depends on where in the power system you are using the meter. The user must read and understand the manufacturers‘ instructions on the use and application of the voltmeter. When a multi-function, multi-scale meter is used, it is important for the user to select the function and scale necessary for the task

57

Industrial Safety (Electrical Safety)

being performed in order to avoid damage or destruction of the meter and injury to the employee. The following should apply when equipment on energized circuits.

working

with

test

instruments

and

QUALIFIED EMPLOYEES Only qualified workers who are knowledgeable and have been trained to work safely with test instruments and equipment on energized circuits shall be permitted to perform testing work on electrical circuits or equipment where there is danger of injury from accidental contact with energized parts or improper use of the test instruments and equipment.

VISUAL INSPECTIONS Test instruments and equipment and all associated test leads, cables, power cords, probes, and connectors shall be visually inspected for external defects or damage before being used on any shift. If there are defects or evidence of damage that might expose an employee to injury, the defective or damaged item shall not be used until required repairs and tests have been made.

RATING INSTRUMENTS AND EQUIPMENT Test instruments and equipment and their accessories shall be rated for the circuits and equipment to which they will be connected and shall be suitable for the environment in which they will be used.

CALIBRATION OF ELECTRICAL INSTRUMENTS A record should be maintained for each instrument, by serial number or equivalent method, showing dates of inspection, calibration data as received, the date when it should be recalled from the field and a recalibration check made, and any interim repairs. After a period of time, it should become obvious what frequency needs to be established for calibrating each instrument.

ELECTRICAL PREVENTIVE MAINTENANCE The term ―electrical preventive maintenance‖ (EPM) refers to a program of regular inspection and service of equipment to detect potential problems and to take proper corrective measures.

DEFINITION An EPM program is defined as the system that manages the conducting of routine inspections and tests and the servicing of electrical equipment so that impending troubles can be detected and reduced or eliminated. Where designers, installers, or constructors specify, install, and construct equipment with optional auxiliary equipment, that optional equipment should be part of the EPM program. Records of all inspections, tests, and servicing should be documented and reviewed.

58

Industrial Safety (Electrical Safety)

All electrical equipment that is appropriate for EPM should be inspected, tested, and serviced in accordance with an EPM program. Inspections, tests, and servicing shall be performed by personnel who are qualified for the work to be performed. These qualifications can be shown by appropriate documentation of work experience, on-the-job, and offsite formal training to verify understanding and retention of minimum knowledge, skills, and abilities.

MAINTENANCE Electrical equipment should be maintained in accordance with the manufacturer‘s recommendations and instructions for the local operating environment. A copy of the manufacturer‘s recommendation should be documented and on file.

INSPECTION If an EPM program does not exist, an inspection, testing, and servicing program should be developed and implemented to establish a baseline to initiate an EPM program. The inspection frequency should be as recommended by the manufacturer. An initial period of inspection (sometimes several years) provides sufficient knowledge, which when accumulated, might permit increasing or decreasing that interval based upon documented observations and experience.

ESSENTIAL ELEMENTS The EPM program should include the essential elements .This includes planning, identifying the main parts, and utilizing available support services for a program. For example: 1.

Assigning qualified personnel

2.

Surveying and analyzing equipment maintenance requirements

3.

Performing routine inspections and tests

4.

Analyzing inspection and test reports

5.

Prescribing corrective measures

6.

Performing necessary work

7.

Preparing appropriate records.

PLANNING AND DEVELOPING AN EPM PROGRAM, AND FUNDAMENTALS OF EPM The EPM program should be planned and developed to include each of the functions, requirements, and economic considerations Electrical drawings should be kept current. A system of recording changes in electrical systems and then integrating those changes into the applicable drawings should be developed and implemented.

59

Industrial Safety (Electrical Safety)

GROUND-FAULT PROTECTION The EPM program should include the essential ingredients of ―Ground- Fault Protection.‖ This includes ground fault circuit interrupters (GFCIs) and groundfault protection for equipment (GFPE). Ground-fault protective devices are intended to protect personnel and equipment. There are two distinct types, GFCI and GFPE, and it is of extreme importance to understand the difference between them.

GROUNDING This section presents general rules for the grounding and bonding of electrical installations. Qualified workers should clearly understand the concepts of grounding practices. They should also clearly understand the definition and intent of the following components of a grounding system that are explained in this chapter: 1.

Grounded conductor

2.

Grounding conductor

3.

Grounding electrode conductor

4.

Bonding jumper

5.

Grounding electrode.

CIRCUIT AND SYSTEM GROUNDING Circuit and system grounding consists of connecting the grounded conductor, the equipment grounding conductor, the grounding busbars, and all noncurrent-carrying metal parts to ground. This is accomplished by connecting a properly sized unspliced grounding electrode conductor between the grounding busbar and the grounding electrode system. There are three fundamental purposes for grounding an electrical system: 1. To limit excessive voltage from lightning, line surges, and crossovers with higher voltage lines. 2. To keep conductor enclosures and noncurrent-carrying metal enclosures and equipment at zero potential to ground. 3. To facilitate the opening of overcurrent protection devices in case of insulation failures because of faults, short circuits, etc. EQUIPMENT GROUNDING

60

Industrial Safety (Electrical Safety)

Equipment grounding systems, which consist of interconnected networks of equipment grounding conductors, are used to perform the following functions: 1.

Limit the hazard to personnel (shock voltage) from the noncurrent-carrying metal parts of equipment raceways and other conductor enclosures in case of ground faults, and

2.

Safely conduct ground-fault current at sufficient magnitude for fast operation of the circuit overcurrent protection devices.

BONDING Caution shall be taken to ensure that the main bonding jumper and equipment bonding jumper are sized and selected correctly. Bonding completes the grounding circuit so that it is continuous. If a ground fault occurs, the fault current will flow and open the overcurrent protection devices. The means of bonding shall provide the following to ensure the grounding system is intact: 1.

Provide a permanent connection,

2.

Provide a positive continuity at all times, and

3.

Provide capacity to conduct fault current.

Supply (neutral) Transform Grounded conductor carrying fault er current Service

Over current Protective Device This conductor provides the bonding of the equipment This grounding electrode provides circuit and system grounding

equipme Phase nt conduct or This equipment grounding conductor provides equipment grounding Subpa nel Equipment with ground fault

61

Industrial Safety (Electrical Safety)

Fig: Circuit and system grounding consists of earth grounding the electrical system at the supply transformer and the line side of the service equipment. Equipment grounding and bonding is accomplished by connecting all metal enclosures and raceways together with the grounding conductors.

GROUNDED OR UNGROUNDED SYSTEMS Ungrounded systems may provide greater continuity of operations in the event of a ground fault. However, the second fault will most likely be more catastrophic than a grounded system fault. Whenever ungrounded systems are used in a facility, the maintenance personnel should receive training in how to detect and troubleshoot the first ground on an ungrounded system. Electrical systems can be operated grounded or ungrounded, depending on the condition of the systems‘ use. Electrical systems are grounded to protect circuits, equipment, and conductor enclosures from dangerous voltages and personnel from electrical shock. ―Grounded‖ means that the connection to ground between the service panel and earth has been made. ungrounded electrical systems are used where the designer does not want the over current protection device o clear in the event of a ground fault. Ground detectors can be installed to sound an alarm or send a message o alert personnel that a ground fault has occurred on one of the phase conductors. Ground detectors will detect the presence of leakage current or developing fault current conditions while the system is still energized and operating. By warning of the need to take corrective action before a problem occurs, safe conditions can usually be maintained until an orderly shutdown is implemented.

PERSONNEL PROTECTIVE GROUNDS Personnel working on or close to deenergized lines or conductors in electrical equipment should be protected against shock hazard and flash burns that could occur if the circuit were inadvertently reenergized. Properly installed equipotential protective grounds can aid in lessening such hazards by providing additional protection to personnel while they service, repair, and work on such systems.

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Industrial Safety (Electrical Safety)

Figure. If the building steel, metal water pipe, concrete-encased electrode, and ground ring are available, they must be grounded and bonded to the service equipment to create the grounding electrode system.

63

Industrial Safety (Electrical Safety)

PURPOSE OF PERSONNEL PROTECTIVE GROUNDS Personnel protective grounds are applied to deenergized circuits to provide a low-impedance path to ground should the circuits become reenergized while personnel are working on or close to the circuit. In addition, the personnel protective grounds provide a means of draining off static and induced voltage from other sources while work is being performed on a circuit. (Figure 4-9 illustrates an example of a personnel protective ground.)

CRITERIA FOR PERSONNEL PROTECTIVE GROUNDS Before personnel protective grounds are selected, the following criteria shall be met for their use, size, and application. 1.

A grounding cable shall have a minimum conductance equal to #2 AWG copper.

2.

Grounding cables shall be sized large enough to carry fault current long enough for the protective devices to sense and the circuit breaker to clear the fault without damage to cable insulation.

Figure 4-9. Equipotential personnel protective grounds are used to protect electrical workers while they service, repair, or are close to circuits that can be accidentally reenergized. 3. a.

The following are factors that contribute to adequate capacity: Cross-sectional area to carry maximum current without melting

b. Low resistance to keep voltage drop across the areas in which personnel are working at a safe level during any period to prevent reenergization. The voltage drop should not exceed 100 volts for 15 cycle or 75 volts for 30 cycle clearing times.

64

Industrial Safety (Electrical Safety)

c. Verify that the grounding cable and clamp assembly is tested periodically by using the mili volt drop, micro-ohm meter, AC resistance, or DC resistance test methods. For example, if it is desired to maintain a maximum of 100 volts across a worker whose body resistance is 1000 ohms, during a fault of 1000 amperes, a personnel protective ground resistance of 10 millohms or less is required. 4. For further information on the construction of personnel protective grounds, refer to ASTM F855-90, IEEE 524A, IEEE 1048, and Section 7.5.

GROUNDING CLAMPS Grounding clamps used in personnel protective grounds are manufactured specifically for this use. The size of grounding clamps shall match the size of conductor or switchgear bus being grounded. The ground clamp also shall be rated to handle the full capacity of the available fault currents. Fault currents can typically range in magnitude up to over 200,000 A.

SCREW-TIGHTENING DEVICES Approved screw-tightening devices designed for the purpose of pressure metalto-metal contact are required for connections to an adequate system ground.

GROUNDING CABLE LENGTH Grounding cables should be no longer than is necessary, both to minimize voltage drop and to prevent violent movement under fault conditions. For example, as a general rule, grounding cables should not exceed 30 ft for a transmission line and 40 ft for substation use.

GROUNDING CABLE CONNECTION Grounding cables shall be connected between phases to the grounded structure and to the system neutral to minimize the voltage drop across the work area if the circuit should become inadvertently reenergized. Workers shall install the ground end clamp of a grounding cable first and remove it last.

CONNECTING GROUNDING CABLES IN SEQUENCE Grounding cables shall be connected to the ground bus, structure, or conductor first, then to the individual phase conductors. The first connection of the grounding cables to the circuit phase conductors shall be to the closest phase of the system and then to each succeeding phase in the order of closeness.

REMOVING PROTECTIVE GROUNDS When removing personnel protective grounds, reverse the order they were applied to the phases. The grounding cable conductors attached to the ground bus, structure, or conductors shall always be removed last.

PROTECTIVE APPAREL AND EQUIPMENT

65

Industrial Safety (Electrical Safety)

Protective apparel shall be worn when applying or removing grounds. An insulating tool (hot stick) shall be used to install and remove grounding cables Protective apparel (personnel protective equipment) should include at least the following: 1. Safety glasses and, if necessary, face shield appropriate for fault currents available. 2.

Hardhat (Class B)

3.

Appropriate electrical gloves and protectors

4.

Appropriate clothing

GROUND FAULT CITCUIT INTERRUPTERS There are 2 classes of ground-fault circuit interrupters and each class has a distinct function. A Class A ground-fault circuit interrupter trips when the current to ground has a value in the range of 4 through 6 milliamperes and is used for personnel protection. A Class A ground-fault circuit interrupter is suitable for use in branch circuits. A Class B ground-fault circuit interrupter (commonly used as ground fault protection for equipment) trips when the current to ground exceeds 20 milliamperes. A Class B GFCI is not suitable for employee protection. Ground-fault circuit protection can be used in any location, circuit, or occupancy to provide additional protection from line-to-ground shock hazards because of the use of electric hand tools. There are four types of GFCIs used in the industry: Circuit breaker type Receptacle type Portable type Permanently mounted type The condition of use determines the type of GFCI selected. For example, if an electrician or maintenance person plugs an extension cord into a non-protected GFCI receptacle, the easiest way to provide GFCI protection is to utilize a portable-type GFCI.

