TR19 PREVIEW

Building Engineering Services Association Guide to good practice INTERNAL CLEANLINESS OF VENTILATION SYSTEMS TR 19® JULY 2019 www.theBESA.com

Building Engineering Services Association Guide to good practice Acknowledgments INTERNAL The BESA records its appreciation and thanks to the many CLEANLINESS OF persons and organisations who have freely given information VENTILATION on various aspects of this work, in particular to the following SYSTEMS members of the ventilation Hygiene Branch who contributed their knowledge and experience to this later edition: TR/19 Craig Booth Paul Downing George Friend Alan Gregory Gareth Keller Steve Lorriman Gary Nicholls Richard Norman Nick Tregaskes Peter Reid Nick Umfreville 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 978-0-903783-65-1 Publishing history: First published as DW/TM2 (1991) and TR/17 (1998) Second Edition (2002), TR/19 (2005) and TR/19 (2013) Third Edition (2019) ©2019 BESA JULY 2019 BESA Publications Old Mansion House Eamont Bridge Penrith CA10 2BX 01768 860405 [email protected]. www.theBESA.com

Building Engineering Services Association Foreword Guide to good practice As air is invisible there is a tendency to take the quality of the air we breathe for granted. Moreover, given that the average person has an air INTERNAL intake of about 3.4 litres of air every minute, the dangers of an inadequate CLEANLINESS OF or polluted air supply are obvious.This, coupled with the risk of fire VENTILATION from build up of grease deposits in kitchen extract systems and the SYSTEMS expectations of building occupiers and legislators, has resulted in an ever more stringent level of ventilation system cleanliness being required. TR/19 This association first published TR/17 in 1998 in order to give guidance to good practice and to establish standards for testing, cleaning and verification of the internal cleanliness of ventilation systems. The guide was re-published in 2005 to include further improvements to best practice and to incorporate the former publication DW/TM2 – Internal Cleanliness of New Ductwork Installations. To differentiate this expanded edition from its predecessor publication, it was renumbered TR/19. The opportunity was been taken in the second Edition of TR/19 to incorporate reference to the new British and European Standard BS EN 15780 Cleanliness of Ventilation Systems introduced in 2011. Also changes were 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. Kitchen extract systems are not covered by BS EN 15780. In this Third Edition, Section 7 has been withdrawn and has been superseded by TR19® Grease, a new, stand-alone specification for Fire Risk Management of Grease Accumulation within Kitchen Extraction Systems. The guide can be used for new build, upgrade and maintenance of ventilation systems and will directly benefit users of the indoor environment as well as specifiers and consultants. Since its inception in 1998, this guide and its predecessors have been widely accepted within the building services sector and by the UK insurance industry as the standard to which ventilation systems should be cleaned. BESA would like to thank members of the BESA ventilation Hygiene Branch and the many persons and organisations who have contributed to this guide. www.theBESA.com



Building Engineering Services Association 3 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS TABLE OF CONTENTS Page Foreword 2 1 introduction 5 2 new ductwork system cleanliness 8 3 Design and access to the internal surfaces of the ventilation system 11 4 Specific considerations for system components 15 Air handling units & other system components 15 Access to air handling units 15 Filters 15 linings 16 Moisture 16 Heating, cooling coils and heat exchanger coils 16 Heat recovery coils, thermal wheels, cross-over coils 17 Fans 17 Sound attenuators 17 Turning vanes, volume control dampers 17 Fire dampers 18 ductwork 18 Steel ductwork 18 Flat or oval ductwork 18 Phenolic ductwork 18 glass-fibre reinforced plastic(‘gRP’) 18 Air socks 18 chilled beams 18 Fire cladding and fire-rated ductwork 19 Flexible ducts 19 diffusers and grilles 19 Terminal equipment 20 Plenum void 20 5 System risk assessment (inspection/monitoring/testing) 21 legislation - health and safety law 21 Monitoring (inspection and testing) frequency 21 recommendation identification and assessment of risk 22 Testing procedures 23 Preferred vacuum test (‘PvT’) 24 deposit thickness test (‘dTT’) 24

Building Engineering Services Association 4 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS 6 cleaning Methods Page considerations when using dry cleaning methods considerations when using wet cleaning methods 26 Mechanical brushing 26 compressed air whip/skipper ball 26 Air lance 26 Hand wipe 27 Hand vacuum 27 Hand brushing 27 Hand scrape 27 27 7 Specific considerations for kitchen extract systems 28 Section 7 of this document has been withdrawn and superseded by TR19® Grease, a new, stand-alone 29 specification for Fire Risk Management of Grease Accumulation within Kitchen Extraction Systems. 29 8 Hazardous contamination 30 30 9 verification of cleanliness Acceptable dust accumulation levels for newly installed 31 ductwork 31 Acceptable post-clean level 31 Timing of post-clean verification testing completion report 32 10 Health and safety 33 35 Appendix A Annex F from BS En 15780 38 Appendix B Microbiological contamination 39 Appendix c legislation and guidance 41 Appendix D cleaning contractor selection 45 Appendix E Testing methods 46 Appendix F Quick guide 1: Air ductwork systems Appendix H Bibliography

Building Engineering Services Association 5 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS SECTION 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. in 2005 TR/17 was incorporated with the former dW/TM2 – guide to good Practice cleanliness of new ductwork installation and published as TR19®. The second edition of TR/19 updated guidance on surface cleanliness testing and included reference to the new British and European Standard BS En 15780 cleanliness of ventilation Systems which was introduced during 2011. In this Third Edition, Section 7 has been withdrawn and has been superseded by TR19® Grease, a new, stand-alone specification for Fire Risk Management of Grease Accumulation within Kitchen Extraction Systems. 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 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 c for further reference.)

Building Engineering Services Association 6 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS 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: • 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. 1.8 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 • 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. TR19® Grease, a new, stand-alone specification for Fire Risk Management of Grease Accumulation within Kitchen Extraction Systems, can be read separately for the convenience of readers soley interested in this aspect of the cleanliness of Ventilation systems. 1.9 Table 1 (typical application of cleanliness quality classes) is applicable to all ventilation 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 7 relate to normal nuisance dust and are based on good practice as well as the British and European standard BS En 15780. Table 12 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.

Building Engineering Services Association 7 INTERNAL CLEANLINESS OF VENTILATION 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 B gives general information on microbiological contamination. More detailed advice is given in TM26 published by ciBSE. 1.12 For convenience, two quick reference guides have been included at Appendix F and g, 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, e.g. 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 (e.g., filter, media, flexible ductwork etc) • items requiring repair or remedial attention (e.g., damaged or corroded ductwork or fittings) • Re-commissioning or testing requirements. Alternatively, contingency sums should be considered. Appendix D gives advice on the selection of specialist contractors.

