GUIDE TO GOOD PRACTICE
Internal cleanliness of ventilation systems (TR19) Second Edition | October 2013
Specialist Groups Building & Engineering Services Association Esca House, 34 Palace Court, London W2 4JG T 020 7313 4937 www.b-es.org
Acknowledgement B&ES records its appreciation and thanks to the many persons and organisations who have freely given information on various aspects of this work, in particular to the following members of the Ventilation Hygiene Group Branch and Ductwork Technical Sub-Committee, who contributed unstintingly of their knowledge and experience to this later edition: Craig Booth
Jim Murray
Paul Downing
Gary Nicholls
Alan Gregory
Richard Norman
Gareth Keller
Nick Tregaskes
Steve Lorriman
Peter Reid
Special thanks are offered to J Bridges for his assistance in the development of the Deposit Thickness Test, and to T Mulhall of the HSE.
ISBN 0 903783 35 5
Publishing history: First published as DW/TM2 (1991) and TR/17 (1998) Second Edition (2002) and TR/19 (2005 and 2013)
Building & Engineering Services Association Esca House 34 Palace Court London W2 4JG T: 020 7313 4900
[email protected] www.b-es.org
GUIDE TO GOOD PRACTICE
Internal cleanliness of ventilation systems TR19 2nd Edition | October 2013 Building & Engineering Services Association
Foreword Type here
GUIDE TO GOOD PRACTICE
Internal cleanliness of ventilation systems TR19 2nd Edition | October 2013 Building & Engineering Services Association
Table of Contents Foreword .................................................................................................. 4 1
Introduction ........................................................................................ 9
2
Protection, delivery and installation standards for maintaining the internal cleanliness of new ductwork prior to commissioning and/or handover ............................................................................... 13 Introduction ......................................................................................... 13 Air movement devices and in line plant and equipment .............................. 14 Notes for designers and specifiers ........................................................... 15 Protection, delivery and installation (‘PDI’) .............................................. 16 PDI level 1 protection ............................................................................ 16 Condition of ducts ex-works ................................................................... 16 Delivery to site ..................................................................................... 17 Installation ........................................................................................... 17 Protection of ductwork risers .................................................................. 17 Downward facing and horizontal duct openings ......................................... 17 Access provisions for on-going maintenance ............................................. 17 Access openings to in-duct plant ............................................................. 17 PDI level 2 protection ............................................................................ 17 Site storage away from the working area ................................................. 18 Installation ........................................................................................... 18 Second fix installation ............................................................................ 18 PDI level 3 (Pre-commission specialist cleaning) ....................................... 18 Summary ............................................................................................. 19 Other important considerations............................................................... 20 Factory/Site sealing of ductwork ............................................................. 20 Hazardous conditions ............................................................................. 20 Site drilling of ductwork ......................................................................... 21
3
Design and access to the internal surfaces of the ventilation system 22
4
Specific considerations for system components ................................. 26 Air handling units & other system components ......................................... 26 Access to air handling units .................................................................... 26 Filters .................................................................................................. 27 Linings ................................................................................................ 27 Moisture .............................................................................................. 27 Heating, cooling coils and heat exchanger coils ......................................... 28 Heat recovery coils, thermal wheels, cross-over coils ................................ 28 Fans .................................................................................................... 28 Sound attenuators ................................................................................ 30 Turning vanes, volume control dampers .................................................. 30 Fire dampers ........................................................................................ 30 Ductwork ............................................................................................. 30 Steel ductwork ..................................................................................... 30
GUIDE TO GOOD PRACTICE
Internal cleanliness of ventilation systems TR19 2nd Edition | October 2013 Building & Engineering Services Association
Flat or oval ductwork ............................................................................. Phenolic ductwork ................................................................................. Glass-fibre reinforced plastic(‘GRP’) ........................................................ Air socks .............................................................................................. Chilled beams ....................................................................................... Fire cladding and fire-rated ductwork ....................................................... Flexible ducts ....................................................................................... Diffusers and grilles .............................................................................. Terminal equipment .............................................................................. Plenum void .........................................................................................