HOW A GFCI WORKS GFCIs are devices that sense when current—even a small amount—passes to ground through any path other than the proper conductor. When this condition exists, the GFCI quickly opens the circuit, stopping all current flow to the circuit and to a person receiving the ground-fault shock. Figure shows a typical circuit arrangement of a GFCI designed to protect personnel. The incoming two-wire circuit is connected to a two-pole,

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Industrial Safety (Electrical Safety)

shunt-trip overload circuit breaker. The load side conductors pass through a differential coil onto the outgoing circuit. As long as the current in both load wires is within specified tolerances, the circuit functions normally. If one of the conductors comes in contact with a grounded condition or passes through a person‘s body to ground, an unbalanced current is established. This unbalanced current is picked up by the differential transformer, and a current is established through the sensing circuit to energize the shunt trip of the overload circuit breaker and quickly open the main circuit. A fuse or circuit breaker cannot provide this kind of protection. The fuse or circuit breaker will trip or open the circuit only if a line-to-line or line-to ground fault occurs that is greater than the circuit protection device rating.

GFCI-protected circuits is one way of providing protection of personnel using electric hand tools on construction sites or other locations.

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Industrial Safety (Electrical Safety)

SPECIAL OCCUPANCIES This section covers the specific requirements and information for installing electrical equipment and wiring in explosive and hazardous locations and underground facilities. Classifications of areas or locations with respect to hazardous conditions are discussed. Information is provided on the correct methods and techniques needed for system grounding, lightning protection, and controlling of static electricity.

EVACUATION Whenever an electrical storm approaches, personnel shall exit any location where a hazard exists from explosives being detonated by lightning. Evacuation may be necessary from locations listed below: 1. All outdoor locations, locations in buildings that do not have lightning protection, and locations within inhabited building distance of the hazard. (When an electrical storm is imminent, work with explosives operations shall not be undertaken.) 2. Locations (with or without lightning protection) where operations use electrostatic-sensitive bulk explosives or electroexplosive devices (EEDs).

SHUTDOWN OF OPERATIONS The following guidelines shall be used for shutdown of an operation during an electrical storm: 1. Process equipment containing explosives shall be shut down as soon as safety permits. 2. When buildings or bays containing explosives are evacuated, functions that cannot be shut down immediately shall be operated by the minimum number of personnel required for safe shutdown. When the operation has been brought to a safe condition, those remaining shall evacuate. 3. Automatic emergency power equipment shall be provided if electrical power is critical to an explosives operation during a power shutdown or interruption.

LIGHTNING PROTECTION Lightning protection must be installed on all facilities used for storage, processing, and handling of explosive materials where operations cannot be shut down and personnel evacuated during electrical storms. Specific operations shall be assessed for the risk of detonation of explosives by lightning.. When risk is high, as in operations with highly sensitive electrostatic materials or components, operations shall be conducted only in lightning-protected facilities

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Industrial Safety (Electrical Safety)

Lightning-protection systems should be visually inspected every 7 months and a report on their conditions filed at least annually. Any evidence of corrosion, broken wires or connections, or any other problem that negates the system‘s usefulness shall be noted and the problem repaired. Lightning protection systems should be tested electrically every 14 months to ensure testing during all seasons, or immediately following any repair or modification. The testing shall be conducted only with instruments designed specifically for earth-ground system testing. The instruments shall be able to measure 10 ohms for ground resistance testing and 1 ohm for bonding testing. Electrical resistance readings shall be recorded. Inspection records shall contain the most recent electrical test report and any subsequent visual inspection reports for each building with a lightning-protection system.

STATIC ELECTRICITY Static electricity shall be controlled or eliminated in areas where materials are processed or handled that are ignitable by static spark discharge. This category includes spark-sensitive explosives, propellants, and pyrotechnics, as well as solvent vapors and flammable gases. Approved systems to dissipate static electricity shall conform to the requirements of IEEE 142.

ELECTRICAL EQUIPMENT AND WIRING Electrical equipment and wiring in locations containing explosives shall comply with relevant provisions of the regulations, plus the requirements in this section. TESTING

Certain provisions shall be complied with before tests are performed. Qualified personnel shall be used to determine the time and procedure of the test.

TEST SETUP In setting up a test at a firing site, all preparatory work shall be completed before explosives are received. Such work shall include the following items: 1. Checking all firing site safety devices at regular intervals. Such safety devices include warning lights, door and gate firing circuit interlocks, emergency firing circuit cutoff switches, and grounding devices (including those that are remote from the firing bunker). 2. Completing all firing pad and shot stand setup work that requires power tools or other potential spark-producing devices. The firing pad shall be cleared of all unnecessary gear. Special precautions and procedures shall be developed

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Industrial Safety (Electrical Safety)

and implemented if power tools or other spark- producing devices are needed after the explosive has been received at the firing pad. 3. If a special structure is required, as much work as possible shall be accomplished on it, including assembly of all materials. 4. When possible, all diagnostic equipment shall be set up and checked, and dry runs shall be performed.

PIN SWITCHES AND OTHER NONINITIATING CIRCUITS Whenever pin switches and other non-initiating circuits are to be checked (such as for charging current or leakage) and are in contact with or close to explosives, the check shall be performed remotely. Other non-initiating electrical circuits include strain gauges, pressure transducers, and thermocouples, which may be affixed to or close to the explosives within an assembly. If a continuity-only (resistance) check is desired, this may be accomplished as a contact operation with an electrical instrument approved for use with the particular explosive device. When low-firing current actuators are involved, it may be advisable to conduct these tests remotely. LIGHTNING STORMS All operations in open test-firing areas shall be discontinued during lightning storms when explosives are present. Completion of a test after receipt of a lightning alert should be allowed only if test preparation has progressed to the extent that discontinuance of testing would represent a greater personnel risk than would completion of testing.

ELECTRICAL TESTING INSTRUMENTS FOR USE WITH EXPLOSIVES SYSTEMS Testing instruments shall meet certain criteria and be certified and labeled for the types of testing they are permitted to perform. CLASSIFICATION Testing instruments shall be assigned to categories on the basis of electrical characteristics that affect their safe use with explosives systems. Specifically, instrument categories shall be established so that testing instruments in each category can be safely applied to one or more of the following classes of explosives systems: 1.

Low-energy or hot-wire initiators (blasting caps, actuators, squibs, etc.)

2.

High-energy initiators (exploding bridgewires, slappers, etc.)

3.

Noninitiating electrical circuits.

Testing instruments that do not meet the safety criteria may be used on an explosives system only if the activity is considered a remote operation and adequate personnel shielding or separation distance is provided.

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Industrial Safety (Electrical Safety)

PREVENTION OF EXTERNAL IGNITION AND EXPLOSION Explosives are hazardous by themselves, but around electricity they become even more dangerous: an arc, spark, or hot surface can easily touch off an explosion. Therefore, the electrical installation shall contain these ignition sources or house them in an area well separated from the explosives storage area. The electrical installation shall prevent accidental ignition of flammable liquids, vapors, and dusts in the atmosphere. In addition, because portable electrical equipment is often used outdoors or in corrosive atmospheres, its material and finish should be such that maintenance costs and shutdowns are minimized. (See Figure 5-2.)

Figure 5-2. Arcs and sparks are sources of ignition that produce enough heat to cause an explosion if the air and gas mixture is between the lower and upper flammable limits of the liquid involved.

SOURCES OF IGNITION When flammable gases or combustible dust are mixed in the proper proportion with air, a source of energy is all that is needed to touch off an explosion. One prime source of energy is electricity. During normal operation, equipment such as switches, circuit breakers, motor starters, pushbutton stations or plugs, and receptacles can produce arcs or sparks when contacts are opened and closed, which can easily cause ignition. Other energy hazards are devices that produce

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Industrial Safety (Electrical Safety)

heat, such as lighting fixtures and motors. Surface temperatures of these devices may exceed the safe limits of many flammable atmospheres. Finally, many parts of the electrical system can become potential sources of ignition in the event of insulation failure. Included in this category are wiring (particularly splices), transformers, impedance coils, solenoids, and other low-temperature devices without make-or-break contacts. Non-electrical sources such as sparks from metal can also easily cause ignition: a hammer, file, or other tool dropped on masonry or on a nonferrous surface could be a hazard unless it is made of non-sparking material. For this reason, portable electrical equipment is usually made from aluminum or other material that will not produce sparks if it is dropped.

COMBUSTION PRINCIPLES The following three basic conditions are necessary for a fire or explosion to occur: 1. A flammable liquid, vapor, or combustible dust is present in sufficient quantity. 2. A flammable liquid, vapor, or combustible dust mixes with air or oxygen in the proportion required to produce an explosive mixture. 3.

A source of energy is applied to the explosive mixture.

In applying these principles, the quantity of the flammable liquid or vapor that may be liberated and its physical characteristics are taken into account. Also, vapors from flammable liquids have a natural tendency to disperse into the atmosphere and rapidly become diluted to concentrations below the lower explosion limit, particularly when there is natural or mechanical ventilation. Finally, the possibility that the gas concentration may be above the upper explosion limit does not ensure any degree of safety since the concentration first passes through the explosive range to reach the upper explosion limit.

INTRINSICALLY SAFE EQUIPMENT The use of intrinsically safe equipment is primarily limited to process control instrumentation because these electrical systems lend themselves to the low energy requirements. ANSI/UL 913- 1988 and ANSI/ISA RP12.6 provide information on the design test and evaluation.. The definition of intrinsically safe equipment and wiring is: ―Equipment and wiring that are incapable of releasing sufficient electrical energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheric mixture in its most easily ignited concentration.‖ The equipment and its associated wiring shall be installed so they are positively separated from the non intrinsically safe circuits. Induced voltages could defeat the concept of intrinsically safe circuits.

UNDERGROUND FACILITIES

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Industrial Safety (Electrical Safety)

Underground facilities consist of electrical equipment and wiring installed in underground locations. Working conditions underground can present to electrical workers hazards different from those presented above ground. This section aids in dealing with such problems. Electrical work in support of construction of mines, shafts, and underground utilities shall be performed by qualified workers. Only those workers shall install equipment and conductors within the construction activity. Once construction of the underground facilities is completed, all wiring used for construction activities shall be removed and permanent wiring installed . Electrical equipment and conductors must be used in a manner that prevents shocks and burns to people. Should electrical equipment and conductors present a hazard to people because of improper installation, maintenance, misuse, or damage, the equipment and conductors must be tagged out or locked out as a hazard until fixed. All electrical equipment and conductors shall be chosen and situated in environments conducive to their design and intended use. The voltage of bare conductors, other than trolley conductors, that are accessible to contact by people shall not exceed 50 V. Electrical equipment and conductors, other than trailing cables, shall be protected against overloads and short circuits by fuses or automatic interrupting devices used. Adequate clearance between equipment and bare overhead conductors must be maintained Conductors not being used to supply power to electrical equipment shall be deenergized and removed from their power supply or have their power supply locked out and tagged out. All exposed ends shall be insulated. Access doors and cover plates shall be closed at all times, except for installation, testing, and repair. Visible signs warning of danger shall be posted at all substations, switch centers, and control centers to warn people against entry unless they have been authorized to enter and perform duties in these locations.

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Industrial Safety (Fire Protection)

INDUSTRIAL SAFETY (FIRE PROTECTION) FIRE PROTECTION Fire Fighting, techniques and equipment used to extinguish fires and limit the damage caused by them. Fire fighting consists of removing one or more of the three elements essential to combustion—fuel, heat, and oxygen—or of interrupting the combustion chain reaction.

EXTINGUISHING THE FIRE Defense in Depth Concept: There should be arrangement that a.

Fire may not occur (Fire prevention)

b.

Fire may not spread, if occurred

c.

To extinguish fire and minimize the damage.

PREVENTING FIRES Fire prevention requires a continuous effort to keep the three conditions of the fire triangle-fuel, oxygen, and temperature from existing in the same place at the same time. We should also be careful about the usual initiating source of fire; some of which are described below:

CAUSES

OF

FIRE

Carelessness, ignorance and accident are main cause of fires. A good portion of fire prevention can be achieved through detection and elimination of following ignition sources.