Building Engineering Services Association 8 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS SECTION 2 NEW DUCTWORK SYSTEM CLEANLINESS INTRODUCTION 2.1 BS En 15780 ‘ventilation for Buildings - ductwork - cleanliness of ventilation Systems’ describes in detail the requirements for cleanliness of newly installed duct systems. Appendix F of the standard is reproduced as Appendix A of this guide. The standard is based on a verifiable cleanliness outcome. The level of cleanliness varies according to the system cleanliness class that has been adopted for the project (see Table 1). For example: a warehouse system is subject to less rigorous standards than a high quality office or hospital building. The specifier shall clearly define the cleanliness quality class of each system being installed Table 1 (A.1) — Typical applications of cleanliness quality classes (for ventilation systems) Quality Typical examples class low Rooms with only intermittent occupancy e.g. Medium storage rooms, technical rooms High offices, hotels, restaurants, schools, theatres, residential homes, shopping areas, exhibition buildings, sport buildings, general areas in hospitals and general working areas in industries laboratories, treatment areas in hospitals high quality offices 2.2 Advice is also given on protection measures to minimise fouling of ductwork during site handling however this is no substitute for specification of the actual desired cleanliness outcome. 2.3 This Section 2 replaces previous dW/TM2 and TR19 Edition 1 (2005) guidance. 2.4 verifiable measurements using the Preferred vacuum Test provide the ultimate confirmation of success or failure of measures taken to achieve the desired level of cleanliness. These are shown in Table 2:

Building Engineering Services Association 9 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS Table 2 (A.4) – Acceptable dust accumulation levels in new ductwork cleanliness Acceptable dust Acceptable dust quality class accumulation level accumulation level Extract ductwork low Supply, recirculation or Medium secondary air ductwork < 1.8 g/m2 High < 0.9 g/m2 < 1.8 g/m2 < 0.6 g/m2 < 0.9 g/m2 < 0.3 g/m2 dust accumulation which exceeds these levels at time of handover for final commissioning is unacceptable. See also notes below regarding practical measures to establish system cleanliness economically and quickly. 2.5 Please see the decision flow chart at Fig 1 which will help to illustrate the decision- making process. note, that if all parties, including the client representative, agree that a system is visually clean then no further action is needed.

10 Building & Engineering Services Association Fig 1 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS Cleanliness Inspection YES Visually clean? NO Clearly YES unclean? NO Objective measurements Acceptable NO cleanliness Cleaning Veri cation YES Documentation notes for Designers and Specifiers 1 See Appendix A for more detail on Protection delivery and installation advice contained in BS En15780 2 Practical experience shows that due to the various activities that typically occur on construction sites, there is a risk that the installed ductwork will not avoid dust contamination regardless of any measures of protection employed. 3 it should be noted that the specified level of protection can only be achieved if the working environment is compatible. 4 Responsibility for any potential cleanliness testing and additional cleaning requirement should be defined. 5 For practical reasons, inspection, possible testing and cleaning should be programmed after erection but prior to final air commissioning so that a clean system is commissioned and to avoid potential disturbance to the balance.

Building Engineering Services Association 11 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS OTHER CONSIDERATIONS 2.6 The post clean integrity and maintenance of the system is outside the control of the cleaning contractor, it is therefore not appropriate to apply retention sums to cleaning works. 2.7 Factory/Site sealing of ductwork. in certain circumstances, such as clean rooms or other extremely high specification areas, the specifier may require that the internal surfaces of new ductwork are protected during transportation and site storage. This can be achieved by factory sealing all ductwork either by blanking or capping duct ends, bagging small fittings, surface wrapping or shrink wrapping (see important consideration with regard to hazardous conditions, clause 2.8). The specifier must clearly specify this requirement to the ductwork contractor and also to the Main contractor in terms of ensuring dry/clean storage and working areas. 2.8 Hazardous conditions. in certain concentrations some cleaning materials and sealants can pose a risk to operatives. The control of Substances Hazardous to Health Regulations (‘coSHH’) require employers to assess the risk to employees’ health from using hazardous materials and take precautions to minimise that risk. For example, when using internally applied solvent based sealants and adhesives on site, ducts should only be capped-off after an appropriate curing period has elapsed (normally a minimum of 24 hours). ducts should be left to naturally ventilate prior to sealing-off the installed ductwork. 2.9 Site drilling of ductwork. Swarf will be generated during the installation and possibly during commissioning/air balancing, eg test probe covers. Some swarf will therefore remain inside the ductwork unless further cleaning is specified. SECTION 3 DESIGN AND ACCESS TO THE INTERNAL SURFACES OF THE VENTILATION SYSTEM 3.1 in accordance with BS En 12236, determination of load must be considered by the system designer for the additional weight of a person or persons who may gain access to ductwork for the purpose of cleaning or maintenance. 3.2 BESA specification dW/144 covers the provision of access panels for the inspection/servicing of adjacent items of in-line equipment. in a new ductwork system these are the only access panels that a ductwork contractor will provide unless there is a clear indication by the designer/specifier as to their requirements for access to facilitate cleaning survey/inspection or cleaning activity (see Table 3 of this guide). 3.3 This section gives general guidance regarding provisions for the system hygiene inspection/testing and system cleaning of both new and existing ductwork systems. The location of access panels for these purposes is set out in Table 3. A specifier may consider variances to this advice having taken due regard of specific cleaning methods.

Building Engineering Services Association 12 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS 3.4 The precise location, size and type of access would depend upon the system design and the type of ductwork cleaning, inspection and testing methods to be adopted. The advice of the specialist cleaning contractor should be sought at an early stage. 3.5 dW/144 states that the required access panels for inspection/ servicing access to in-line equipment / components only should be installed by the ductwork contractor and that additional panels for cleaning should be installed as and when required by the specialist cleaning company. The specialist cleaning contractor, in addition to taking advantage of openings fitted by the ductwork installer, shall fit any additional cleaning openings themselves, not only in order to suit their specific methods of cleaning but also to suit the practical site conditions relative to the fabric of the building and position of other services. 3.6 All openings shall be made safe and have sealed panels/covers designed so that they can be speedily removed and re-fixed. Therefore multiple set screws and self-tapping screws are not acceptable as a method of fixing panels/covers to an access opening/frame. 3.7 it is essential to note that the tabulated access schemes cannot necessarily be used prescriptively since consideration must be given by the designer to the particular building, services and architectural interfaces and system requirements. The designer’s responsibility under the cdM regulations is to ensure that the system is designed so that it can be safety maintained, inspected and cleaned in accordance with BS En 12236. The designer is therefore advised to seek guidance from a specialist cleaning contractor to ensure that system cleaning of any new design is practicable. 3.8 it is for the designer and the other project parties responsible for the implementation of the design, under cdM “cascade” principles, to ensure that access panels are not obstructed by pipework cable trays or any other obstacle during the building process. consideration should be given to the future use of the building including occupation. 3.9 Access panels in accordance with dW/144 should be suitable for the purpose for which they are intended. They should incorporate quick release catches, sealing gasket and thermal, acoustic and fire-rated insulation properties equal to that of the duct to which the panel is fitted. The panel and aperture should be free of any sharp edges. 3.10 For system hygiene inspection and testing and for system cleaning, Tables 4 and 5 indicate the minimum sizes of access panel required. 3.11 generally, it is acceptable to access a branch duct for cleaning by removal of the flexible duct that connects to the grille plenums. 3.12 For the purpose of cleaning the ventilation system and its component part, the recommended location of the access panels, size and type is aligned with British and European standard BS En 12097.

Building Engineering Services Association 13 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS 3.13 This document reproduces this information in part, so as to establish the location, size and type of access panels, for new build and upgrade of existing ductwork systems. These details are given in Tables 3, 4 and 5. Table 3 location of Access Panels for inspection/Servicing and/or internal cleanliness* in-line equipment location Party responsible for provision of suitable control dampers Both sides access panel Fire dampers Both sides Ductwork contractor Specialist cleaning Heating/cooling/re-claim Both sides coils contractor Attenuators (rectangular) Both sides Attenuators (circular) Both sides up-stream panel down-stream panel Filter sections Both sides Air turning vanes Both sides To suit damper opposite side changes of direction one side in-duct fans/devices Both sides maintenance inlet/exhaust louvre one side intermediate cleaning Panel on both sides panels up-stream panel down-stream panel up-stream panel down-stream panel up-stream panel down-stream panel up-stream panel down-stream panel one-panel to suit up-stream panel down-stream panel one panel to suit To suit frequency specified in TR19® and dW/172 notes to Table 3 1 With regard to new ductwork installations dW/144 table 20 specifies the location of and responsibility for the installation of access doors. 2 other than in the locations shown in Table 3, intermediate access panels should be installed by the specialist cleaning contractor as a minimum every 15 m in horizontal ductwork systems for the purpose of normal usage but not greater than 1m from the throat of a square 90° bend. 3 in the case of flat oval ductwork incorporating internal tie rods it may be necessary to install access doors at more frequent intervals. in the case of vertical ductwork, an access opening at the bottom and top of each riser and at each accessible floor should be provided for cleaning and inspection purposes. 4 Access panels can be positioned to allow access to more than one component depending on ductwork dimensions, distance between components and the cleaning technique used. 5 Access panels should normally be positioned as close as practicably possible to the item to be cleaned (0.5 m maximum). 6 A change of direction is deemed to be a 90° bend and branches. With regard to circular ductwork it is not necessary for there to be an access panel on every change of direction. 7 For access requirements for kitchen extract systems see BESA specification TR19® Grease. 8 Recognising that fire resisting kitchen extract systems need a greater frequency of access panels as detailed in the BESA publication dW/172, ‘Specification for Kitchen ventilation Systems’ and that such panels must be incorporated into the manufacture of the kitchen extract ductwork. in the case of fire-resisting duct systems particular care must be taken to ensure that any retro-fitted access panels are suitable fitted, under licence to the fire- resisting systems manufacturer.