31 31 31 31 31 32 32 32 33 33
5
System risk assessment (inspection/monitoring/testing) ................. 35 Legislation - health and safety law .......................................................... 35 Monitoring (inspection and testing) frequency recommendation .................. 36 Identification and assessment of risk ....................................................... 37 Testing procedures................................................................................ 38 Deposit thickness test (‘DTT’) ................................................................ 39 Preferred vacuum test (‘PVT’) ................................................................ 39
6
Cleaning Methods .............................................................................. 42 Considerations when using dry cleaning methods ...................................... 42 Considerations when using wet cleaning methods ..................................... 42 Mechanical brushing .............................................................................. 43 Compressed air whip/skipper ball ............................................................ 43 Air lance .............................................................................................. 43 Hand wipe............................................................................................ 44 Hand vacuum ....................................................................................... 44 Hand brushing ...................................................................................... 44 Hand scrape ......................................................................................... 44
7
Specific considerations for kitchen extract systems .......................... 46 Design and access to the internal surfaces of the kitchen extract system ..... 49 Cleaning methods ................................................................................. 52 Frequency of cleaning............................................................................ 53 Frequency of cleaning - risk assessment .................................................. 54 Post-clean verification of cleanliness ........................................................ 56 System testing (inspection/monitoring) ................................................... 56 System performance testing................................................................... 58
8
Hazardous contamination .................................................................. 59
9
Verification of cleanliness .................................................................. 61 Acceptable dust accumulation levels for newly installed ductwork ............... 61 Acceptable post-clean level .................................................................... 61 Timing of post-clean verification testing ................................................... 62 Completion report ................................................................................. 62
10 Health and safety ............................................................................... 63 Appendix A
Microbiological contamination ........................................... 66
GUIDE TO GOOD PRACTICE
Internal cleanliness of ventilation systems TR19 2nd Edition | October 2013 Building & Engineering Services Association
Appendix B
Legislation and guidance ................................................... 70
Appendix C
Cleaning contractor selection ............................................ 72
Appendix D
Testing methods ............................................................... 74
Appendix E
Quick guide 1 Air ductwork systems ................................. 78
Appendix F
Quick guide 2 Kitchen grease extract systems .................. 79
Appendix G
Bibliography ...................................................................... 80
GUIDE TO GOOD PRACTICE
Internal cleanliness of ventilation systems TR19 2nd Edition | October 2013 Building & Engineering Services Association
1
Introduction
1.1
The internal cleanliness of ventilation systems is considered important for human comfort and health, energy consumption, system service life and for cleanliness of operations or processes carried out in the ventilated area.
1.2
The guiding principle of this document is that a defined, measurable level of cleanliness should be achieved. In cases of doubt regarding procedures, facilities and methods to achieve cleanliness then this principle defines success or failure.
The first edition of TR/17 established a level of particulate cleanliness verification for both new and existing ventilation systems and an indication of when it is considered appropriate to clean systems in use. The second edition was expanded to include an enlarged section on kitchen extract systems. It established levels of grease surface deposit at which it is appropriate to clean a kitchen extract ventilation system and at which post-clean verification is achieved. The 3rd publication TR/19 incorporated both TR/17 and the former DW/TM2 – Guide to Good Practice Cleanliness of New Ductwork Installation. This included revised guidelines to ensure that new ductwork systems remained protected during the installation period and prior to commissioning. This current TR/19 (second edition) now updates guidance on surface cleanliness testing and includes reference to the new British and European Standard BS EN 15780 Cleanliness of Ventilation Systems which was introduced during 2011. Also in this edition significant changes have been made to highlight the current best practice for ensuring that kitchen extract systems are maintained to minimise the risk of fire associated with grease accumulation. 1.3
This Guide places a responsibility on the designer to clearly state if verifiable cleanliness is required for newly installed ductwork.
1.4
When specifying or agreeing cleanliness criteria on newly installed or existing ducting it is important that all interested parties clearly agree on the cleanliness quality class of each ventilation system as defined by BS EN 15780 (see section 5.14 of this Guide) as each of these classes has a different acceptable levels of dust accumulation.
1.5
Previously legislation and guidance on standards in buildings has been directed towards the design and construction of buildings and
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associated systems. The proper maintenance of building systems is also recognised as crucial to the health, economic and safe operation of occupied spaces. 1.6
The Workplace (Health, Safety and Welfare) Regulation 1992 requires that effective provision should be made to ensure that every enclosed workplace is ventilated by a sufficient quantity of fresh or purified air. Where this ventilation is provided by mechanical means the regulations required those mechanical ventilation systems to be maintained (including cleaned as appropriate) in efficient working order. Failure to carry out these duties is a breach of the Regulations. (Please see Appendix B for further reference.) The Corporate Manslaughter and Corporate Homicide Act 2007 places a much greater corporate responsibility and business risk on organisations in terms of the consequences of health and safety compliance failure, particularly where inadequately cleaned systems heighten the risk of fire and fire spread.
