Fire Technology and Arson Investigation

Page 1 of 26/ The University of Manila/ College of Criminology

THE UNIVERSITY OF MANILA College of Criminology SUBJECT-3  CRIME !ETECTION AN! INVESTI"ATION FIRE TECHNOLO"Y AN! ARSON INVESTI"ATION Te#$nology %n& #%'(e( of fire) Fire Tri%ngle T$eory The graphical representation of the three elements of fire, namely: Oxygen, Heat, and Fuel. Each side is just as important as either of the other two sides. There cannot be fire without all the three parts present in eual proportion. !sing the same theory, there are three ways to extinguish fire:

1. Remove the fuel 2. Cut-o the oxygen supply "* #educe the temperature $cooling% Elemen+( of Fire &. He%+ ' He%+ ' a form of energy generated by the transmission of some other form of energy, as in combustion or  burning.

Heat Sources: 1. Open ame !. Hot surfaces 2. "lectr#cal c#rcu#t $. %r#ct#on %r#ct#on ". (par)s

*. +ll sources of ignition

. O,ygen ' O,ygen ' a colorless, odorless gas and one of the compositions of air which is approximately &- by olume.

Oxygen Sources:   1. 21 ' of normal oxygen 2. )* ' of n#trogen ". & - of other gases

Oxygen Re&u#rements 1. 12 ' - no (re 2. 1! ' - ash po#nt ". & - ' fire point

". F'el ' F'el ' any substance which reacts chemically with oxygen and produces flames. The most important element of fire. F'el So'r#e(

1. Solid - molecules are closely pac+e, together 2. Liquid - molecules are loosely pac+e, ". "%( ' "%( ' molecules are free to moed Fire Te+r%$e&ron The fire, triangle theory describes the three elements, of a fire as shown in Figure &.&. +nother explanation of the reuirement of combustion uses a four'sided figure called tetrahedron as shown in Figure &.. /oth theories are used to explain what causes fire. The fourth element of the tetrahedron explanation is )nown as chemical reactiity, or chemical reaction. For 0ombustion to occur, four elements a re necessary:

1. Oxygen ox#,##ng agent/ 2. %uel 0. Heat 1. (elf ' sustaining chemical reaction. These elements can be graphically described as the fire tetrahedron. Each element of the tetrahedron must be in place for  combustio combustion n to occur. occur. This This theory theory is extremely extremely important important to students students of fire suppression, suppression, preention preention,, and inestig inestigation ation.. #emoing any one of the f our elements combustion will not occur. 2f ignition has already started, the fire is extinguished, if  one of the elements is remoed from the reaction.

Page 2 of 26/ The University of Manila/ College of Criminology Com.onen+(/Elemen+( of +$e Fire Te+r%$e&ron &. O,ygen 0O,i&i1ing Agen+2 Oxidi3ing agents are those materials that yield oxygen or other oxidi3ing gases during the process of a chemical reaction. . F'el 0Re&'#ing Agen+2 Fuel is the material or substance being burned in the combustion process. ". He%+ 0Tem.er%+'re2 Heat is the energy component of the fire tetrahedron. 4hen heat comes in contact with a fuel, the energy supports the combustion process. Com'(+ion Re%#+ion(/4ro#e((

 Causes pyrolys#s or vapor#at#on of sol#, an, l#&u#, fuels an, the pro,uct#on of #gn#tale vapors or gases3  Prov#,es the energy necessary for #gn#t#on3 5 0auses the continuous production production and ignition of fuel apors or gases to continue continue the combustion reaction. Ty.e( of Energy 0Common So'r#e( of He%+2 &. C$emi#%l &. C$emi#%l Energy 2t is the most common source of heat in combustion reactions. 4hen any combustibles are in contact with oxygen oxidation occurs. The reaction of this process results in the production of heat. Examples: Heat generated from a burning match, (elf'heating $spontaneous heating%. . Ele#+ri#%l Energy Electrical energy can generate temperatures high enough to ignite any combustible materials near the heated area. ". N'#le%r Energy 6uclear heat energy is generated when atoms either split apart $fission% or combine $fusion%. Examples:

a. %#ss#on heats heats 4ater to ,r#ve steam tur#nes an,

pro,uce electr#c#ty. electr#c#ty.

b. The solar energy is a product of a fusion reaction $a form of nuclear energy%. 1. Me#$%ni#%l Energy  +n energy created by friction and compression. compression.