Building Engineering Services Association 14 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS Table 4 Recommended size of openings (rectangular & flat oval) Duct size up to longest Recommended dimension of openings side major axis 300 mm 150 mm 200 mm 300 mm 200 mm 300 mm 450 mm 300 mm 400 mm 450 mm 450 mm ≥500 mm Table 5 Recommended size of openings (circular) Duct size up to Recommended dimension of openings 310 mm 250 mm 150 mm 450 mm 400 mm 300 mm 550 mm 400 mm 300 mm ≥600 mm 500 mm 400 mm note to table 3, 4 & 5 1. For ductwork in dimensions unsuited for mechanised cleaning and where human access is needed, the type and location of access components shall allow the cleaning person to safely and without hindrance enter and exit from the ducts (ref: BS En12097)

Building Engineering Services Association 15 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS SECTION 4 SPECIFIC CONSIDERATIONS FOR SYSTEM COMPONENTS AIR HANDLING UNITS & OTHER SYSTEM COMPONENTS 4.1 To obtain satisfactory conditions of cleanliness, all the components associated with the ventilation system should be included in specific cleaning and maintenance procedures. 4.2 inlets should be protected by weather louvres backed by maximum 12 mm mesh (vermin guard) and situated away from potential sources of contamination. Heavy contamination within inlets prior to filters is common and may include insects, feathers, bird droppings, nesting materials, wind-blown leaves, grass, soil and paper. inlets near roads may suffer carbon based deposits. Badly sited inlets are susceptible to heavy contamination and blockage by airborne particulates and debris. They also act as a first stage, very coarse filtration (‘trash screen’). Regular cleaning is recommended. 4.3 Water entry as droplets or condensation can support mould growth in inlets and make dirt deposits difficult to remove, as well as causing louvres, vermin guards and inlet ductwork to corrode and eventually disintegrate. 4.4 The provision of extra access panels may be required to give operator entry to remove deposits by scraping, vacuuming, brushing or wet methods and to repair louvres, mesh and corrosion damage. 4.5 Where significant bird contamination or mould problems are encountered, a preliminary disinfection before starting work may be required and appropriate protection provided for cleaning operatives. due to the ingress of external and re-circulated deposits and moisture within air inlets and pre-filter inlet ductwork it is a prudent measure to increase the frequency of inspection and cleaning of these sections to prevent conditions worsening and to stop the system fabric degrading. ACCESS TO AIR HANDLING UNITS 4.6 Access to all sections of the air handling units is required for adequate cleaning. occasionally there is no usable access door to the space between sections, for example heating and cooling coils. in this event extra access panels may have to be installed subject to the design of the unit. defective door and filter seals are a common and significant source of inward dirt leakage and filter bypass. FILTERS 4.7 defective or incorrectly fitted filters, or inappropriate filter selection and sizing may present an avoidable dust burden within ductwork systems. if left unattended, significant particulate contamination of the unit and ductwork may occur. Regular inspections of the filter

Building Engineering Services Association 16 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS sections are important to ensure they are not damaged, collapsed or blocked and are correctly seated and sealed against air bypass. A regular filter exchange programme should be conducted to maintain system performance and hygienic conditions. LININGS 4.8 Air handling units, ductwork and other system components may be lined with Machine- Made Mineral Fibre (‘MMMF’) which may or may not be protected by a coating, foil or fabric. damaged linings releasing particles into the air system are common. Foam may be also be used as a lining. This can break down with age to release fine particles. Where damage is observed it must be reported so that it can be made good. 4.9 Many linings are porous and have the capacity to absorb dirt. They require thorough but careful vacuum cleaning with a soft brush head to remove dirt without causing damage. complete dirt removal is unlikely to be achieved. 4.10 Where moisture is present significant microbiological growth within the lining is possible. 4.11 The existing condition of the lining, or potential damage caused by cleaning activities, may necessitate the removal, repair or relining of the ductwork lining interior. consideration should be given to replacement with sealed lining to prevent ingress of moisture. MOISTURE 4.12 Humidification and condensation on chilled surfaces and leakage can cause dampness or in extreme cases standing water resulting in corrosion or excessive microbial growth. Similar problems can occur at droplet eliminators. Poor drainage of condensate from chilled coil drip trays may require cleaning of drain lines and traps. Treatments to prevent microbiological growth contaminating and blocking trays and drain lines are a possible option. 4.13 design and maintenance considerations to protect against proliferation of legionella species are dealt with in AcoP l8 and nHS guidance (see Appendices c & H). HEATING, COOLING COILS AND HEAT EXCHANGER COILS 4.14 coils with very closely spaced fins and/or which are very deep, can suffer blockage due to accumulated dirt, corrosion and hardness deposits. They are prone to severe deterioration of the fins. coils located before filters are particularly vulnerable. Heavily contaminated heat exchangers will operate at low thermal efficiency leading to inefficient plant operation and increased running costs. corrosion of heat exchanger fins and mounting frames, together with microbiological fouling and condensate carry over from the chiller batteries can create a source of contamination downstream of the primary filters. if the coil is in a duct, lack of access for inspection and routine cleaning can result in these being blocked with dirt, restricting air flow through them (methods as used for air handling units apply). Additional access panels to give access to both sides of the coil will usually be required.

Building Engineering Services Association 17 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS 4.15 vacuum brushing, compressed air jetting, water washing, and the application of chemical cleaning methods, singly or in combination may be required. care must be taken to avoid damage to fins. HEAT RECOVERY COILS, THERMAL WHEELS, CROSS OVER COILS 4.16 Stringent building regulations and the need to control and reduce energy costs has led to an increase in the use of heat recovery technology. cross-over coils and thermal wheels are an efficient method of recovering heat from extracted air and transferring it to the incoming air via fins or plate heat exchangers. 4.17 ductwork extraction and recirculation systems will naturally carry varying levels of airborne contaminants, therefore these in-line and intricate heat recovery systems are open to dirt fouling and subsequent reduction in heat exchange performance. Regular inspection and an appropriate programme of decontamination are advised. FANS 4.18 Fans, motors and drives may be heavily contaminated especially if oil or grease has leaked. impellers may have heavy deposits on the blades. For full in-situ cleaning, partial dismantling and, possibly, the creation of extra access panels in fan casings, subject to manufacturer approval, may be required. Fans can vary in size greatly. The types typically found within ventilation plant are axial flow, centrifugal or bifurcated. it is essential to ensure fans are electrically isolated and locked off before carrying out inspection or cleaning works. SOUND ATTENUATORS 4.19 Sound attenuators (also called ‘silencers’) may be located within air handling plant or situated remotely in ducts. These usually have linings covered with woven fabric or perforated sheet metal. dirt readily accumulates in silencers and their porous nature makes complete cleaning impossible. careful vacuum brushing with a soft brush head or very gentle application of compressed air are possible cleaning methods. 4.20 Where damage has occurred which may allow the release of MMMFs, consideration should be given to repair or replacement. TURNING VANES, VOLUME CONTROL DAMPERS 4.21 These tend to accumulate dirt which can affect their operation and will require access panels on both sides to allow full cleaning and surface restoration. 4.22 volume control dampers can either be manually set or automatically controlled. They are designed to regulate (balance) the airflow (volume) throughout the various branches of the distribution ductwork. Found on all sizes of duct, both supply and extract, they can also be circular plate or iris type design on small round ductwork. These in-line components can become heavily fouled, especially in re-circulation or extract systems. Manually set volume control dampers should have the ‘as found’ setting marked indelibly to aid resetting.