Fig. 1.1 Fire Triangle

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Industrial Safety (Fire Protection)

ELECTRICAL CIRCUIT Electrical circuits are over loaded when conductor is too small for the current demand. It results in production of heat. Heat also produced while circuit is defective or faulty. Most electrical insulators materials are combustible at some temperature, which is melted when the conductor is heated. This also causes the combustible materials in vicinity to ignite. Resistance heating also occurs when electrical connections are loose or when corrosion buildup at a connection causes higher resistance and overheating. When current carrying conductors are abruptly separated, when there is a short circuit or when there is a ground fault, sparks may result. Sparks can ignite the conductor insulation material, a nearby flammable or combustible material etc. Arcing occurs when electrical energy discharge across an air gap due to a break in electrical continuity in the connection to an appliance or in switches and fuse blocks. When there is a poor electrical connection arcing and heating take place at the joint.

SMOKING Smoking is going to be a major source of ignition until it is totally eliminated in industry, work places and offices.

STEPS TO AVOID FIRE GOOD HOUSEKEEPING Is one of the most important ways of preventing fires. Piles of scrap paper, wood, oily rags, and empty solvent cans are fire hazards. A trash pile can ignite spontaneously. It can also be set aflame by a burning cigarette or by a spark or flame from a welding operation. Do not let trash and scrap accumulate anywhere in the plant. Place such materials in covered containers to keep the air out. Empty the containers regularly to prevent heat from building up inside them. Everyone can help to prevent fires by practicing good housekeeping. Isolating the fuel can help to prevent fires. Keep fuel/lubricant oil (gasoline) and such other flammable liquids in covered containers in a cool location. Fire regulations usually require such liquids to be kept in special safety rooms. The room is clearly marked almost all combustible material can form explosive dust clouds. These include light metals such as aluminum and magnesium, plastics such as polystyrene, cellulose acetate, urea formaldehyde, resins and most others, agricultural products such as flour, sugar, cocoa, coffee and dust from grain, and many miscellaneous materials and chemicals such as coal dust, wood flour, sulphur, aluminum stearate, rubber and cork dust.

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Industrial Safety (Fire Protection)

Dust also produced during milling, grinding, pulverizing, disintegrating and stamping machines. Kilns, pneumatic dryers, rotary drum dryers, spray dryers and fluidized bed dryers, conveyors and elevators of various types.

Figure.1.2 Trash container cut away

Figure.1.3 IMPROPER HOUSE KEEPING HELPS SPREAD THE FIRE

DUST EXPLOSIONS Most combustible solids in the form of a fine dust are capable of forming an explosive mixture when dispersed in air. As in the case of flammable gases and vapors, there are lower and upper dust concentrations in air within which an explosion is possible and outside which none is likely to occur. The extreme limits for a wide range of dusts are between 20 and 500 grams per liter, although the average lower explosive limit for most combustible dusts is about 40 grams per liter.

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Industrial Safety (Fire Protection)

Dust explosions generate pressures up to about 8 bar.

PREVENTING DUST EXPLOSIONS Preventing flash fires and explosions of airborne dust requires reduction or containment of the particles at the source, effective ventilation, and good housekeeping. Good housekeeping in areas that contain airborne dust means continuous clean up of all surfaces within reach. It also means periodic removal of the dust from rafters and other hard-to-reach places, and regular cleaning of dust filters and traps. The continuous cleanup of all surfaces within reach, and the removal of all trash, is the responsibility of everyone who works in a dusty atmosphere. These rooms are maintained well-ventilated, away from sources of ignition. If a fire starts inside the room, it is quickly contained by closing the fire doors. This action may even extinguish the fire by cutting off the supply of oxygen. Isolation from high temperature: is accomplished by carefully storing and handling combustible and flammable materials. Wood and proper, for example, should be stored away from boilers, furnaces, and other equipment that generates high temperatures. Controlling electrical hazards is extremely important, because so many industrial fires are electrical in origin. Effective control includes clear labeling of the purpose of all electrical circuits. Circuit disconnects, switches, circuit breakers, and fuse boxes must all be clearly marked.

PROPER ELECTRICAL

CIRCUITS

All the electrical circuits / wiring should be of proper rating and insulation resistance must be regularly checked.

MECHANISM OF FIRE EXTINGUISHMENT Fire may be extinguished by cooling the fuel, removing the oxygen and removing the fuel or inhibition of the flame.

COOLING : Cooling the fuel reduces and stops the rate of release of combustible gases and vapors. The point of fire is brought to very low temperature and is cooled down. In case solid fuels, pyrolysis is retarded and stopped. With flammable and combustible liquids, the temperature of the fuel may be lowered below its flash point (flash point for flammable liquid is below 100 degree Fahrenheit. One of the most obvious means of cooling the fuel, particularly the ordinary combustibles to extinguish a fire is through water. Water has excellent heat

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Industrial Safety (Fire Protection)

absorption capabilities. When it is applied to a fire and tuned into steam, it absorbs ambient oxygen.

EXTINGUISHMENT

BY

OXYGEN DILUTION :

Oxygen dilution, as a form of fire extinguishment, applies only to gaseous oxygen in the air and not where oxygen is available chemically. The most common extinguishing agent utilizing oxygen dilution as a means of fire Extinguisher is CO2. It provides its own pressure for application to a fire. Smothering: Smothering effect can be achieved by blanketing the fire point by the use of dry chemical powder, steam, thick layer of textiles or asbestos blankets, eliminating oxygen supply thus extinguishing fires.

EXTINGUISHMENT

BY

FUEL REMOVAL

Starvation: Fuel removal is one of the best fire preventive measures, minimizing fuel accumulation, and separating fuel from ignition sources. But once there is a fire, fuel removal or starvation is a method of extinguishment. Examples: If there is a fire in a tank of flammable liquids, the fuel (or liquid) may be pumped out of the bottom of the tank and only a small amount can be left to burn.

In case of gaseous fire, supply of gas can be shut off. Fire breaks or fuel clean areas can be plowed in bush forest fire areas to stop the spread of fire. House keeping is a mean of minimizing the amount of combustibles

CLASSIFICATION OF FIRE When selecting extinguishing agents for first aid fire fighting or automatic fire control systems, the effectiveness of each agent should be evaluated with regard to specific application. Those agents should be selected which are most effective, safe and best suited to the particular operation or equipment.

CLASS-A Ordinary combustibles such as wood, paper, cloth and plastics, which when burning, require the cooling and quenching effect of water, a solution of water or the blanketing effect of multipurpose dry chemical agent.

CLASS-B

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Industrial Safety (Fire Protection)

Flammable liquids fires such as gasoline oil, paints, flammable gases, and solvents which require blanketing, smothering or chemical inhibition agent.

CLASS-C Electrical fires which require a nonconductive fire extinguishing agent with cooling, smothering, chemical inhibition characteristics.

CLASS-D Combustible metal fires such as magnesium (Mg), aluminum (AL), sodium (Na), potassium (Mg), sodium/potassium alloy, lithium (Li), Zirconium (Zr), titanium (Ti), and Uranium (U), which require special dry power extinguishing agent, which blanket the fire and exclude oxygen while being immune to the tremendous heat of combustible metal fire.

FigURE 1.5 Symbols of fire types

FIRE EXTINGUISHERS Fire extinguishers can be divided into five main groups, depending upon the extinguishing agent they contain. They are water, foam, carbon dioxide, dry chemical powder and steam. Each type is briefly described below.

WATER EXTINGUISHERS There are three types of water extinguisher.

WATER (GAS

PRESSURE

& TROLLEY MOUNTED )

This type of extinguisher consists of a cylindrical or conical container filled to an indicated level with water. Non-corrosive anti-freeze agents, non-corrosive welting agents or corrosion inhibitors are some time added to the water. The gas required for expelling the water is stored in a cartridge fitted with a sealing device which is pierced when the extinguisher is operated. The nozzle is attached to the body of extinguisher or to the end of a length of hose. Some nozzles can also be adjusted to give a jet or spray.

WATER (STORED PRESSURE) This type of extinguisher consists of a cylindrical container filled to an indicated level with water. The water is expelled by air or inert gas permanently stored in

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Industrial Safety (Fire Protection)

the same container. The nozzle is attached to the body of the extinguisher or to the end of a length of hose.

WATER (SODA ACID) This type of extinguisher consists of a cylindrical or conical container filled to an indicated level with a solution of sodium bicarbonate in water. A glass bottle or plastic bottle fitted in a cage is filled with sulphuric Acid. When the extinguisher is actuated, the acid is released from the bottle and reacts with the solution to produce the gas which expels the water. The nozzle is attached to the body of extinguisher or to the end of a length of hose.

FOAM EXTINGUISHERS There are two types of foam extinguishers.

FOAM (CHEMICAL) This type of extinguisher consists of a cylindrical container filled to an indicated level with a solution of sodium bicarbonate in water, together with a stabilizer. An inner container is filled with a solution of aluminum sulphate in water. When the extinguisher is actuated the two solutions are mixed and the resultant chemical action produces the foam and gas which acts as the expellant. The nozzle is attached to the body of the extinguisher. The volume of foam produced is about eight times the capacity of the extinguisher which is usually 1 to 2 gallons.

FOAM (MECHANICAL ) This type of extinguisher is similar in construction and capacity to a foam (chemical) extinguisher but the foam compound is stored either as a solution in the body of extinguisher or in a hermetically sealed inner container. The foam is expelled by a gas which is stored in cartridge. The nozzle is attached either to the body of the extinguisher or to the end of a length of hose. The volume of foam produced is about eight times the capacity of the extinguisher, which is usually 1 to 2 gallons.

CARBON DIOXIDE EXTINGUISHERS This type of extinguisher consists of a cylindrical container filled with liquid carbon dioxide to approximately 2/3 of its capacity and fitted with a sealing disc and piercing device or a valve. A special discharge horn is also fitted either to the valve or to the end of a length of hose. Some horns are fitted with a shut-of control. The horn is a distinctive feature of this extinguisher and provides a means of directing the gas on the fire. Portable models are available in various sizes up to 15 lbs capacity.

DRY C HEMICAL POWDER EXTINGUISHERS This type of extinguisher consists of a cylindrical container to a certain level with a dry power. The expellant gas is stored within the extinguisher body (when it is known as a ―stored pressure‖) or in a cartridge. The nozzle is attached either to

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Industrial Safety (Fire Protection)

the body of the extinguisher or to the end of a length of hose. Some nozzles are fitted with a shut-off control. Portable models are available in various sizes up to 30 lbs capacity.

FIRE BUCKETS These can be filled with either water or sand. They can be metal or plastic and usually of 2 gallon capacity. They have a flat or round bottom. The advantage of the flat-bottomed bucket is that two buckets can be carried to a fire and one put down while the other is being used. This is not possible with the round bottomed buckets. On the other hand the round-bottomed buckets cannot easily be used for purposes other than these for which they were intended. They are thus more likely to be in place and ready for use when required for fire fighting.

MANUAL FIRE PUMPS These consist of a hand pump rigidly mounted in a metal container and fitted with a length of hose terminating in a nozzle (usually 1/8‖ dia). The capacity of the container should not be less than 2 or more than 3 gallons. The pump should be capable of throwing a jet at least 30 ft. Although they can be operated by one person, three are preferable, one to pump, one to manipulate the hose and direct the jet and one to replenish water supplies.

PORTABLE DRY POWDER EXTINGUISHERS Portable dry powder extinguishers are made with capacities from 2 to 10 kg of powder. Their range is less than a water extinguisher, usually from 3-6m. These are the best type of extinguisher for dealing with fire of flammable liquids. They extinguish the flames over the liquid and thus act faster than foam. They can deal with larger areas of burning liquid than other extinguishers of the same size, and they are effective on fires of flowing liquid. Dry powder can be safely used on electric fires. The main limitation of dry powder is that it gives no protection against re-ignition after application ceases, since it has poor quenching properties. It is less effective than foam on liquid fires where the liquid has become overheated (i.e. through prolonged burning). Two kilograms of dry powder can normally extinguish a liquid fire covering an area of one square meter when properly applied.