1.7
General ventilation systems (not affected by kitchen grease) as defined, and referred to in this Guide include, but are not limited to, the following:
1.8
Ductwork Air handling units Fan coil and induction units Constant air volume units Variable air volume units Control dampers Attenuators Air terminals Ancillary components associated with the air distribution system.
Kitchen extract systems as defined and referred to in this Guide include, but are not limited, to the following:
Canopy Canopy/extract plenum Ductwork Fans Discharge duct
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Ancillary components associated with the extract system Other extraction systems that may be affected by grease/oil deposits, eg dish wash, pot wash, general kitchen extract ventilation
Fire dampers (where fitted) and attenuators.
Inadequate access to kitchen extract ducting has been shown to be a contributory factor to fires that spread through ducting. The designer therefore has a responsibility to ensure that adequate access is possible both through the building fabric to and into the system; thus ensuring that planned preventative maintenance (“PPM”) for full grease removal is practicable. The designer is advised to seek guidance from a specialist cleaning contractor at the design stage. Section 7 (specific considerations for kitchen extract systems) can be read separately for the convenience of readers solely interested in this aspect of the cleanliness of ventilation systems. 1.9
Table 1 (typical application of system quality classes) is applicable to all systems except kitchen extract systems (which are dealt with in Section 7) and defines the levels of dust deposit at which it is appropriate to clean a general system. The levels of deposit referred to in Table 8 relate to normal nuisance dust and are based on good practice as well as the British and European standard BS EN 15780. Table 13 defines the level of grease deposit at which it is appropriate to clean a kitchen extract system and is again based on fire safety good practice.
1.10
A level of cleanliness is detailed which would verify acceptable cleaning performance for general and kitchen extract systems.
1.11
Measurement methods within this Guide do not apply to microbiological contamination or hazardous materials, such as lead, asbestos, toxic process dusts, etc. Where such materials or contamination are present, specialist advice should be sought. Appendix A gives general information on microbiological contamination. More detailed advice is given in TM26:2000 published by CIBSE (see Appendix E).
1.12
For convenience, two quick reference guides have been included at Appendix E and F, which give a summary of cleaning frequencies and dust/grease accumulation levels for air ductwork and grease extract systems.
1.13
The onus is on the specifier/client to select and clearly define any other additional requirements to be included within the scope of work,
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eg verification responsibility and which ventilation systems and plant are to be included (refer to Section 4). The following items should be specifically quantified:
Any component to be replaced (eg, filter, media, flexible ductwork etc)
Items requiring repair or remedial attention (eg, damaged or corroded ductwork or fittings)
Re-commissioning or testing requirements.
Alternatively, contingency sums should be considered. Appendix C gives advice on the selection of specialist contractors.
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2
Protection, delivery and installation standards for maintaining the internal cleanliness of new ductwork prior to commissioning and/or handover
Introduction 2.1
With the introduction of BS EN 15780 all interested parties should be made aware that there are now three classifications of system types with regard to internal duct cleanliness. The document gives guidance on the system quality class for each of these types of areas (see table 1 below) and the most applicable should be agreed between the installer/building owner and other interested parties prior to the commencement of installation. This British Standard requires a verifiable cleanliness standard to be achieved prior to handover. Acceptable dusts accumulation levels for new ductwork are shown in table below (table 2). Table 1 Typical applications of system quality classes System quality class
Typical examples
Low
Rooms with only intermittent occupancy, eg storage rooms
Medium
Offices, hotels, restaurants, schools, theatres, residential homes, shopping areas, exhibition buildings, sport buildings, general areas in hospitals, general working areas in industries
High
Laboratories, treatment areas in hospitals, high quality offices
Table 2 Acceptable dust accumulation levels in new ductwork Acceptable dust accumulation level
Acceptable dust
Cleanliness quality
Supply, recirculation or secondary
accumulation level
class
air ductwork
Extract ductwork
Low