Building Engineering Services Association 18 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS FIRE DAMPERS 4.23 Fire dampers should be inspected on a frequency not exceeding 2 years in accordance with BS9999 for correct function and condition in compliance with the requirements of the Regulatory Reform Fire Safety order 2005 and physically cleaned when required. inspection and functional testing of smoke/fire dampers should be separately specified. DUCTWORK STEEL DUCTWORK 4.24 The most common form of ventilation distribution material is galvanised steel sheet. it can be constructed in a range of sizes and profiles, most common are rectangular and circular, however flat oval is also in use. These systems are typically of a rigid construction and are often hidden from normal view above false ceilings etc. Access is typically gained via installation of access doors either during installation or at the time of necessary cleaning works. on larger ductwork total man access may be necessary (see 3.1 and 10.5) FLAT OR OVAL DUCTWORK 4.25 due to its design this ducting contains many steel tie rods to provide strength and stability. consideration must be given to installing sufficient access doors and the method of cleaning due to restricted access. PHENOLIC DUCTWORK 4.26 This is a light weight pre-insulated, rigid ductwork system made from a phenolic compound and lined inside and out with a foil finish. it is a weaker structure compared to galvanised steel and care should be taken when cleaning not to damage the surfaces or over load with weight. careful consideration should be given to access points to ensure the thermal quality and air tightness is maintained. Man access into this type of ductwork is not recommended and more frequent access points should be created to facilitate cleaning. GLASS FIBRE REINFORCED PLASTIC ‘GRP’ 4.27 These ductwork systems are generally used where the contents of the ductwork contain harmful or corrosive chemicals. They are typically associated with local exhaust ventilation (‘lEv’) systems. They are well sealed and most commonly associated with extraction only. doors are typically prefabricated and sealed with specialist gaskets or mastic and bolted shut to ensure air tightness. AIR SOCKS 4.28 These can be permeable textile or plastic-coated ducts which are held in-situ by a series of runners and zips or velcro fastenings. They can only be used for supply air as they rely on positive air pressure to inflate and offer good even air distribution. Air socks require regular cleaning and have a relatively limited lifespan compared to steel ductwork.

Building Engineering Services Association 19 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS CHILLED BEAMS 4.29 Passive, active or multi-service chilled beams are relatively low maintenance devices but do require occasional cleaning due to dust collection from both tempered supply air and re- circulated air from the occupied space. FIRE CLADDING AND FIRE RATED DUCTWORK 4.30 Access doors fitted must be of the same construction and must not compromise the fire protection integrity of the system. Safety notice: - some older fibrous boarded products may contain asbestos. Always treat with caution and, if suspected as possibly containing asbestos, then consult a specialist before disturbing. FLEXIBLE DUCTS 4.31 Flexible ducts trap dirt in the corrugations. This dirt can be difficult to completely remove if the corrugations are deep and/or compressed together. light weight foil, plastic flexible or aged flexible are liable to damage. cleaning methods must be adjusted to account for the type of flexible duct. Brush methods require soft bristle brushes and gentle application. compressed air methods may require a pressure reduction to avoid tearing the duct material. 4.32 it may be necessary to remove and extend flexible ducts to release dirt from folds. 4.33 decay of the material of construction, or difficulties in releasing flexible ducts from their connection spigots without causing damage may make replacement a better option than cleaning. DIFFUSERS AND GRILLES 4.34 Where possible these should be removed for cleaning. Washing to remove grease and staining may be required. 4.35 diffuser/grille locations and orientation should be marked or recorded if they are to be taken away for washing, so that they can be returned to the correct location. opposed blade dampers should have the ‘as found’ setting marked to aid resetting. 4.36 certain grille and diffuser arrangements may be installed such that they cannot be practicably removed for cleaning, eg linear diffusers or those trapped by partition walls. in-situ cleaning by air line and extraction to capture dislodged deposits may be used. 4.37 diffusers may have plenum boxes, possibly containing dampers behind them, which also require cleaning. Access will be required to permit cleaning or air jetting and extraction methods.

Building Engineering Services Association 20 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS TERMINAL EQUIPMENT 4.38 Equipment such as fan coils, mixing boxes, air socks, vRv, cAv, vAv, induction units and unit air conditioners may be included in a cleaning programme. 4.39 Wall and sill mounted equipment is frequently obstructed by difficult to move furniture and fittings, preventing or hindering access for cleaning. Responsibility for moving obstructions should be defined by the specifier. 4.40 ceiling mounted equipment may be obstructed by services and structures preventing the opening of access panels and withdrawal of internal components. Some terminal units have filters which may require cleaning or which are disposable. contractual responsibility for supplying replacement filters will require definition by the specifier. 4.41 Terminal units may be lined or include attenuator sections. Maintenance activity, ageing and erosion by air flow may have resulted in damage to the lining allowing fibre escape. if damage to the lining occurs remedial action should be taken immediately. The lining may have accumulated dirt within its matrix. The limited access to all air passages, especially labyrinth passages in attenuators within terminal units and the presence of delicate porous linings can prevent total dirt removal. 4.42 gentle vacuum brushing or air jetting, plus high volume extraction may be required. Some units have air jet nozzles or small air passages which become blocked with dirt. This dirt can form a hard deposit which requires mechanical removal with suitable tools to chip or ream it away. Jet nozzles may also require washing. 4.43 it is important for the specifier to define the extent of cleaning for induction units, eg whether secondary and mixed air surfaces only are included or whether typically less accessible primary air surfaces (plenum box) are also included. PLENUM VOID 4.44 ceiling and floor void plenums may be used as an integral part of the air distribution system and should therefore, be subject to the same hygiene consideration as other system components. Regard should be given to the selection of cleaning technique(s) in view of the different construction materials used. in particular if MMMF is in place, careful consideration should be given to either cleaning or replacing such insulation where loose fibres are present. 4.45 Plenums are often exposed brickwork, mortar and plastered surfaces. Their rough texture accumulates and traps particulates and can quickly become fouled and stained. Sealing coarse brick surfaces with an approved non-solvent sealant would reduce degradation and crumbling of the surfaces and enable dry cleaning methods to be adopted to remove accumulated dusts. Alternatively brickwork could be rendered or clad to provide a smooth and easily cleanable surface.