PORTABLE CARBON DIOXIDE EXTINGUISHERS Carbon dioxide extinguishers should only be used sparingly in buildings due to the dangers of asphyxiating personnel. A second hazard of carbon dioxide extinguishers is the formation of static electricity in the discharge which can ignite flammable vapors, sometimes with fatal consequences. Carbon dioxide acts more rapidly than foam and is more suitable for dealing with fires which might spread to surrounding materials before a complete foam blanket could be formed over the burning liquid. Carbon dioxide extinguishers are suitable for dealing with small fires of liquids flowing over horizontal and

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Industrial Safety (Fire Protection)

vertical surfaces. They should be used where the main concern is to avoid damage or contamination by dry powder deposit or foam, for example to laboratory equipment or food preparation. Cooling property of carbon dioxide is limited and it gives no protection against re-ignition after application ceases. It is less effective than foam for very hot liquids burning in containers. Carbon dioxide extinguishers contain the carbon dioxide under high pressure as a liquid in steel cylinder, with a valve leading via flexible hose to a horn shaped discharge tube.

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Industrial Safety (Fire Protection)

USE OF FIRE EXTINGUISHER FOR USE

ON

FIRE

IN

ORDINARY COMBUSTIBLE MATERIALS (CLASS ‗A‘ FIRES )

The effectiveness of an extinguishing agent on a fire in ordinary solid combustible materials (e.g., Wood, Paper, Textile, Fabrics etc) depends upon its cooling action. As water has better cooling properties than other extinguishing agents, it is the best agent for class ‗A‘ fires which may be liable to re-ignite if not adequately cooled. In addition water can penetrate readily to reach a deepseated fire. Suitable and available extinguishers are:

FOR

SMALL FIRES

Water (Gas pressure) Water (Soda/Acid) 2 Gallon buckets

FOR

LARGE FIRES

Fire fighting vehicle Fire hydrants Fixed systems

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Industrial Safety (Fire Protection)

FOR USE

ON

FIRES

IN INFLAMMABLE

LIQUIDS (CLASS ‗B‘

FIRES )

Small contained fires can be extinguished by covering them with a lid or an asbestos blanket. Sand can also be useful for dealing with fires in small quantity of spilled liquid. Flammable liquid fires cannot normally be extinguished by water. Suitable types of extinguishers for this class of fire (e.g., in oil, lubricants etc.) are:

DRY POWDER. Foam (Chemical/Mechanical) type. Dry powder is probably the most suitable type of extinguisher for dealing with fires in flammable liquids, but there are circumstances to which one of the other types may particularly be suited. The cooling properties of dry power are limited and it gives no protection against re-ignition which may occur after application ceases. It is not as effective as foam on fires in liquids in container where the liquid has over heated either because it has been burning for sometime or because it has been heated in a process. It should be remembered that portable fire extinguishers are intended for drilling with relatively small fires. For the protection of large risk, equipment of greater capacity such as mobile extinguishers and fixed installation are required. Carbon dioxide, by extinguishing the flames over the liquid, acts more rapidly than foam and is more suitable for dealing with fires which may spread to surround metals before a complete foam blanket can be formed over the burning liquid; however CO2 extinguishers are suitable for small fires involving escaping of liquid on both horizontal and vertical surface.

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Industrial Safety (Fire Protection)

FOR USE

ON

FIRES

IN

GASES (CLASS ‗C‘

FIRES )

Method of starvation (cutting of the supply of gas if possible) should be applied. Appropriate type of fire extinguisher should be used.

FOR USE

OF

FIRES

IN I NFLAMMABLE

LIGHT METALS

Complete blanketing of burning materials required. Dry powder type fire extinguisher may be used.

FOR USE

OF

FIRES

IN

ELECTRICAL SYSTEM (CLASS ‗C/E‘

FIRES )

For example fire in lire electrical equipment. Co2 type fire extinguishers may be used. However, in case of high voltage Dry powder is a non-conductor of electricity and can safely be used on fires where there is a risk of electric shock. Caution must be exercised in fighting fires in or near live high voltage electrical equipment. In such cases a fog spray only must be used with the straight and fog type nozzle.

FOR USE

ON

FIRES

INVOLVING

ELECTRICAL

AND

ELECTRONIC EQUIPMENT

Carbon dioxide and dry powder extinguishers are mot suitable for dealing with fires involving electrical equipment. Where live electrical equipment may be involved extinguishers containing water or foam (which are conductors of electrically) should not be used, because of the risk of shock. Where however, it is possible to cut off the circuit, water, which is the most efficient extinguishing agent for these fire, can be use, unless oil or other flammable liquids are involved, in which case the fire should be treated as a flammable liquid fire and deal with as earlier described. Although dry sand may also be used on small fires in electrical equipment its use on machinery is not advisable because of its abrasive nature. Carbon dioxide extinguishers are most suitable for dealing with fires involving electronic equipment, in view of the delicate nature of such equipment.

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Industrial Safety (Fire Protection)

HOW TO USE EXTINGUISHERS It is essential all persons who may have to use extinguishers should receive instruction and training in the handling and operation of the equipment installed and have some elementary knowledge of proper fire-fighting techniques.

INSTRUCTION

AND

TRAINING

The object of instruction and training should be to eliminate delay brought about by hesitation and unsuccessful attempts to operate the extinguisher. Training can be given either individually or in group. Routine maintenance provides an ideal opportunity, particularly when extinguishers have to be discharged as part of the maintenance procedure. The suppliers of the equipment or the local fire brigade may be willing to assist. Where more than one type or model of extinguisher is provided, special instruction should be given to help persons to select the right type of extinguisher for dealing with the fire and to use the correct method of operating the particular model of extinguisher provided. An extinguisher will not operate unless the correct method is used.

Guidance on suitable techniques for fighting fire with the various types of extinguisher is given below.

ATTACKING

A

FIRE

Take up a position where access to the fire is unrestricted but where a quick and safe retreat is possible, e.g., on the side of the fire nearest a door or when outside a building, windward of the fire. A crouching attitude will help the operator to keep clear of smoke and avoid heat, and thereby permit a closer approach to the fire. Care should always be taken to ensure that a fire is completely extinguished and not liable to re-ignite or continue smoldering.

WATER EXTINGUISHERS Direct the jet at the base of the flame and keep it moving across the area of fire. Seek out any hot spots after the main fire is extinguished. A fire spreading vertically should be attacked at its lowest point and followed up.

FOAM EXTINGUISHERS Where the liquid on fire is in a container, direct the jet at the inside edge of the container or at an adjoining vertical surface above the level of the burning liquid. This breaks the jet and allows the foam to build up and flow across the surface of the liquid.

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Carbon dioxide extinguishers are especially suitable where the over-riding factor is to avoid damage or contamination by dry powder deposit or foam. The cooling properties of carbon dioxide are limited and it gives no protection against re-ignition which may occur after application ceases. It is not as effective as foam on fires in liquids in containers where the liquid has overheated either because it has been burning for some time or because it has been heated in a process. Carbon dioxide is a non-conductor of electricity and can safely be used on fires where there is a risk of electrical shock. Examples of risks where carbon dioxide extinguishers are especially suitable.

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Industrial Safety (Fire Protection)

INSTALLATION PLACING OF

APPLIANCES

Extinguishers and other appliances should be placed in conspicuous positions readily accessible for immediate use. Generally speaking, they should be positioned as near as possible to exits, or on stair case landings. It is not advisable to position them at the end of a room where there is no exit, unless they are there to protect a particular hazard. Extinguishers installed to protect such special risks should not be placed too close to the risk for safe access, should a fire occur. In any event, extinguishers and other portable appliances should be positioned within 100 ft. of one another. Where large undivided floor areas necessitate positioning appliances away from exits or outer walls, they should be installed on escape route. Extinguishers and other portable appliances should be placed on brackets not more than 3 ft. 6 inch. from the floor or low shelves not more than 2 ft. 6 ins. from the floor, where they are conspicuous and can be collected without difficulty in the event of fire. They are less likely to be damaged if raised off the floor. When on the floor they should be kept in position in boxes. Water and foam extinguishers are liable to be affected by low temperatures. This applies especially to water (soda/acid) and foam (chemical) extinguishers which should not be sited where they may be exposed to low temperatures. With water as pressure, water (stored pressure) and certain types of foam (mechanical) extinguishers a non-corrosive anti-freeze agent may be used as an alternative, to protect them against freezing. High temperatures may lead to the rupturing of carbon dioxide and stored pressure type extinguishers. Gas cartridges of gas-expelled extinguishers may also rupture. The suppliers should be consulted if the temperature of rooms where extinguishers are to be installed is likely to exceed 110 F (43 C). Fire points should be distinctly indicated. Descriptive notices should be posted at important places.

CARE AND MIANTENANCE It is most important that portable fire appliances should be kept in their allotted positions and not be misused. The provision of brackets, shelves or base blocks will assist detection if any appliance is missing. Extinguishers should be recharged in accordance with the supplier‘s instructions immediately after they have been completely or partially discharged. One refill for each extinguisher should always be kept available for this purpose.

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Inspection and testing by the suppliers or firms specializing in this work is recommended. This can also include periodical reconditioning if found necessary. The date of inspection should be recorded on a label securely attached to the extinguisher or painted on the body (it should not be stamped into the body of the extinguisher). Alternatively, the date may be recorded in a special register; each extinguisher should have an identification to correspond with the item in the register. The periodical pressure testing of extinguishers other than carbon dioxide extinguishers is not longer considered necessary. But any extinguishers showing sings of internal or external corrosion or damage should be taken out of service and replaced. After extinguishers have been discharged at the intervals recommended below they should be thoroughly examined internally for corrosion using an illuminated probe.

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Industrial Safety (Fire Protection)

INSPECTION AND TESTING OF EXTINGUISHERS WATER (GAS PRESSURE ) Water (gas pressure) extinguishers should be opened up annually and the following checks made: The extinguisher is filled to the correct level. The nozzle, internal discharge tube and strainer, snifter valve and vent holes in the side of the cap are not clogged. The plunger moves freely. The cap joint washer and the hose are in good condition. The gas cartridge is weighted to defect any loss and if this exceeds 10 per cent of the weight of he contents the cartridge should be replaced. The sealing washer should also be checked ensure that it is in good condition. Every extinguisher should be discharged at least once every five years.

WATER (STORED PRESSURE) As these extinguishers are pressurized they may only be opened for inspection after discharge. They should be discharged and opened up annually and the following checks made.

SEE THAT : The extinguisher is pressured correctly by examining the indicating device or tell tale indicator both before and after discharge. The nozzle, internal discharge tube and strainer and vent holes in not clogged.

the cap are

The operation mechanism is in good order. The cap joint washer and hose are in good condition. No corrosion is visible internally or externally.

WATER (SODA /ACID) Water (Soda/Acid) extinguishers should be opened up annually and the following checks made.

SEE THAT : The extinguisher is filled to the correct level. There has been no acid leakage which can be caused by seepage past the lead stopper in the case of some turn over models, or which may be the result of a

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cracked bottle. (Cracked bottles should be replaced) if leakage has occurred the extinguisher should be recharged. The nozzle, internal discharge tube and strainer, snifter valve and vent holes in the side of the cap are not clogged. The plunger or hammer moves freely. The cap joint washer and the hose are in good condition. No corrosion is visible either internally or externally. Each extinguisher should be discharge at least once every five years. Turn over models (open acid bottle), however, should be discharge every two years. After discharge, extinguisher should be thoroughly washed out with clean water and any places of glass or solid matter removed.

FOAM (CHEMICAL ) Foam (chemical) extinguishers should be opened up annually and the following checks made.

SEE THAT : The extinguisher and inner container are filled to the correct level. The nozzle, internal strainer and vent holes in the side of the cap are not clogged. The releasing device moves freely. All washers are in good condition. No corrosion is visible either internally or externally. It is not necessary to strip the contents (of this type of extinguisher and stirring may, in fact, cause damage. Every extinguisher should be discharge once every two years. After discharge, extinguishers should be thoroughly washed out with clean water and any solid matter should be removed.

FOAM (GAS PRESSURE) Foam (Gas Pressure) extinguishers should be opened up annually and the following checks made.

SEE THAT : The extinguishers is filled to the correct level. The nozzle, internal discharge tube and strainer, snifter valve and holes in the side of the cap are not clogged. The plunger moves freely.

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The cap joint washer and hose are in good condition. No corrosion is visible internally or externally. The gas cartridge is weighted to detect any loss and if this exceeds 10 percent of the contents the cartridge should be replaced. The sealing washer should be checked to ensure that it is in good condition Extinguishers should be discharged at least once every two years, or once every four years in the case of extinguishers where the foam compound is in a sealed container.