 Heat of Frition - #s the movement of t4o surfaces aga#nst each other. 5h#s movement pro,uce, spar+s e#ng generate,. 5 He%+ of Com.re((ion ' Com.re((ion ' heat is generated when a gas is compressed in a container or cylinder. Self-S'(+%ine& C$emi#%l Re%#+ion 0+$e fo'r+$ elemen+2 0ombustion is a complex reaction that it reuires a fuel $gaseous or apor state%, an oxidi3er, and heat to combine in a ery specific way. Once flaming starts, it can only continue when enough heat or energy is produced to cause the continued chain reaction. 0hain reaction is a series of eents that occur in seuence with the results of each indiidual reaction being added to the rest. Com'(+ion Fire and combustion are terms that are often used interchangeably. Technically spea)ing, fire is a form of combustion. 0ombustion is a self'sustaining chemical reaction producing energy or products that cause more reactions of the same )ind. 0ombustion is an exothermic reaction. Fire is a rapid, self'sustaining oxidi3ation process accompanied by the release of heat and light of different intensities. intensities. The time it ta)es a reaction to occur determines the type of reaction that is obsered. 4ro&'#+( of Com'(+ion Fo'r 052 C%+egorie( of .ro&'#+( of #om'(+ion &. Fire &. Fire g%(e(

Page ! of 26/ The University of Manila/ College of Criminology 7 are those that remain when other products of combustion cool to normal temperature. 0ommon combustibles contain carbon, which forms carbon dioxide and carbon monoxide when burned. Other fire gases include hydrogen sulfide, sulfur  dioxide, ammonia, hydrogen cyanide, nitrous and nitric oxide, phosgene, and hydrogen chloride. The records of fatal fires show that more people died from inhaling these super'heated and toxic fire gases than from any other cause. The complete combustion of fuels containing carbon will produce 0O , but seldom will there be enough oxygen for  complete combustion. 4hen only part of the carbon is oxidi3ed, carbon monoxide is formed. 4hile carbon monoxide is not the most toxic fire gas, it causes mote deaths than any other because robs the body of oxygen Ty.e( of 4oi(ono'( "%(e( Hy&rogen S'lfi&e 0H 6S2 Hy&rogen Cy%ni&e 0HCN2 Hy&rogen C$lori&e 0HCl2 . Fl%me 2t is the luminous body of a burning gas which gets hotter and less luminous when mixed with more oxygen. Flame fades when carbon burns completely, so flame is considered a product of incomplete combustion. 2t is the manifestation of fire when the fire is in its gas'phased combustion. N%+'re of Fire Een the most flammable materials $capable of being easily ignited% do not actually burn. The apor gien off by a material is the part that burns. 4hen a piece of wood is ignited, the fire is not from the burning wood, rather, from the apors that are gien off by the wood. The heat causes the substance in the wood to apori3e. The heated apors mix uic)ly with oxygen in the air and fire results. This process is )nown as 8yrolysis. 4yroly(i( 2t refers to the chemical process whereby fire consumes the most solid part of the fuel. 2t is the thermal decomposition of a solid fuel through the action of heat.

 5he process of Pyrolys#s #nvolves the follo4#ng: 1. 5he fuel #s heate, unt#l #ts temperature reaches #ts (re po#nt3 2. 6ecompos#t#on ta+es place 7 mo#sture #n the fuel #s converte, to vapor3 0. 6ecompos#t#on pro,uces comust#le vapors that r#se to the surface of the fuel. 5hese comust#le vapors are techn#cally terme, as free ra,#cals3 1. Free'radicals undergo combustion if proper amount of oxygen is present.

 5he most common type of free-ra,#cals - comust#le vapors/: 1. Hy,rogen gas 2. Caron monox#,e 0. Caron ,#ox#,e 1. 6itrogen

8ost (res 4#ll #nvolve #ncomplete comust#on9 pro,uc#ng CO an, caron part#cles along 4#th heat9 4ater vapor9 an, CO 2.  + fire inoling material other than hydrocarbons and oxygen will produce combustion products composed of the atoms and molecules forming the material together with the oxidi3er used for the support of the combustion. This is the reason a poisonous fuel may gie off poisonous fumes and smo)e.

". He%+  + form of energy measured in degree of temperature, it is the product of combustion that spread the fire. 2t causes burns and other injuries such as dehydration, heat exhaustion, and respiratory tract injuries. Heat, oxygen depletion, and carbon monoxide formation are the primary ha3ards in fires.