Building Engineering Services Association 21 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS SECTION 5 SYSTEM RISK ASSESSMENT (inSPEcTion/MoniToRing/TESTing) 5.1 ventilation systems by their very nature will accumulate contamination to a degree which will be influenced by the quality of the incoming air, filtration, design, maintenance and usage. over time varying types of contamination will accumulate to levels which may detrimentally influence the quality of the supplied air and hence may affect the health of building users. contaminant levels can build to such an extent that they provide the added risk of fire propagation. LEGISLATION HEALTH AND SAFETY LAW 5.2 The Management of Health & Safety at Work Regulations 1999 impose a duty on every employer to make a suitable and sufficient assessment of: (a) the risks to the health and safety of his employees to which they are exposed whilst they are at work, and (b) the risks to the health and safety of persons not in his employment arising out of or in connection with the conduct by him of his undertaking. 5.3 Regulation 5 of the Workplace (Health, Safety and Welfare) Regulations 1992 imposes a duty to clean mechanical ventilation systems “as appropriate”. Regulation 6 states, “effective and suitable provision shall be made to ensure that every enclosed workplace is ventilated by a sufficient quantity of fresh or purified air”. 5.4 AcoP6 (52) relating to Regulation 6 of the Workplace (Health, Safety and Welfare) Regulations, 1992 states that “mechanical ventilation systems (including air conditioning systems) should be regularly and properly cleaned, tested and maintained to ensure that they are kept clean and free from anything which may contaminate the air”. British Standard BS En 15780 provides benchmarks to define cleanliness and dirtiness. MONITORING INSPECTION AND TESTING FREQUENCY RECOMMENDATION 5.5 AcoP5 (41 & 42) relating to Regulation 5 of the Workplace (Health, Safety and Welfare) Regulations 1992 makes specific reference for the need for regular maintenance including inspection and testing at suitable intervals. BS En 15780 details the frequencies. The assessment frequencies described in Table 6 should be considered as the minimum recommendations and the necessity of increasing them will depend on the environment conditions, on the activity and on mechanical and human conditions in both the building and its surroundings.

Building Engineering Services Association 22 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS in most cases inspection frequency should be specified rather than cleaning frequency as the amount of contaminant identified during inspection may alter the actual required cleaning frequency. Please refer to BESA specification TR19® Grease for inspection and testing of kitchen grease extract systems. Table 6 Recommended minimum regular inspection/monitoring intervals (in months) according to system (cleanliness) quality class (‘SQc’) inspection and Testing intervals (months) SQc AHu Filters(2) Wet areas(1) Ducts Terminals low 24 12 12 48 48 Medium 12 12 6 24(3) 24(3) High 12 6 6 12(4) 12(4) notes to Table 6 1 Wet areas of the ventilation systems comprise humidification, cooling coils, condensate trays and other ancillary or associated items of plant containing these elements. 2 Filters should be inspected and maintained according to the manufacturer’s recommendations, with these intervals as the minimum. 3 For compliance with HTM03, this frequency should be increased to 12-monthly. 4 For compliance with HTM03, this frequency should be increased to 3-monthly. IDENTIFICATION AND ASSESSMENT OF RISK 5.6 A suitable and sufficient risk assessment is required to identify and assess the risk of contamination levels in a ventilation system. Such contamination may have accumulated to a degree which could be detrimental to both the building users and processes being undertaken within the building. Precautionary measures to reduce risk should therefore be identified and remedial measures put into action. The person on whom the statutory duty falls is required where specialist testing is necessary to have access to competent help in conducting the assessment. They should ensure that whenever specialist advisors are used that the advisors have sufficient understanding and expertise of the work activity they are undertaking. 5.7 The scope of a risk assessment should include, but not be restricted to: (a) provision of suitable access points, if not present. (b) visual inspection. This may be assisted by the use of equipment such as cameras, endoscopes and robotic ccTv with appropriate records such as photographs and video footage. (c) quantitative duct surface dust measurement by an approved method. Where grease or adhered deposits are clearly the issue then only the deposit thickness test (‘DTT’) method or the wet film thickness test method (‘WFTT’) detailed in section 7 and Appendix E, should be used. A minimum of three test points per

Building Engineering Services Association 23 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS system should be included. A specific representative number of tests should be agreed prior to the risk assessment taking place. An average should be calculated across all tests conducted on each system and used to determine whether it is appropriate to clean the system. However, individual results that are excessively high may indicate a need for local attention. Where it has been decided that microbiological colonisation of system surfaces could be a risk factor then suitable microbiological sampling should be agreed as part of the risk assessment. (d) The following components should be subject to cleanliness inspection as a minimum: • Fresh air intakes, air handling unit including filters and coils and selected in-duct plant and ancillaries such as attenuators, fire dampers, volume control dampers, heat exchangers, vAv boxes, etc. • A selection of ductwork, including (but not limited to) changes of direction, terminations, straight horizontal and vertical ducts. • A selection of terminal equipment such as flexible ducts, grilles, diffusers and equipment, eg induction and fan coil units. The number of inspection locations and tests should be clearly defined by the specifier. The client should be given the opportunity to witness the sample testing of ductwork surfaces. (e) The inspection of maintenance records and air hygiene management log book including: i. record drawings ii. filter inspection and replacement regimes iii. previous condition monitoring records iv fire damper operational test records, and v. previous cleaning or remedial work records. The significant findings of the risk assessment should be recorded (if there are five or more employees) and should detail recommendations for remedial actions and on-going monitoring programmes. TESTING PROCEDURES 5.8 BS En 15780 Annex H gives a summary of test methods and units that can be used for evaluating cleanliness. 5.9 Testing procedures are defined in this guide that should be used to establish whether or not it would be appropriate to clean a mechanical ventilation system. These provide reasonable and practicable ways of satisfying the Regulations and AcoPs relevant to the cleanliness of ventilation systems as detailed above. Specific guidance on testing methods is given in Appendix E.

Building Engineering Services Association 24 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS 5.10 it should be noted that there is a clear difference between tests to monitor ventilation system surface condition and tests to monitor ‘ventilation air quality’. This guide is concerned with surface condition tests. These will indicate the potential for the system to release contaminants into the air at any point in the future and affect subsequent system performance/energy efficiency, whereas air quality tests will indicate contaminants that are actually in the air, but only at the time of collecting the sample. 5.11 Monitoring of system condition through regular testing will allow the rate of accumulation to be ascertained and the appropriate action to be determined and budgeted for. in certain instances it may be considered necessary to set more frequent inspection intervals where specific risks have been identified in the event of particle release into the airstream (eg, operating theatre supply). 5.12 in order to establish an objective method for determining when a ventilation system is considered dirty in terms of particulate and hence when it would be appropriate to clean, two alternative testing methods are recommended as follows, these can be used during risk assessment or routine monitoring. Both test methods provide an objective method of measuring internal duct floor surface deposits: PREFERRED VACUUM TEST ‘PVT’ 5.12.1 This method requires on site sample collection and subsequent off site laboratory analysis. it determines the mean deposit weight in grams per m2 and is suitable for circular, flat-oval and rectangular duct types. This method is recommended by BS En 15780 and applies to three cleanliness quality classes (for ventilation systems). DEPOSIT THICKNESS TEST ‘DTT’ 5.12.2 Suitable for on site assessment and ventilation system survey reports for flat metal duct surfaces during risk assessment where immediate results are required. The dTT method determines the mean surface deposit in terms of micron thickness. Since the introduction of TR/17 in 1998, a result above 60µm has defined a cleaning requirement for supply and recirculation systems (180µm for extract systems). due to the introduction of cleanliness quality classes (for ventilation systems) within BS En 15780 the levels for dTT have been aligned with the British Standard in table 7 below. noTE: Separate testing and contaminant levels specifically for kitchen extract systems are detailed in BESA specification TR19® Grease. 5.13 The PvT - a development of the vacuum test - forms part of the new British and European Standard BS En 15780 previously mentioned. 5.14 BS En 15780 has a requirement to categorise each system type as low, medium or high class depending on the areas being served. These levels of cleanliness quality class (for ventilation systems) should be generally applied as follows:

Building Engineering Services Association 25 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS Table 1 (Repeated from section 2) Typical applications of cleanliness quality classes (for ventilation systems SQc Typical examples low Rooms with only intermittent occupancy, eg storage rooms Medium offices, hotels, restaurants, schools, theatres, residential homes, High shopping areas, exhibition buildings, sport buildings, general areas in hospitals, general working areas in industries laboratories, treatment areas in hospitals, high quality offices To comply with the system cleanliness quality classification PvT samples should show results below the limit values given in Table 7. 5.15 Table 7 below sets out what would be considered as acceptable contamination levels in existing ‘in service’ ductwork. Above these levels cleaning would be necessary. These contamination levels should not be confused with: (a) post-clean level set for verification of cleanliness ‘following a system clean’, this is far more stringent and these levels are detailed in section 8, or (b) cleanliness levels for ‘newly installed ductwork’. These levels are detailed in Table 2. Table 7 Acceptable contamination levels in Existing Ductwork System Acceptable Acceptable Acceptable Quality contamination levels – contamination levels – contamination levels – class Supply Ductwork Re-circulation or Extract Ductwork Secondary Air Ductwork D.T.T P.v.T D.T.T P.v.T D.T.T P.v.T low 90µm <4.5g/m2 120µm <6.0g/m2 180µm <9.0g/m2 Medium 60µm <3.0g/m2 90µm <4.5gm2 180µm <9.0g/m2 High 12µm <0.6g/m2 60µm <3.0g/m2 180µm <9.0g/m2 notes to table 7 1. Prior to using this table a definition of the relevant ventilation system(s) cleanliness quality class(es) should be decided. 2. The table should be used to define when it is considered appropriate to clean the system(s) using either the preferred vacuum testing (PvT) or deposit thickness testing (dTT) measurement methods. 3. in the case of any extract system direct to atmosphere a reduction of airflow by 15% or more would equally define the need to clean the system. 5.16 The results of any monitoring undertaken must be recorded in a suitably consistent format, assessed by the responsible person and any necessary maintenance actions identified implemented. Records of all monitoring and maintenance tasks undertaken should be retained within a system hygiene log book.

Building Engineering Services Association 26 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS SECTION 6 CLEANING METHODS 6.1 This guide is not intended to be prescriptive in relation to the method of cleaning, as there are many existing and emerging technologies available depending upon the type of deposit to be removed. To conform to this guide, the actual application of the methods listed in Table 8 must be capable of achieving the required result 6.2 ductwork cleaning should ideally be undertaken in the direction of the air flow to prevent the risk of cross contamination between cleaning shifts. on buildings with multiple zones (e.g. floors) these works can be planned to take advantage of the natural cut off points at the risers. careful planning at the pre-contract stage is essential in ensuring a successful cleaning regime. CONSIDERATIONS WHEN USING DRY CLEANING METHODS 6.3 in all cases where mechanical cleaning techniques are used, the particulate should be collected using an air movement and containment machine (negative air pressure extraction techniques). This will generally require appropriate filtration and should assist in the containment of contaminants. CONSIDERATIONS WHEN USING WET CLEANING METHODS 6.4 Moisture can assist in the growth of micro-organisms and the system should be thoroughly dried prior to commissioning/re-commissioning. The introduction of cleaning chemicals or biocides should only be considered where a risk assessment has been carried out, the details recorded and any adverse effects of the applied chemicals have been assessed and determined with appropriate safe procedures set out in a formal method statement. Steam cleaning and high pressure water wash are not recommended for ductwork that is situated above ceilings or in sensitive areas unless carried out in a controlled manner to contain leakage. Again, procedures must take account of operative safety and should be set out in written form. careful consideration should be given to the use of chemicals and/or water for cleaning fan motors, bearings, electric motors; also surfaces that are porous, e.g. internally lined ductwork, attenuators, fibre board ductwork etc, as permanent damage may result. Before applying wet cleaning methods, care should be taken to ensure that condensed vapours and cleaning fluids can be removed from the ductwork system. MECHANICAL BRUSHING 6.5 This method of ductwork cleaning typically applies to ducts not exceeding 600 diameter or 500 ´ 500, as above this size the effectiveness can be limited. The basic principles of this method are based around the agitation/disturbance of the duct surface deposits in conjunction with negative pressure high volume extraction to remove and collect the deposits.

Building
Engineering Services Association 27 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS COMPRESSED AIR WHIP/SKIPPER BALL 6.6 Much like mechanical rotary brushing, this method of cleaning is best applied to ducts typically not exceeding 600 diameter or 500 x 500. This method uses a compressed air source and compressed air line with a specially designed nozzle on the end which blasts the ductwork with compressed air thus removing the deposits. This method of duct cleaning is normally best employed when the deposits within a duct are only loosely adhered to the surfaces. Again, this method is used in conjunction with a negative pressure high volume extraction unit to remove and collect the deposits. AIR LANCE 6.7 This method of cleaning utilises a compressed air line with a gun and trigger attached to one end that can be used to dislodge localised deposits. it is best utilised when cleaning difficult to access, intricate areas or delicate areas which may become damaged by more aggressive cleaning techniques. it is important to consider the collection of the deposits when using this method as there is a risk of not being able to collect all of the deposits which have been dislodged and this could result in cross- contamination. normally it would be best to use the air lance to blow the deposits into a contained location where they can then be removed. HAND WIPE 6.8 This method involves physically wiping all of the internal surfaces of the duct to remove deposits. utilise tak rags, anti-static dusters and lint free cloths to simply hand wipe all internal components. cleaning agents may also be applied in accordance with coSHH using pressurised sprayers; all residues must be fully removed from the surface with clean water. HAND VACUUM 6.9 one of the most common methods applied when manually cleaning ductwork is to hand vacuum the internal deposits. This is best achieved using a high efficiency filtered vacuum cleaner fitted with an appropriate brush head to agitate the deposits. HAND BRUSHING 6.10 This method simply involves brushing the deposits off of the surface of the larger ducts for collection.

Building Engineering Services Association 28 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS HAND SCRAPE 6.11 With particularly heavy or greasy deposits, it may be necessary to utilise hand scraping techniques. The best way of achieving results is to use a suitable sharp scraper to remove the majority of the deposits and complete this process by the application of an appropriate cleaning agent to break down the remaining residues. Following activation of cleaning agent the hand wipe technique should be employed to remove the loosened residues. Table 8 cleaning methods generic Energy Method of removing Typical application name source deposit Mechanical Rotary compressed Brushing the surface of dry deposits that in brushing air and/or the ductwork using some places could electricity mechanical action require agitation to remove from the ductwork surfaces Air compressed directional jet nozzle on dry, loose deposits. whip/nozzle air the end of a flexible not to be used hose where cross contamination could be an issue Air lance compressed Air gun with a internal coils/linear air trigger/lance that can be diffusers used to direct compressed air locally Manual Hand wipe Manual Wiping of the surface ultra clean using a medium environments appropriate to the purpose Hand scrape Manual Removing heavy Strongly adhered deposits by hand deposits in areas scraping where arm or man access is possible Hand Manual Sweeping the surface Heavy, loose brushing using an appropriate deposits in areas brush and collection where arm or man device access is possible Hand Electricity/ Removal of deposits by loose deposits in areas vacuum Manual means of vacuum where arm or man access is possible Wet Wet vacuum Electricity/ Removing liquid by AHus/humidification Manual means of wet vacuum chambers chemical Mechanical/ Application of suitable gross soiling clean Manual chemicals to soften or dissolve deposits Hand Manual Washing of surfaces large AHus, air using an appropriate intake plenums etc. wash/wipe cleaning agent and grease laden surfaces Steam/High Electricity High pressure system concrete intake pressure used to dislodge/dissolve plenums and grease water wash deposits laden surfaces note: Where mechanical cleaning methods are used these need to be combined with negative air pressure extraction techniques in order to control the removal of contaminants.