CARBON DIOXIDE: Carbon dioxide extinguishers required rather different maintenance from most other types of extinguisher. At least once every twelve months, the extinguisher should be weighted and the body inspected for external corrosion. If a loss of weight, indicating that leakage is occurring, or extensive corrosion is detected the extinguisher should be hydraulically tested by the supplier or a specialist firm. This test should be repeated there after at intervals of five years. If no such loss or corrosion is detected it is necessary for a hydraulic test to be carried out every five years. In the event of an extinguisher being discharged during the first 10 years, however, the same condition apply as when leakage or corrosion is detected. In addition to the checks mentioned above the following checks should also be made.

SEE THAT : The horn, hose and valve assembly are in good condition. The squeeze grip horn control moves freely. (Do not confuse this with the actuating mechanism on the valve assembly)

VAPORIZING LIQUIDS Vaporizing liquid extinguisher should be checked annually as follows:

STORED GAS PRESSURE

AND

AIR PUMP STORED PRESSURE MODELS

These models cannot be opened up for inspection. They should therefore be weighed and if a loss of weight is detected the suppliers or a specialist firm should be consulted. Some models are fitted with a pressure gauge which gives rapid check, but the extinguisher should, nevertheless, still be weighted as gagues are not always accurate. The following checks should also be made.

SEE THAT : The nozzle is not clogged.

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Industrial Safety (Fire Protection)

No corrosion is visible externally. Every extinguisher should be discharged at least once every five years.

GAS C ONTAINER MODELS These models should be opened up and the following checks made.

SEE THAT : The extinguishers is filled to the proper level. The nozzle, internal discharge tube and strainer, and vent holed in the side of the cap are not clogged. The plunger or other operating device is free to move. The cap joint washer and the hose are in good condition. No corrosion is visible internally or externally. The gas cartridge is weighted to detect any loss and if this exceeds 10 percent of the weight of the contents the cartridge should be replaced. The sealing washer should also be checked to ensure that it is in good condition. Every extinguisher should be discharged at least once every five years.

HAND PUMP MODELS INCLUDING AIR PUMP TRANSIENT PRESSURE MODELS. The following checks should be made.

SEE THAT : The nozzle is not clogged. The hose, if any, it in good condition. The pump mechanism is in proper working order. This can be checked by making or two strokes with the nozzle pointing in both an upward and down ward direction. The handle should then be returned to the ―locked‖ position. No external corrosion is visible. The pressure used for hydraulic testing varies according to the kind of steel used for the body of a carbon dioxide extinguisher.

DRY POWDER Dry Powder extinguishers should be checked annually as follows:

STORED PRESSURE MODELS. These models cannot opened up for inspection. They should therefore be weighed as a check against loss of powder, and if a loss of weight is detected the supplier or a specialist firm should be consulted. Some models are fitted with a

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pressure gauge which gives a rapid check but the extinguisher should, nevertheless, still be weighed, as gauges are not always accurate. The following checks should also be made.

SEE THAT : The hose is in good condition. The nozzle is not clogged and the squeeze grip nozzle control moves freely. (Do not grease or oil this control). No corrosion is visible externally. Every extinguisher should be discharge at least once every five years.

GAS

CARTRIDGE MODELS .

These models should be weighed to check that they are filled with the correct quantity of powder. They should be opened up annually and where a discharge control is fitted on the nozzle at the end of hose, this should be operated before opening to relieve any pressure which may be present. The following checks should ten be made.

SEE THAT : The nozzle internal discharge tube, snifter valve and vent holes in the side of the cap are not clogged. The cap joint washer and the hose are in good condition. No corrosion is visible externally. The plunger and the squeeze grip nozzle control move freely. (Do not grease or oil this control). The powder is free form caking. All washer and hose are in good condition. Tue gas cartridge is weighed to detect any loss and if this exceeds 10 percent of the content the cartridge should be replaced. Every extinguisher should be discharged at least once every five years. They should be kept preferably dry after being discharged and not washed out. In addition, every extinguisher should be examined monthly to check for loss brought about by evaporation, ―topped up‖ where necessary. Every extinguisher should be discharged annually. When the periodical discharge of gas container and hand pump models is being carried out the liquid can be poured into a suitably large clean earthenware or

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glass vessel can be used for recharging the extinguisher which should then be ―topped up‖ Portable Manual Pumps. At monthly intervals the pump should be examined to see that it is filled with water after which it should be discharged. The following checks should then be made.

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Industrial Safety (Running Nips)

INDUSTRIAL SAFETY (RUNNING NIPS) DEFINITION In manufacturing process today we have gone some way towards complete automation – a phrase conjuring up visions of totally enclosed and completely safe operations. In the interim we see more and more continuous operations introduced – long lines of machinery manipulating the product to its final shape. Unfortunately, most of these long lines are not totally enclosed and it is in this type of machinery, using multitudes of rollers and conveyors, that thousands of running nip hazards are created. The running nip occurs where a material runs on to, or over, a roller or similar device. A conveyor running over a roller creates a nip; material being wound on to a roller creates a nip; there are in-running nips between rolls on process machinery such as calendars and two-roll mills; nips on transmission machinery such as those created by flat belts or V-belts running over pulleys; and nips created between chains sprockets or between gears. We will deal here with those aspects of the problem which have required special study in the rubber industry: conveyors, materials winding onto rollers, two-roll mills, and calenders. There is some disbelief that a piece of material running over a roller can be dangerous – an attitude of mind not unlike that often found towards the seemingly innocuous revolving shaft. This may be an over-simplification, but a study of the number of unguarded nips which exist and of accidents which have occurred shows more than ample evidence of an appalling ignorance of the hazard among management and men alike. This type of accident is particularly distressing, for in most cases the result is mutilation; in many instances, when a man is caught in a nip, he is carried off his feet and may suffer additional injuries through contact with the floor or other fixed objects.

TYPES OF ACCIDENTS A study of ‗nip‘ accidents involving lost time in the rubber industry showed that the nips occurred in many different locations: between belt and powered rollers, belt and idle rollers, belt and framework or endplate, nips between bowls, between material and bowls, between sheets of material and even in one case between the bowl and the ‗safety bar‘! The particular causes were varied and included:

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Industrial Safety (Running Nips)

(a) inadvertent starting. (b) straightening of material, including tucking-in torn edges. (c) clothing caught. (d) slipping and falling into an unguarded nip. (e) removing foreign bodies or jammed stock. (f) cleaning rollers whilst in motion.

CONVEYOR BELT NIPS The common conveyor system takes a large toll and yet is probably the easiest running nip hazard to guard. It is possible to standardize the design to some extent; this is most easily demonstrated by reproducing a drawing used as a reference for plant engineers (Fig. 4.1).

FIGURE NO. 4.1, THIS DIAGRAMMATIC ARRANGEMENT SHOWS HOW A MAN COULD BE TRAPPED BETWEEN THE ROLL AND THE FLOOR WHERE THE REELING TAKES PLACE TOO CLOSE TO THE FLOOR. IT IS A SIMPLE MATTER TO RAISE THE MOUNTING OF THE ROLL

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Industrial Safety (Running Nips)

With a little ingenuity all conveyors can be guarded, but they require frequent maintenance and adjustment. It is necessary in designing a guard to keep in mind the points of access required; otherwise it may be found that the guards are so damaged or distorted through constant removal and refitting that eventually they are left off altogether.

NIPS BETEEN MATERIALS AND ROLLERS The more complex problem of material being wound on to a roller is intrinsically a running nip. This, unfortunately, is only the beginning of the matter; the material being wound up creates a nip of ever-changing position in a radius which is increasing all the time. The periphery of the batch can in these circumstances continually create another nip between itself and a fixed structure. Prior to the batching up it is inevitable that the material will have passed over or under a number of rollers which exist to maintain a certain tension in the material. Even if such rollers are not power driven, a dangerous nip can be created between the material and the roller at the point at which they meet. The ‗nip‘ as an injury-creating situation exists at some point prior to the two surfaces actually coming into contact, e.g., the thickness of a finger. A further complication increases the hazard when material are being used as lines for other sheet material being processed. For instance, in the rubber industry linings are often used to give backing to rubber or rubberized fabrics being processed. The hazard is thus increased. The most obvious method of minimizing the risk of a running nip accident is to arrange that the material runs over the top of the roller wherever possible, thus confining the hazard to the sides of the nip. With this arrangement no one can fall into the nip.

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Industrial Safety (Running Nips)

Where a series of rollers occur in rapid sequence they are perhaps easiest to deal with by fixed guards which enclose the side sections of the machines, because it is difficult to guard each one in such a way that nobody can gain access, whether they are the operators or simply people passing the machine who could slip and fall against it. Individual nips between material and fixed roller, where regular access may be required or which are close to other parts of the machine which must be accessible, are best protected by the interlock type of guard. It is important with all interlocks that access is prevented until the machine has come to rest. This necessitates a good braking system, and may require the installation of mechanisms which will delay the removal of the guard until the machine has come to rest. Another type of protective device used in these circumstances is the photoelectric cell which is dependent upon the interruption of a light beam; but in such cases the machinery should be slow moving and must stop instantaneously (Fig 4.2). In the cases of both interlocked guards and the photoelectric cell, it is important to ensure that any failure of a mechanical or electrical nature will cause the machine to stop. In all cases the guard must be such that the operator cannot circumvent it and thus defeat its purpose. The greatest problems occur when material is being handled at the feed or takeoff ends, and it is particularly severe when a new reel is being started because the operator is virtually creating a nip with his own hands. The best method of dealing with this part of the problem is to use a festoon of material

FIGURE NO. 4.2, THIS DIAGRAM SHOWS THE POSITION OF THE LIGHT PROJECTOR AND THE CELL RECEIVER, WITH THE BEAM PASSING ALONG THE FRONT OF THE NIP.

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Industrial Safety (Running Nips)

which creates a reserve at both feed and take-off and, therefore, permits continuity of running whilst the reels at either end are stationary. This means that they can be changed in complete safety. In plant of this type the whole train of machinery should be kept continually threaded with a band of material. In single batch runs, materials may have to be threaded through a number of rollers, and devices should be provided for inching or very slow running. A useful starting up device consists of a pair of suitable short tapes attached to the corners. These, when fitted on to each end of the liner, enable the machine attendant to commence the batching operation with out presenting his hand to the actual nip. Having effected one complete turn the tapes may then be disposed of by being thrown into the second turn. It is also recommended that the fullest use should be made of leaders and followers for connecting interrupted batches. This practice is very well known and can serve a most useful purpose by permitting the installation of fixed guards. Another device used is to encage the whole of the end section on a sensitive floor which is interlocked so that the machinery stops as soon as anyone steps on to the boards in front of the batching nip. (Although not directly related to the problem of ‗nip‘ accident it is worth noting that the rolls must be securely mounted to prevent their jumping out. A falling roll is itself a serious hazard.) Strict training in job methods and follow-up by supervision are vital aspects of combating the running nip problem but, since the human element is not always entirely reliable, they should not be regarded as satisfactory substitutes for safe conditions. Operators have frequently been drawn into nips whilst straightening running material or even just touching it for no apparent reason. There are several straightening devices which will help to obviate these dangers. It is also wise to insist that liner materials be removed if the edges are frayed or torn. Apart from the nip of infinite radius created by material batching upon a roller, the rubber industry has long experience of nips of finite radius at machines consisting of two or more large steel rollers running together, and it is known that this type of machinery has application in other industries. It is possible therefore that a description of two particular machines – the horizontal two-roll mill and the calendar-will offer guidance which can be useful in a much wider range of applications.

TWO-ROLL MILLS The two-roll mill consist of two rolls situated side by side in a horizontal plane through which rubber is squeezed into sheet form. Normally these rolls vary in diameter from about 400 mm upwards to about 700 mm. The nip between the two rolls has been a source of many accidents in the past – all of them serious

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Industrial Safety (Running Nips)

and some of them fatal. It was demonstrated that it was possible to erect a sensitive safety barrier so placed that, if an man was entangled in material on the mill, his body would be pulled towards the mill and he would involuntarily actuate the barrier, which itself would operate a brake to stop the machine within such distance that the man could not possibly be pulled into the nip (Fig 4.3). In other words, although an ‗accident‘ could occur, there could be no injury. This in fact is now the accepted standard method of guarding the two-roll mill. To arrive at a solution offering complete safety a number of problems had to be solved, the main one being to create a state in which a man could still work comfortably at the machine, the normal job being to cut off sheeted rubber from the face of the roll. There must be a limited distance which the roll may travel after actuating the brake if the operator is not to be drawn into the nip if he becomes entangled in the material being worked. The first requirement therefore is rapid braking, following the important criterion that the shorter the stopping distance, the greater the safe working accommodation available on the mill. Allowing for a finger gap of 20 mm prior to the actual nip, one can determine a point beyond which the operator must not be able to reach before actuating the brake. The location of the sensitive safety bar is fixed, therefore, with regard to the operator‘s reach (Fig. 4.3). It has been found necessary in existing installations to excavate a pit in front of the mill to achieve this condition. On the other hand, new mills are raised to secure the same conditions – that of taking the danger zone further away from the man.