Page " of 26/ The University of Manila/ College of Criminology 1. Smo7e 2t is the isible product of incomplete combustion, usually a mixture of oxygen nitrogen, carbon dioxide, carbon monoxide, finely diided particles of soot and carbon, and miscellaneous assortment of product released from the burning material. 4ro.er+ie( of Fire A* 4$y(i#%l 4ro.er+ie( &. S.e#ifi# gr%8i+y ' the ratio of the weight of a solid or substance to the weight of an eual olume of water  . V%.or &en(i+y ' the weight of a olume of pure gas compared to the weight of a olume of dry air at the same temperature and pressure ". V%.or .re(('re ' the force exerted by the molecules on the surface of the liuid at euilibrium. 1. Tem.er%+'re ' the measure of thermal degree of the agitation of molecules of a gien substance9 the measure of the molecular actiity within a substance. . Boiling .oin+ ' the constant temperature at which the apor pressure of the liuid is eual to the atmospheric pressure. *. Igni+ion +em.er%+'re or 7in&ling +em.er%+'re ' the minimum temperature to which the substance in the air must be heated in order to initiate or cause self'contained combustion without the addition of heat from outside sources. ;. Fire .oin+ ' the temperature at which the material will gie off ample apors to )eep burning. There is usually about 'to &. Fl%($.oin+ ' the temperature at which a material is not hot e nough to )eep burning, but still gies off enough apors to cause a flame to ?flash@ across the surface. The term ?flashpoint@ is used to e xpress the condition of a fuel apori3ing, whether or not it is apori3ing fast enough to )eep burning. B* C$emi#%l 4ro.er+ie( &. En&o+$ermi# re%#+ion ' are changes whereby energy $heat% is absorbed or is added before the reaction ta)es place. . E,o+$ermi# re%#+ion ' reactions or changes that release or gie off energy $heat% thus they produce substances with less energy than the reactants. ". O,i&%+ion ' a chemical change in which combustible material $fuel% and an oxidi3ing agent react. 1. Com'(+ion/fl%me ' the manifestation of fire when the fire is in its gas'phased combustion. + matter that is produced by fire. V%.or !en(i+y The term used to explain the weight of apors is ?apor density@. 2n order to measure the weight of these apors we usually compare them to air, which is considered to hae a apor density of &.or #nterest #n the (re.  #nterv#e4 an, #nterrogat#ons of person;s 4ho ,#scovere, the (re9 the person 4ho act#vate, the (re alarm9 (remen9 an, eye4#tnesses. 5 sureillance Tell T%le Sign( These signs maybe obious that the first fireman at the fire scene will suspect arson: &. B'rne& B'il&ing the type of building may indicate a set fire under certain circumstances. + fire of considerable si3e at the time the first apparatus arries at the scene is suspicious if a modern concrete or semi'concrete building is inoled. . Se.%r%+e fire( when two or more fire b rea)s out within a building, the building is certainly suspicious. ". Color of (mo7e

Page 2' of 26/ The University of Manila/ College of Criminology some fire burn with little or no smo)e but there are exceptions to this. The obseration of the smo)e must be made at the start of the fire since once the fire has consumed a major proportion9 the alue of the smo)e is lost, because the smo)e will not indicate the material used by the arsonist.

 hen 4h#te smo+e appears efore the 4ater from the (re hose comes #n contact 4#th the (re9 #t #n,#cates hum#, mater#als urn#ng. "xamples: hay9 vegetales9 phosphorous 4#th garl#c o,or.  @#t#ng smo+e #n,#cates lac+ of a#r ut #f accompan#e, large ames #t #n,#cates petroleum pro,ucts an, ruer. 5 #eddish'brown smo)e indicates nitrocellulose. (2, H, (O1, H6O ", H0l. In&i#%+ion of Color of Smo7e %n& Fire Color of Smo7e /lac) smo)e with deep red flame

Heay brown with bright red flame 4hite smo)e with bright flame /lac) smo)e with red and blue green flame 8urple'iolet flame reenish'yellow flame /right reddish'yellow flame 1. Smo7e M%r7(

M%+eri%l/S'(+%n#e 8etroleum products such as tar, rubber, plastics, etc. 6itrogen products Cagnesium products   +sphalt 8otassium products 0hloride and manganese products 0alcium products

an experienced inestigator will determine the olume of smo)e inoled at a fire and the character as residue deposited on walls or elsewhere. (mo)e mar)s hae often been of assistance in determining the possibility of a fire haing more than one place of origin. . Color of Fl%me

 5he color of the ame #s a goo, #n,#cator of the #ntens#ty of the (re9 #t #s an #mportant factor #n ,eterm#n#ng #ncen,#ar#sm.  A re,,#sh glo4 #n,#cates heat of aout $DDD EC.9 a real l#ght re, aout 1DDD EC  Re, ames #n,#cate presence of petroleum pro,ucts 5 /lue flame indicates use of alcohol as accelerant *. Si1e of fire The si3e of fire is important when correlated with the type of alarm, the time receied and the time of arrial of the first responder at the fire scene. Fire ma)es what might be termed a normal progress. (uch progress can be estimated after  an examination of the material burned in the building, and the normal entilation offered to the fire. The time element and the degree of headway much by the flames became important factors to determine possible incendiarism. ;. !ire#+ion of Tr%8el 4hile it is admitted that no two fires burn in identical fashion, yet it can be shown that the fire ma)es normal progress through arious types of building. 0onsidering the type of construction, the building materials, combustibility of contents, channel of entilation and circumstances surrounding the sending of alarm, an experienced inestigator can determine whether a fire has spread abnormally fast. >. In+en(i+y The degree of heat gien off by a fire and the color of its flame often times indicate that some accelerant has been added to the material normally present in a building and the inestigator must loo) further for more eidence used of such accelerant. ifficulty in extinguishing the fire is often a lead to suspect presence of such fluid or liuid as gasoline and )erosene. G. O&or The odor of gasoline, alcohol, )erosene and other flammable liuids which are often used as an accelerant is a characteristics, and often times an arsonists is trapped because of this tell tale sign. Cost of fire'setters are inclined to use substances which will ma)e the bla3e certain and at the same time burn up any eidence of their crime. &