Building Engineering Services Association 29 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS SECTION 7 SPECIFIC CONSIDERATIONS FOR KITCHEN EXTRACT SYSTEMS Section 7 of this document has been withdrawn and superseded by TR19® Grease, a new, stand- alone specification for Fire Risk Management of Grease Accumulation within Kitchen Extraction Systems. For any works that require compliance with the TR19® Grease specification, you must expressly state in any tender documents/contracts that TR19® Grease applies, in addition to TR19®, to ensure the correct services can be applied to projects where required. Stating TR19® only will not encompass the TR19® Grease specification. SECTION 8 HAZARDOUS CONTAMINATION 8.1 deposits typically removed from ventilation ductwork systems, including grease and carbonised deposits from kitchen extract systems, are not generally regarded as hazardous waste. 8.2 A variety of specifically hazardous contaminants may be found in ventilation systems, especially in industrial or laboratory lEvs whose performance falls under coSHH Regulations. Hazards may include precipitated toxic, carcinogenic or otherwise hazardous particulates, condensed vapours or pathogenic micro-organisms. 8.3 ventilation systems that incorporate humidification, contain cooling coils, or where water ingress/condensation into the system components could occur, should be assessed for the risk of microbiological contamination, in particular legionella bacteria and mould. 8.4 Asbestos presents a variety of possible hazards including: (a) contamination of ventilation system air and surfaces by asbestos fibres (b) system construction materials which may be disturbed in gaining access to the system (eg, cladding or panelling) (c) components, such as flexible ductwork, flexible connections, gaskets, etc containing asbestos. 8.5 Where asbestos needs to be removed it shall only be undertaken by trained or licensed specialist contractors. 8.6 Work within health care or pharmaceutical premises may necessitate staff to work in areas that may increase the potential to develop allergies or contract illnesses. Adequate controls and health monitoring may be required in these circumstances.

Building Engineering Services Association 30 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS 8.7 The responsible person operating the building in which the work is being carried out must define any likely or known hazards, including advising of any other work or processes which may pose a risk in accordance with coSHH Regulations and contractors have a duty to satisfy themselves that the known hazards are accounted for. 8.8 Specific risk assessments should be carried out to identify required health and safety control measures and relevant site/system specific method statements provided to deal with hazardous contamination This may require additional specific training to be provided for the contractor’s employees before works commence. 8.9 As part of the risk assessment any contaminant or microbiological sampling that may be required for safety reasons shall be undertaken and results assessed to identify any control measures required which shall be built into the method statement before work commences. Analysis of samples should be undertaken by an appropriate accredited laboratory. SECTION 9 VERIFICATION OF CLEANLINESS 9.1 There are two levels of cleanliness verification specified here, the first concerns ‘acceptable dust accumulation’ in newly installed ductwork, the second concerns an ‘acceptable post-clean level’ for ductwork following a cleaning operation. in both cases the primary method of assessment is visual. ACCEPTABLE DUST ACCUMULATION LEVELS FOR NEWLY INSTALLED DUCTWORK 9.2 Table 2 (from Section 2) for acceptable dust accumulation in new ductwork, repeated below defines acceptable dust accumulation (cleanliness) levels on new ductwork as handed over from builder to user. in practice this means the quantity of fouling which is deemed acceptable. Should the results of testing be greater than these levels defined in Table 2 then cleaning should be carried out to meet an acceptable post-clean level, as defined in 9.6 below. Table 2 (Repeated from Section 2) Acceptable dust accumulation levels in new ductwork cleanliness Acceptable dust accumulation level Acceptable dust quality class Supply, re-circulation or secondary accumulation level low air ductwork Extract ductwork Medium High <0.9 g/m2 <1.8 g/m2 <0.6 g/m2 <1.8 g/m2 <0.3 g/m2 <0.9 g/m2

Building Engineering Services Association 31 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS ACCEPTABLE POST CLEAN LEVEL 9.3 After cleaning the ductwork and other relevant components, surfaces should be visibly clean and capable of meeting the required acceptable post-clean level. 9.4 in addition to visual assessment verification for most normal duct cleaning work, the method of establishing acceptable post-clean level is to use the Preferred vacuum Test (‘PvT’) see Appendix E (based on BS En 15780) for technical details. The deposit thickness test is not suitable for post clean verification. 9.5 if specified or in the event of non-agreement of the visual assessment then verification should be carried out as defined in 9.4, the responsibility for the cost of PvT verification should be agreed prior to contract commencement. 9.6 The acceptable post-clean level is <0.3 g/m2, using the PvT. TIMING OF POST CLEAN VERIFICATION TESTING 9.7 it should be noted that post-clean verification testing should take place immediately after cleaning to avoid any possibility of post-clean contamination outside of the control of the cleaning contractor. The client should be given the opportunity to witness testing of ductwork surfaces. COMPLETION REPORT 9.8 on completion a comprehensive report should be provided. This should clearly state the following information: • The ventilation system(s) cleaned • cleaning methods used • verification results (if specified) • Pre- and post-clean photographic records • Any faults identified that could impact future hygiene • Additional works carried out (if any) • coSHH data on any chemicals used for cleaning or biocidal treatment • Recommendations for future testing and cleaning requirements. For kitchen extract systems, a report should be provided as set out in BESA specification TR19® Grease.

Building Engineering Services Association 32 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS SECTION 10 HEALTH AND SAFETY 10.1 A risk assessment and safety method statement for the work should be prepared by a competent person and where necessary approved by the client before allowing the work to be started. 10.2 coSHH assessments should be carried out for any substances to be used or encountered as a contaminant in the course of cleaning should also be made. 10.3 The risk assessment, method statement and coSHH assessments must be understood by all those carrying out the works and it is the responsibility of the site supervisor(s) to ensure that the control measures and safe system of working are adhered to. • consideration should also be given to safe high level access to both internal and external ductwork and associated plant. • A site specific risk assessment must be undertaken by a supervisor prior to commencement of each shift. Any changes to required control measures highlighted must be communicated to all relevant staff. 10.4 BES\"’s Risk Management and coSHH manuals give comprehensive guidance on how these legally required documents should be prepared. 10.5 Physical entry into ductwork should be avoided wherever possible, but where it is deemed necessary, the Health & Safety, confined Spaces & Working at Height Regulations shall be considered and the guidance in the Approved code of Practices to the Regulations closely followed. The ductwork itself and any supports or hangers must be assessed as to their ability to support the additional weight of the operative and any equipment he may take into the duct (refer to BS En 12236). 10.6 Where physical entry to the system has been agreed, the client should ensure that any other processes taking place at the time of system cleaning do not pose a risk of, eg noxious or hazardous substances/gases entering the system, being cleaned and areas being worked in. 10.7 Appropriate personal protective equipment (‘PPE’), as detailed in the Method Statement, must be worn at all times. All PPE must be selected by a competent person as suitable for the purpose and must fit the individual operative properly (Health & Safety (PPE) Regulations). 10.8 A procedure for regular checking and cleaning of PPE must be set up and defects remedied by repair or replacement before any operatives are put at risk. 10.9 Particular monitoring or controls may be needed to deal with hazardous particulate, microbiological or gaseous contaminants or with hazardous cleaning processes, eg use of solvents, coatings, steam or pressurized water, etc.