FIGURE NO. 4.3 DIAGRAMMATIC SIDE VIEW OF A TWO-ROLL MILL SHOWING THE POSITION OF THE SENSITIVE SAFETY BAR RELATIVE TO THE SAFETY LIMIT.

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Industrial Safety (Running Nips)

Having taken this practical care, one must then ensure that the operator cannot gain access either over the bar or under it, and this means removing footholds and enclosing the area under and at the sides of the safety bar. Care must be taken to avoid creating a nip between the safety bar and the fixed guards adjacent to it. It will be seen that the whole principle is based upon the relative dimensions of the man to his machine. Having established the location of the safety bar on the machine, no operator may work at it if he can reach beyond the safety limits, and this test must be established and recorded for each man concerned.

1.1.

WORKING ON BACK ROLLS

Some mills are required to be worked on the back as well as the front roll. In such cases sensitive safety bars must be fitted at both locations. It will be obvious that where, due to unequal gearing or different diameters, the rolls run at different surface speeds, the position of the safety limit on the back roll will not be the same on the front. If work on the back rolls is not required then this area must be enclosed with interlocking guards to deny access when the mill is working. It is necessary to conduct regular tests of the braking distance and of the pressure required to operate the sensitive safety bar (a horizontal pressure of about 16 kg has been found to be a satisfactory loading), and written records should be kept of these tests. It should also be standard routine for the bar to be tested at the beginning of every shift to prove that the mechanism is in working order.

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Industrial Safety (Running Nips)

Laboratory mills, the rolls of which have a relatively small diameter, cannot be guarded in the same fashion. The most practicable type of guard prevents access from above the nip when feeding rubber into it. Where the guard lies adjacent to the face of the roll, there are ‗knuckle‘ controls which will actuate the brake if the hands are pulled against them. Again good braking is essential.

CALENDERS This is a much more complex problem and no common solution is possible because of the varying number of rolls and the varying ways in which they are arranged. The problem is even further complicated if the machine is capable of operating in reverse. Many calenders nowadays can operate at high speeds and can be set to produce very fine sheets of uniform thickness. They require many additional devices such as gauges for controlling thickness etc., and all these factors tend to complicate the fitting and operation of guards.

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Industrial Safety (Running Nips)

1.2.

FEED NIPS

As always the fixed guard is of course the most reliable (Fig. 4.5), but this is only convenient when feed methods do not change from process to process and

FIGURE NO. 4.5, FIXED GUARDS: A SIMPLE SYSTEM OF FIXED PARALLEL BARS; THE BARS MUST BE STRONG AND SUITABLY MOUNTED TO PREVENT SPREADING. SHEET RUBBER COMPOUND IS FED BETWEEN THE BARS; A SMALL HORIZONTAL TABLE SUPPORT IS SHOWN.

the rubber is delivered in sheet form. Unfortunately, feeding stock to a calender is not always so simple; consequently, the guards have to accommodate bulk but at the same time they must keep the operator at a safe distance. One

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Industrial Safety (Running Nips)

method is to feed over a fixed distance board with a sensitive safety bar between the board and the operator. The tunnel guard is another method of feeding; it does require that the tunnel is of adequate length to protect men with exceptional reach. It is usually necessary to provide a push stick (Fig 4.6). The manger guard is a similar distance guard and is used at heights over which the operator cannot normally reach. The guard is in the shape of a manger presented to the face of the rolls and rubber is fed into it. The rubber is assisted into the nip using a push stick between the grill bars of the guard. The push stick must be fitted with a hilt which limits the extent to which it can reach towards the nip. Many manger guards are simple fixed fences but refinements have been introduced to make the guard pivot about its axis with trips to limit the amount of movement towards the nip in order to prevent access to the danger zone from the top of the manager. Because the shelf at the bottom of the manger must be clear of the roll surface to permit vertical adjustment, only the minimum clearance should be permitted so that fingers are not trapped between the edge of this platform and the roll surface. Upward movement of the platform also applies the emergency brake.

The simplest and safest method of feeding is that done automatically either by direct gravity conveyor or by a pendulum conveyor moving backwards and forwards across the face of the roll. This introduces extra machines and thus extra hazards, not least of which is the danger of a nip between the pendulum moving to and fro and fixed parts of the calender.

1.3.

OTHER CALENDER NIPS

On nips away from the feeding point, two types of guard can be used. A fixed guard is desirable but it is not always possible to present it close to the face of the roll because of the varying thickness of material being processed and the danger or trapping between the guard and the roll. In these circumstances the guard has to be supplemented with knuckle trip bars at the two points nearest to the faces of the rolls. (Fig 4.7). The ‗loop‘ guard consists of a series of grille bars presenting a side view shaped like a loop. If the fingers approach too closely to the nip they can be moved to a position between the loop bars and withdrawn. The loop has limited movement

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Industrial Safety (Running Nips)

up and down and it is set to trip the brake if pressure is exerted between the roll and the loop bars. An important feature of operator protection using all these guards is the braking system. All modern machines can and should be fitted with highly efficient brakes which can stop the machine rapidly without damage even when it is operating at high speed.

FIGURE NO. 14.6 TOP ‗NIP‘: THERE IS A LONG TUNNEL GUARD OVER THE FEED TABLE WITH A TRIP BAR TO STOP THE MACHINE, IN FRONT OF, AND SLIGHTLY BELOW THE EDGE OF THE TABLE. BOTTOM ‗NIP‘: A STRONG LOOPED GUARD EXTENDS ACROSS THE CALENDER; THE LOOPS ARE SUFFICIENTLY CLOSE TO THE ROLL AND SO SPACED AS TO PREVENT ACCESS TO THE NIP. THE LOOP HAS LIMITED MOVEMENT UP AND DOWN AND MAY INCORPORATE A DEVICE TO OPERATE THE BRAKES.

]

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Industrial Safety (Running Nips)

FIGURE NO. 4.7 FIXED GUARDS AND KNUCKLE CONTROLS

The threading of calenders can be a hazardous operation, and should only be undertaken by experienced men. However, the hazards can be eliminated or reduced by the use of threading leaders where fabric is involved and by the use of inching devices. Indeed, every callender should be capable of being ‗inched‘ or run extremely slowly during the starting-up operations. Under these circumstances the braking is virtually instantaneous. A device used to facilitate joining of materials in order to permit continuous running of the calender is the festoon, which has already been mentioned in connection with running nips. Ancillary equipment causes 50 percent of the accidents occurring at calendars. This equipment consists of rollers or has rollers built into it because of the nature of the work. We must guard the nips between these rollers and the work in hand just as much as the calender – these are running nips. Many calenders form part of a large line of operation which present a potentially dangerous situation at starting or at a change in routine. It is imperative to consider carefully the sitting of controls. The starting control should be under the direct guidance of a supervisor who should follow a predetermined system of checking that all personnel are in positions of safety before commencing the operation. Communications or signals between members of the working gang should be established and understood by everyone joining the team.

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Industrial Safety (Running Nips)

FIGURE NO. 14.8 A TYPICAL ARRANGEMENT OF CALENDER AND AUXILIARY MACHINERY.

One of the lessons learned from accidents which have occurred at running nips is that one cannot rely upon the potential victim to operate a stopping device to save himself. When he realizes he is trapped he invariably tries to free himself before being pulled further into the nip. Therefore, safety devices should operate involuntarily.

SAFETY BY POSITION Another lesson learned from hard experience is that one cannot rely on the assumption that a nip is safe by position; nothing is safe by position if a person has to go near it, even if only occasionally and even if assess is difficult. One can only assume a state of ‗safety by position‘ if it is completely inaccessible.

CONCLUSION Many of the circumstances describe have a universal application and can be found in most factories. They constitute hazards not only to process workers but to maintenance workers who might become ensnared in circumstances with which they are not familiar. Running nip hazards need to be sought out and they are not always obvious. When they have been located there are two principles to be observed which serve as a useful guide to the effectiveness of guards.

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Industrial Safety (Running Nips)

The guard or system of guards should be such that it is impossible for an operative, during the legitimate and proper working of the machine under normal speed and power, to be able to reach with his hand or any part of his body or clothing the dangerous running nip. When the guards preventing access to the running nip are opened or moved away, so that such access is no longer completely denied, the machine must not be capable of moving under normal power or any other power that would cause other than relatively minor injury by trapping in the nip.

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Industrial Safety (Chemicals Safety)

INDUSTRIAL SAFETY (CHEMICALS SAFETY) PURPOSE The Chapter provides the guide line for the storage of chemicals according to their hazards and safety measures for the handling of the chemicals.

DEFINITIONS MSDS Abbreviation of material safety data sheet

FLAMMABLE Chemicals which have low ignition temperature (Flammables solvents have ―flash point‖ below 100°F).

CARCINOGENIC A substance which causes cancer.

PULMONARY Regarding the lungs.

STORAGE OF CHEMICALS Proper Storage is needed to minimize the hazards associated with accidentally mixing of incompatible chemicals. Chemicals storage, whether in the laboratory or ware house should be under the supervision of a qualified person, well aware of the hazards involved with the chemicals and know their proper handling. For the storage of chemicals, there should be a separate room equipped with the chemicals storage facilities.

C HEMICALS STORAGE

ROOM .

To ensure the safe storage of chemical substances, the storage room must be designed to cater for possible spills, fires and other mishaps. Recommendations for equipping a storage room for chemicals are as follows: The storage room should be equipped with shelves preferably of wooden (except for storage of oxidizers) material. The store area should be well ventilated with exhaust so as to check accumulation of chemicals vapours inside the store.

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Industrial Safety (Chemicals Safety)

Smoke detector should be installed in a chemical storage room. There should not be direct sunlight inside the storing facility. Proper cooling system should be installed for chemical store room. The storeroom floor should be equipped with a drainage system of sufficient capacity to provide fast and thorough flushing of spilled reagents. Personal safety equipment should be readily available inside storage facility.

GENERAL GUIDELINES

FOR THE STORAGE .

There are certain guidelines for the safe storage of chemicals The chemicals should be stored in a dry, adequately ventilated room with an effective cooling system. Chemicals should be protected from direct sunlight and intense heat. Chemicals should not be stored alphabetically but according to hazards. Store hazardous chemicals below the shoulder height of the shortest person working in laboratory. Temperature sensitive chemicals should be stored in freezers and refrigerators at appropriate storage temperature as specified by the chemical manufacturers. The freezers or refrigerators must be labeled ―NOT FOR STORAGE OF FOOD FOR HUMAN COSUMPTIONS‖. Select lower shelves or cabinets for heavy containers. All the chemical containers to be stored should be in good condition, properly capped and labeled. Empty containers should be disposed of properly. Be sure that container is empty. Following guidelines are provided for the safe storage of chemicals in accordance with their hazard classes.

STORAGE

OF

ACIDS (H2SO4, HNO3, HCL, HF

ETC)

Acids should not be stored in the vicinity of reactive metals e.g. Na, K, Mg etc. Segregate oxidizing acids (H2SO4, HNO3) from organic acids, flammable combustible materials.

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Industrial Safety (Chemicals Safety)

Segregate acids from chemicals which could generate toxic or flammable gasses upon contract such as Sodium cyanide, Iron sulfide, Calcium carbide etc. Acids should be stored away from bases.

STORAGE

OF

BASES (NAOH, KOH, NH4OH, N2H4 ETC)

Bases should be stored away from acids, metals explosives, organic per oxides and easily ignitable materials.

STORAGE

OF

SOLVENTS (FLAMMABLE

AND HALOGENATED )

These should be stored away from oxidizing acids and oxidizers. These should be kept away from any source of ignition, heat, sparks or open flashes.

STORAGE

OF

OXIDIZING

AGENTS

(H2O2, KMNO4 ETC)

Storage place should be cool and dry. These should be stored away from combustible and flammable materials. These should be stored away from reducing agents such as Zinc alkali metals and formic acid.

STORAGE

OF

CYANIDES (HGCN, KCN

ETC)

Store these chemicals away from acids and oxidizers.

STORAGE

OF

WATER

REACTIVE CHEMICALS

Store water reactive chemicals in a cool, dry place and away from any water source.

STORAGE

OF

LIGHT

SENSITIVE CHEMICALS

(KMNO4, NA2S2O3)

Light sensitive chemicals should be stored in amber bottles at a cool, dry and dark place.

STORAGE

OF

PEROXIDE

FORMING CHEMICALS

(MERGE

WITH

OXIDIZERS)

Peroxide forming chemicals should be stored in air tight container in a dark, cool and dry place. Containers should be labeled with receiving, opening and disposal dates.

STORAGE

OF

TOXIC

CHEMICALS

Store these chemicals according to their nature using appropriate security where ever necessary. Materials safety data sheets may also be consulted.

STORAGE

OF I NCOMPATIBLE

C HEMICALS .

The storage of incompatible chemicals closely may lead to severe accidents in the laboratories. The most serious of these is the storage of acids (especially oxidizing acids) with flammable solvents, contact of a concentrated oxidizing

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113

acid with a flammable solvent would likely result in a fire or explosion. This may also happen in the event of an earthquake. Table No. 1 will provide general guidelines of incompatible chemicals while Table No. 2 will show the some common chemicals and their incompatible compounds. Table No. 1

GENERAL INCOMPATIBILITY Acids ,

Acids

OF

C HEMICALS .

Acids,

Alkalis,

Poisons,

Poisons,

Water,

Organic,

Inorganic

Organic

Reactive

Solvents

Oxidizers inorganic

oxidizing

Organic

(Bases)

Acids, inorganic Acids oxidizing Acids, Organic Alkalis, (Bases) Oxidizers Poisons, Inorganic Poisons, Organic Water, Reactive Organic, Solvents

= Not compatible – do not store together Table No. 2

SPECIFIC INCOMPATIBLE C HEMICALS . Chemicals

Incompatible Compounds

Acetic Acid

Chromic acid, nitric acid, hydroxyl compounds, ethylene glycol, perchloric acid, per oxides, permanganates

Acetone

Concentrated nitric and sulfuric acid mixtures and strong bases

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114

Acetylene

Chlorine, bromine, copper, fluorine, silver, mercury

Alkali Metals

Water carbon tetrachloride or other chlorinated hydrocarbons, carbon dioxide, the halogens

Ammonia anhydrous

Mercury, chlorine, hydrofluoric acid

Ammonium nitrate

Acids, metal powders, flammable liquids, chlorates, nitrates, sulfur, finely divided organic or combustible materials

Aniline

Nitric acid, Hydrogen per oxide

Arsenic materials

Any reducing agent

Azides

Acids

Bromine

Same as chlorine

Calcium Oxide

Water

Carbon (activated )

Calcium hypochlorite, all oxidizing agents

Carbon tetrachloride

Sodium

Chlorates

Ammonium salts, acids, metal powders, sulfur, finely divided organic or combustible materials

calcium

hypochlorite,

iodine,

Chromic acid and Acetic acid, naphthalene, camphor, glycerol, Chromium tri oxide turpentine, alcohol, flammable liquids in general

bromine,

glycerin,

Chlorine

Ammonia, acetylene, butadiene, butane, methane, propane (or other petroleum gases),hydrogen, sodium carbide, turpentine, finely divided metals

Chlorine Dioxide

Ammonia methane, phosphine, hydrogen sulfide

Copper

Acetylene, hydrogen peroxide

Cyanides

Acids

Flammable Liquids

Ammonium nitrates, chromic acid, hydrogen per oxide, nitric acid, sodium peroxide, halogens

Hydrocarbons

Fluorine, chlorine, bromine, chromic acid, sodium peroxide

Hydrofluoric Acid

Ammonia, aqueous or anhydrous

Hydrogen peroxide

Copper, Chromium, iron, most metals or their salts, alcohols, acetone, organic materials, aniline, nitro methane, flammable liquids

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115

Hydrogen Sulfide

Fuming nitric acid, other acids, oxidizing gases, acetylene, ammonia (aqueous or anhydrous ), hydrogen

Hyper chlorite

Acids, activated carbon

Iodine

Acetylene, ammonia, (aqueous or anhydrous), hydrogen

Mercury

Acetylene, fulminic acid ammonia

Nitrates

Sulfuric acid

Nitric (concentrated )

acid Acetic acid, aniline, chromic acid, hydrocyanic acid, hydrogen sulfide, flammable liquids, flammable gases, copper, brass, any heavy metals

Nitrites

Acids

Nitro paraffins

Inorganic brass

Oxalic Acid

Silver, mercury

Oxygen

Oils grease, hydrogen, flammable liquids, solids or gases

Perchloric Acid

Acetic anhydride, bismuth and its alloys, alcohol, paper, wood, grease and oils

Per oxides, organic

Acids (organic or mineral), avoid friction, store cold

Phosphorus (white)

Air, oxygen, alkalis, reducing agents

Potassium

Carbon tetrachloride, reducing agents

Potassium chlorate Sulfuric and other acids and per chlorate Potassium Permanganate

Glycerin, ethylene glycol, benzaldehyde, sulfuric acid

Selenides

Reducing agents

Silver

Acetylene, oxalic acid, tartaric acid, ammonium compounds, fulminic acid

Sodium

Carbon tetra chloride, carbon dioxide, water

Sodium nitrite

Ammonium nitrate and other ammonium salts

Sodium Peroxide

Ethyl or methyl alcohol, glacial acetic acid, acetic anhydride, benzaldehyde, carbon disulfide, glycerin, ethylene glycol, ethyl acetate, furfural

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116

Sulfides

Acids

Sulfuric Acid

Potassium chlorite, potassium per chlorate, potassium permanganate (or compounds with similar light metals, such as sodium, lithium, etc.)

Tellurides

Reducing agents

Industrial Safety (Chemicals Safety)

HANDLING OF CHEMICALS The chemical laboratory is a potentially dangerous place; however, if proper precautions are taken and safe procedures followed, the risk is minimal. Regard all chemicals as hazardous until you know otherwise.

HEALTH

HAZARDS OF CHEMICALS :

Chemicals can enter the body by three routes. Via skin absorption from the liquid, solid or even gaseous state. Via the respiratory tract, due to inhalation. Via the gastrointestinal tract, following accidental ingestion. Chemicals can produce a wide range of damaging effects on tissue and organs. In the laboratory the greatest risk is of skin damage, followed by skin absorption and inhalation of chemicals .some chemicals, such as strong acids and alkalis ( e g Chromic acid, Sulfuric acid, Nitric acid, Sodium hydroxide) produce damage within a very short period of contact, others require prolonged, repeated contact before an effect is seen (e g liver damage and cancer by inhaled carbon tetrachloride, leukemia by inhaled benzene, allergic contact dermatitis from some chemicals).

SAFETY MEASURES If contact occurs with the skin, wash the affected area thoroughly with soap (or detergent) and water. Rubber gloves are available and are to be worn when handling radioactive, toxic or corrosive chemicals and when washing up contaminated glassware. Do not inhale fumes and vapors of chemicals. If a noxious gas, vapor dust or mist is being used or produced, work in the fume hood. An efficient gas trap should also be used. Never taste or smell chemicals. Do not use mouth to fill a pipette, use a pipette filler.

FIRE

HAZARD OF

ORGANIC

SOLVENTS

Most organic solvents are flammable or toxic and should be treated as all other flammable and toxic chemical substances. The vapors of many common organic solvents can cause fire hazard even in the absence of a naked flame. e.g. Carbon disulfide, Diethyl ether, Dibutyl ether, Dioxan, Light petroleum, Heptane, Cyclohexane and many others. The vapors of these

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Industrial Safety (Chemicals Safety)

organic solvents can be ignited by a meager source of heat e.g hot electric mantle, an electric light bulb, a room heater not visibly glowing, overheated electrical connections etc.

HANDLING

OF ORGANIC SOLVENTS

Flammable solvents must be stored in a laboratory in approved fire resistance storage cabinets, sited as far away from sources of ignition as possible. Reduce to the absolute minimum quantities of flammable and toxic solvents used in chemical operations or held in temporary storage. Flammable solvents should be stored away from doorways, passages or escape routes. When use of flammable solvents is intended, all potential sources of ignition must be kept away from the working area. With carbon disulfide, ethers and petroleum, the vigilance must be extreme. Ethers must not be distilled unless chemical test show the absence of explosive peroxide. Highly toxic and carcinogenic solvents should be used in fume hoods only, and any spillages on skin and clothes washed off immediately. Hot plate should be used preferably instead of gas burners. If gas is to be used, before lighting a burner check that there is no flammable vapour (ether, petroleum etc) nearby. Make sure you know where the fire extinguishers and fire blankets are and how to use them.

HANDLING OF SOME COMMON COMPOUNDS SULFURIC ACID Never add water to the acid Always add acid to the water

DESCRIPTION It has following properties: It is oily liquid. Colorless. Odorless.

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Industrial Safety (Chemicals Safety)

Sink and mixes violently with water. Irritating mist is produced.

EMERGENCY RESPONSE Avoid contact with liquid. Keep people away.

SAFELY PRECAUTIONS /PERSONAL PROTECTION

DURING

USE

Following personal protective equipment must be used: Wear goggles for eye protection Self-contained breathing apparatus for respiratory protection Rubber over clothing including gloves & safety shoes for body protection

FIRE HAZARD It is non flammable. May cause fire on contact with combustibles. Flammable gas may be produce on contact with metal. Extinguish fire with dry powder or CO2. Do not use water on adjacent fires.

HEALTH HAZARD Irritating to eyes, nose and throat Eye contact: Hold eyelids open, and flush with plenty of water for 15 minutes If inhaled: Will cause coughing, difficult breathing or loss of consciousness Move to fresh air, if breathing has stopped give artificial respiration, if breathing is difficult give oxygen. If swallowed: If victim is conscious, have victim drink water or milk. Do not induce vomiting. Contact with skin cause burns.

RESPONSE

TO

DISCHARGE Issue warning because it is corrosive Restrict access Disperse and flush with care

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Industrial Safety (Chemicals Safety)

Cover spill with sodium bicarbonate or soda-ash-slacked mixture Mix and add water to form slurry. Scoop up slurry Then wash site with soda ash solution

NITRIC ACID DESCRIPTION It has following properties: It is watery liquid Colorless, yellow-red or light-brown Acrid, suffocating odder Sinks and mixes with water Harmful vapor is produced

EMERGENCY RESPONSE Avoid contact with liquid and vapor

SAFELY PRECAUTIONS /PERSONAL PROTECTION DURING USE Following personal protective equipment shall be used: Wear rubber gloves Chemical protective rubber suit with air respirator with full face mask Safety boots and chemical goggles Provision of safety shower and eye bath

FIRE HAZARD Not combustible/not flammable May cause fire on contact with combustibles Flammable gas may be formed on contact with metals Poisonous gases are produced when heated Cool exposed containers with water Large quantities of water in spray or fog form should be used for extinguishing fire

HEALTH HAZARD Irritating to eyes, nose and throat

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Industrial Safety (Chemicals Safety)

Eye Contact: Hold eyelids open and flush with plenty of water for 15 minutes If inhaled: Will cause coughing, difficult breathing or loss of consciousness. Move to fresh air, if breathing has stopped give artificial respiration, if breathing is difficult give oxygen If swallowed and victim is conscious, have victim drink water or milk. Do not Induce vomiting Contact with skin cause burns

RESPONSE

TO

DISCHARGE

Issue warning because it is corrosive Restrict access Disperse and flush with care Cover spill with sodium bicarbonate or soda-ash-slacked mixture Mix and add water to form a slurry. Scoop up slurry Then wash site with soda ash solution

SODIUM HYDROXIDE NAOH (CAUSTIC SODA) DESCRIPTION It has following properties: It is in the form of Solid flakes or pellets White in color Odorless Sinks and mixes with water

EMERGENCY RESPONSE Avoid contact with solid and dust. Keep people away.

SAFELY PRECAUTIONS /PERSONAL PROTECTION DURING USE Following personal protective equipment shall be used: Wear chemical safety goggles/splash proof goggles for eye protection Full face shield with filter or dust type respirator for respiratory protection Rubber boots and rubber gloves for foot and hand protection

FIRE HAZARD

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Industrial Safety (Chemicals Safety)

Non combustible/non flammable solid, when come in contact with water may generate sufficient heat to ignite combustible materials May cause fire on contact with combustibles Flammable gas may be produced on contact with metals Surrounding fires may be extinguished with appropriate fire extinguishing agent Decomposition produces toxic fumes of sodium oxide

HEALTH HAZARD It is corrosive and hazardous strong corrosive action on contacted tissues after exposure Inhalation: Inhalation of dust may cause damage to upper respiratory tract and lung. Remove victim from exposure, support respiration and call doctor Ingestion: If ingested, causes severe damage to mucous membrane, severe scare formation on perforation may occur. Have victim drink water or milk followed by dilute fruit juices. Do not induce vomiting. Skin Contact: Wash immediately with large quantities of water under safety shower. While removing clothing, continue washing until medical help arrives. Eye Contact: Produces severe damage, wash immediately with copious amount of water for at least 15 minutes. Call doctor.

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Industrial Safety (Chemicals Safety)

AMMONIA DESCRIPTION: It has following properties; It is liquefied compressed gas It is colorless Pungent ammonia odor It floats and boils on water It is poisonous Visible vapor cloud is produced.

EMERGENCY RESPONSE Avoid contact with liquid and vapor. Keep people away.

SAFELY PRECAUTIONS /PERSONAL PROTECTION

DURING

USE

Following personal protective equipment shall be used: Gas tight chemical goggles for eye protection Self contained breathing apparatus Chemical cartridge respirator with full-face mask and ammonia cartridges for respiratory protection Rubber boots, rubber gloves for foot and hand protection Provision of emergency shower and eye bath. Fire Hazard It is flammable gas Stop flow of gas or liquid if possible Let fire burn Do not put water on liquid ammonia Use water to cool exposed containers and reduce vapor concentrations. Water spray is extremely effective in absorbing ammonia gas and should be used around leaks of gas only. Surrounding fire should be extinguished with appropriate agents. While burning irritating fumes are produced

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Industrial Safety (Chemicals Safety)

While burning in sealed containers, it may rupture and explode

HEALTH HAZARD VAPOR Poisonous if inhaled, irritating to eyes, nose and throat May cause lung edema Move to fresh air If in eyes hold eyelids open and flush with plenty of water under eye bath for 15 minutes If inhaled and breathing has stopped, give artificial respiration to the victim. If breathing is difficult give oxygen to the victim.

LIQUID It will burn skin and eyes If swallowed, it is harmful Will cause frostbite on contact with skin i.e. freezes the tissues and then produce a caustic burn. Remove contaminated clothing and shoes. Flush affected area with plenty of water If inhaled and breathing has stopped, give artificial respiration to the victim. If breathing is difficult give oxygen to the victim If swallowed and victim is conscious, have victim drink water or milk Do not rub affected area. 2500-PPM concentration of ammonia is air may be fatal within 30 minutes. 500-PPM concentration in air can cause immediate death from spasm, inflammation hour or edema of larynx.

RESPONSE

TO

DISCHARGE

Stop discharge if possible Stay upwind and use water spray to knock down vapor Isolate in all direction up to 500 feet and Remove discharged material Use water spray around leakage for absorption of ammonia vapor Do not put water in liquid ammonia

HYDROCHLORIC ACID/HYDROGEN CHLORIDE DESCRIPTION It has following properties: Watery liquid or gas

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Industrial Safety (Chemicals Safety)

Colorless Sharp irritating odor Sinks and mixes with water Irritating vapor and produced Highly corrosive to most metals with emission of hydrogen gas. Corrosive fumes are produced on contact with air

EMERGENCY RESPONSE Avoid contact with liquid and vapor Keep people away

SAFELY PRECAUTIONS /PERSONAL PROTECTION DURING USE Following personal protective equipment shall be used: Chemical protective clothing, apron, coat or overall for body protection Full face mask with industrial canister type gas mask for respiratory protection Rubber or rubber coated gloves for hand protection Shoes for foot protection Goggles for eye protection

FIRE HAZARD It is non flammable/non-combustible Flammable gas may be produced on contact with metals Toxic and irritating vapors are produced when heated Appropriate agents should be used on the surrounding fire Water spray should be used to keep cool the container

HEALTH HAZARD Inhalation of vapor and fumes causes coughing and checking sensation and irritation of nose and lungs Vapor is irritating such that personnel will not tolerate moderate to high vapor concentration Vapor and fume will burn skin and eyes

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Industrial Safety (Chemicals Safety)

Liquid or solid contact with skin or eyes will cause fairly serve eye and skin irritation and after few minutes, pain and burn of skin and eyes occurs. Rapid evaporation of liquid may cause frostbite Eye Contact: Immediately flush skin with plenty of water while removing contaminated clothing. Soap can be used during washing and continue washing for 15 minute. Medical aid should be provided If Ingested: Have person drink water or milk. Do not induce vomiting If Inhaled: Remove person to fresh air, keep him warm and quiet. Artificial breathing should be started if breathing has stopped

RESPONSE

TO

DISCHARGE

It is corrosive, restrict access Stop discharge if possible Dispense and flush with water Stay up wind and use water spray to ―knock down‖ vapor Isolate and remove discharged material Isolate in all the directions-500 feet Protect people down wind Apply neutralizing agents like powdered lime stone, slaked lime, soda ash or sodium bicarbonate

POTASSIUM CHROMATE DESCRIPTION It has following properties: Solid, bright yellow Odorless Sinks and mixes with water

EMERGENCY RESPONSE Keep people away Avoid contact with solid and dust

SAFELY PRECAUTIONS /PERSONAL PROTECTION DURING USE Following personal protective equipment shall be used: Filter type respirator with full face mask for respiratory protection with high efficiency particulate filter .

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Industrial Safety (Chemicals Safety)

Close fitting safety goggles for eye protection Rubber boots Apron Safety hat

FIRE HAZARD Not flammable but increase the decomposes oxygen is produced

intensity

of

fire

because

when

May cause fire on contact with combustibles Use plenty of water/blood to discharge area Exposed container should be closed with water

HEALTH HAZARD Dust is irritating to eyes, nose and throat If inhaled will cause coughing a difficult breathing If in eyes, hold eyelids open and flush with plenty of water If inhaled, and breathing is difficult given oxygen, if breathing has stopped give artificial respiration Solid is poisonous if swallowed, it will cause nausea, vomiting or loss of conscious. It is irritating to eyes and skins. Flush eye with plenty of water If swallowed and victim is conscious, have victim drink water or milk and induce vomiting If swallowed and victim is unconscious, do nothing except keep him warm, call doctor

RESPONSE

TO

DISCHARGE

Dispense and flush

GENERAL SAFETY RULES Following safety rules are strictly enforced in chemistry laboratories/ industries.

EYE

PROTECTION

Safety goggles or safety glasses which provide adequate protection from chemical splashing are to be worn in laboratories

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Industrial Safety (Chemicals Safety)

whenever dangerous and irritating materials such as acids are handled. Contact lenses provide no protection and are an additional hazard in the laboratory. Contact lenses must not be worn in the laboratory. This is standard practice in all chemical laboratories. If chemicals are splashed directly into the eye, the presence of a contact lens greatly exacerbates the problem. Even if you are not using chemicals directly or are wearing safety goggles over the contacts, contact lenses are not good in the laboratory. Solvent vapors can permeate the lenses and be held in close contact to the cornea, causing long term scarring. You should have a pair of normal prescription glasses for use in the laboratory. Safety goggles or safety glasses which provide adequate protection from chemical splashing are to be worn in addition to conventional glasses. Conventional glasses do not provide adequate protection against splashing. A shield giving complete face protection should be used for dangerous analytical work (acid & caustic tanker‘s sample analysis). Use a laboratory coat, made from cotton or cotton/polyester material. Lab coat must be worn when handling corrosive, toxic, or flammable materials Gloves should be worn when necessary especially when handling radioactive, corrosive and highly toxic materials. Safety shoes must be used Long hair must be safely confined Hair is flammable and is to be tied or pinned back or confined in a hair net. Solutions must not be pipetted by mouth rubber bulb pipette filler should be used for all solutions. No food or drink is to be consumed in the laboratory. Smoking is not allowed in any part of chemistry laboratories area. Know where the following safety equipment is located and how to use it: o

Fire extinguishers

o

Fire blankets

o

Safety showers

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Industrial Safety (Chemicals Safety)

o

Eye wash stations

o

First aid boxes

o

Familiarize yourself with the evacuation procedure.

If you see a colleague doing some thing dangerous, point it out to him or her. Know how to clean up spills of the chemicals that are used Wash your hands after handling chemicals and before leaving the lab. Transport flammable and toxic solvents carefully in stout glassware and in quantities comfortably within your control. 2.5L and 4L quantities should be carried in special carriers. Highly toxic and carcinogenic solvents should be used in fume hoods only, and any spillages on skin and clothes washed off immediately. Make sure you know where the fire extinguishers and fire blankets are and how to use them. Flammable liquids should be stored only in specially modified refrigerators. Ordinary domestic type ―fridges‖should not be located in areas where flammable liquids may be used, as ignition and fire may occur from the normal sparking of ordinary switches and devices in such units.

FIRST

AID IN ACCIDENTS INVOLVING CHEMICALS .

For accidents involving chemicals, carry out the first aid procedure recommended for the product involved as prescribe on the material safety data sheet (MSDS). Also supply information about the chemicals involved to medical personnel. The instruction on the MSDS should be communicated to the doctor and the data sheet be taken with the patient.

EXTENSIVE

BURNS

Wash off any residual chemical. Cover injuries with a sterile gauze, towel or sheet. Leave clothing where it is. Leave neck and head uncovered. Do not apply any oils creams or jelly. Then take the patient to the hospital for further treatment.

MINOR

BURNS

Cool the burnt area under running cold tap water. Get medical help at PAEC hospital Chashma for treatment.

EYE

INJURIES

If chemical splash in the eye of a worker, he should immediately flush the eyes with water for about twenty minutes from the nearest safety shower /sprinkler.

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Industrial Safety (Chemicals Safety)

In case of splinters of glass or metal in the eye, cover both eyes and get medical help as soon as possible

C HEMICAL

SPILLAGE ON SKIN OR CLOTHING :

When some chemical spill on skin and cloth, wash off the chemical immediately with sufficient amount of cold tap water for at least fifteen minutes. Organic material can be absorb through the skin and in these cases follow the cold water washing by a thorough washing with warm water and soap. Contaminated clothing should be removed as soon as possible and thoroughly wash. Seek medical advice.

130

(SAMPLE PAPER)

(SAMPLE PAPER) 1. Major Injury leads to ____ or more days of work lost a. 2 b. 3 c. 4 d. 5 2. The surface color of Ammonia Cylinder is a. Yellow b. Black c. Dark Green d. White 3. Store Oxygen at least _____ ft from flammables and combustibles: a. 10 b. 20 c. 30 d. 40 4. dB is a unit for measurement of _____ a. Height b. Fire intensity c. Noise d. Acidity 5. Gas filter Type-E is mainly used against inhalation danger of: a. SO2 b. HNO3 c. Organic gases d. Ammonia

131

(SAMPLE PAPER)

6. Filters that are not factory sealed must be used within: a. 3 months b. 6 months c. 1 years d. 3 years 7. smothering effect extinguish the fire by: a. Reducing Oxygen b. Reducing CO2 c. Increasing CO2 d. Increasing air flow 8. Fires due to Flammable Liquid are classified as: a. Class-A fire b. Class-B fire c. Class-C fire d. Class-D fire 9. __mili Ampere (mA) is accepted as maximum harmless current a. 1 b. 5 c. 10 d. 20 10.Never add ___ to _____ a. Acid to Water b. Water to Acid c. Alkali to Water d. HCl to NaOH

132

References

REFERENCES 1.

DOE hand Book on Electrical safety

2.

Industrial Safety Hand book (2nd ed.) by William Houndley

3.

Industrial Fire Protection Handbook by R. Craig Schroll

4.

CHASNUPP Procedure TP-CY-11 (Storage & handling of chemicals) Rev-0

FURTHER STUDY 1.

Workplace Health and Safety Source Book, Omnigraphics,1999 by Henderson, Helene

2.

Accident / Incident Prevention Techniques, Routledge, 2001 by Reese, Charles D.D.

3.

Occupational Safety Management and Engineering, Eth ed. By, Hammer, Willie

4.

―Safety First‖ by Aldrich, MaMark, John Hopkins University Press

133