Building Engineering Services Association 33 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS APPENDIX A We reproduce here, by kind permission of the British Standards institute, ‘Annex F (informative) ductwork – Specific installation guidance’ of BS En 15780 ACCEPTABLE DUST ACCUMULATION NEW DUCTWORK Acceptable dust accumulation (new ductwork) defines acceptable cleanliness levels on new ductwork as handed over from builder to user. in practice this means the quantity of fouling which is deemed acceptable. Table F.1 — Acceptable dust accumulation levels in new ductwork cleanliness Acceptable dust Acceptable dust quality class accumulation level accumulation level Extract air ductwork low Supply, recirculation or Medium secondary air ductwork < 1.8 g/m2 High < 0.9 g/m2 < 1.8 g/m2 < 0.6 g/m2 < 0.9 g/m2 < 0.3 g/m2 construction sites are inevitably dusty workplaces and so there are severe practical difficulties in keeping duct systems clean. if defined levels of cleanliness are required, then it is often necessary to carry out deliberate post-installation cleaning immediately before commissioning, in order to achieve defined, measurable levels of cleanliness. F.2 PROTECTION, DELIVERY AND INSTALLATION PDI guidance is given below regarding the preparation and protection of ductwork during manufacture and installation with a view to minimising unnecessary contamination of duct systems. Table F.2 — Recommendations concerning protection, delivery and installation PDi level Factory Protection Protection Site cap Post- Basic Pdi seal during during clean off on installation transit site storage site clean no no no no Risers no # only intermediate no no Yes Yes Yes not unless Pdi shown to Yes * be Advanced Yes * Yes * Yes * Yes * necessary# Pdi Yes notes to table F2 1. (#): if inspection and testing indicates that the cleanliness is not considered acceptable due to a failure to meet acceptable dust accumulation levels for the relevant cleanliness quality class, then despite the general guidance in the table above, cleaning would in fact be required 2. (*): Since the ductwork will be cleaned post-installation many costly and onerous procedures such as capping during transport can be dispensed for most installations.

Building Engineering Services Association 34 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS BASIC LEVEL condition of ducts ex works: ductwork leaving the premises of the manufacturer may include some or all of the following: — internal and/or external self-adhesive labels or marking for part(s) identification; — exposed mastic sealant; — light zinc oxide coating on the metal surface; — a light coating of oil on machine formed parts; — minor protrusions into the airway of rivets; — screws, bolts and other jointing devices; — internal insulation and associated fixings; — discoloration marks from plasma cutting process. The ductwork is not generally wiped down or specially cleaned at this level unless specified. Delivery to site: unless otherwise specified, ductwork delivered from the premises of the manufacturer is not protected. installation: Before the installation of individual duct sections they should be inspected to ensure that they are free from all debris but not be wiped or specially cleaned. Protection of ductwork risers: All risers should be covered to prevent the entry of debris into the duct. in respect of the safety of personnel, full regard should be given to requirements of health and safety at work. downward facing and horizontal duct openings: These are not covered. INTERMEDIATE LEVEL The intermediate level includes the following requirements in addition to the provisions of the basic level. Site storage: The area provided for storage should be permanently clean, dry and protected from site dust and this may require a boarded floor and water resistant covering. installation: The working area should be clean and dry and protected from the elements. The internal surfaces of the ductwork sections should be wiped to remove excess dust immediately prior to installation. open ends on complete ductwork and overnight work-in-progress should be sealed. Prior to the installation of air terminal devices, any remaining protective end covers should be removed before installing the terminal device with the damper in closed position. ADVANCED LEVEL Advanced level includes the following requirements in addition to the provisions of the intermediate level.

Building Engineering Services Association 35 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS Since the ductwork will be cleaned post-installation many costly and onerous procedures such as capping during transport can be dispensed for most installations. in some cases further protection methods may be applied by means of voluntary documents. Production and site delivery: All self-adhesive labels for part identification should be applied to external surfaces only. Site storage: A clean, dry and dust free environment should be provided for the storage of ductwork prior to installation. installation: The working area should be clean, dry and dust free. Special considerations: The oil-residues may be only mentioned as a recommendation, because at this time no practicable test method for the use in field is available. An agreement about allowed microbiological colonisation should be separately specified, including realistic verification criteria. For most uses clean installation is normally enough to keep the level of microbiological colonisation negligible.) APPENDIX B MICROBIOLOGICAL CONTAMINATION B.1 Microbiological colonisation of air handling system surfaces by non-pathogenic, environmental micro-organisms is normal. Poor hygiene conditions will lead to colonisation of potentially harmful or pathogenic growth. The presence of moisture tends to encourage microbiological growth. B.2 Microbiological aspects of ventilation hygiene are covered in TM26 published by the chartered institute of Building Services Engineers (‘ciBSE’). details of this publication are given in Appendix H. The following Table is reproduced by kind permission Table 3 of TM26 states the following classification of surface sampling microbial limits: category colony forming units (cFu per 10 cm2) low less than 10 Medium 10 to 19 High 20 and above TM26 identifies the following actions following surface sampling: • Should the microbial counts from a particular general area (such as the AHu) indicate localised microbial contamination, ie more than 50% of samples in the “high” category, then the cleaning of that area should be considered as an appropriate action. • it is considered that cleaning of the entire system should be recommended where, on average, more than 25% of the samples is in the “high” category.

Building Engineering Services Association 36 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS SAMPLING METHODS Before biocidal treatments are undertaken to any areas there should be a quantitative monitoring regime of sampling in place that justifies the requirement for the biocidal treatment. This approach will cover a broad spectrum of indications of the system condition but it will not identify specific contaminant types, it will involve looking for Total viable content. in instances where problems have already been identified then qualitative sampling to identify the specific contamination type may prove beneficial as it could provide evidence as to what is causing the contamination. The protocol for surface sampling techniques can be found in Section 9 of ciBSE TM26. B.3 Biocidal treatment should be carried out in conjunction with removal of the source of contamination, eg dirt and/or moisture. Biocidal treatment must not be used as a substitute for physical cleaning and removal of any deposits. it should be noted that Health Technical Memorandum 03-01: Specialised ventilation for healthcare premises Part B: operational management and performance verification states in point 5.23 that “on completion of cleaning, the ductwork should not be “fogged” with chemicals”. it does however recommend in 5.19 “AHus should be vacuumed-out and /or washed down internally as necessary to remove obvious dust and dirt”. BIOCIDAL TREATMENT B.4 Where it has been decided that microbiological colonisation of system surfaces should be controlled, care must be taken to ensure that the biocide is safe for site users and for operatives. B.5 There is a hierarchy of treatments for the control of organisms as follows (in descending order of severity): • Fumigation - The killing of large organisms including insects, mammals, etc. usually all micro-organisms would be killed by highly toxic methods, but some methods exist where by mammals will be killed by denial of oxygen and this may not be effective against micro-organisms. • Sterilisation - The killing of all micro- organisms leading to nil growth, usually involving highly toxic methods. • Disinfection - The killing of pathogenic organisms and radical reduction of microbiological colonisation to very low levels. • Sanitisation - The reduction of microbiological colonisation to lower levels. B.6 care should be taken to specify the level of control which is actually required, with the important proviso that the level of hazard associated with the process of biocidal treatment should be the minimum to achieve the required objective. in most circumstances, sanitisation treatment will suffice. The risks and costs associated with more hazardous treatments should be avoided unless specifically required.

Building Engineering Services Association 37 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS B.7 Biocidal treatments should be subject to specific risk assessments taking account of at least the following parameters: (a) nature of microbiological hazard, eg known pathogen or normal environmental micro-organisms. Where an air system is known to contain pathogenic micro-organisms, suitable pre-treatment should be carried out to make the system as safe as reasonably practicable, prior to any work being carried out on the system. (b) nature of treatment, e.g. chemicals and method of application. (c) Protection of operatives, e.g. type of PPE. (d) isolation of third parties, e.g. carrying out treatment whilst the building or served area is unoccupied. if the building is not fully vacated, the area served by a system should be carefully defined to avoid any exposure of third parties to treatment. (e) Protection of site, e.g. consideration should be given to inadvertent leakage of treatment chemicals. (f ) in order to avoid any possibility of adding to the indoor air chemical contamination, active biocide should not normally remain within air distribution systems. (g) The biocide manufacturer’s guidelines must always be followed. B.8 The specification should include a definition of the method of verifying the effectiveness of the treatment including the number and type of microbiological samples to be taken and their analysis, e.g. in-house or third party laboratory. ciBSE TM26 states that three samples in four should be classed as “low” as per TM26 table 3 and with none classified as “high” in order for a section to be classified as satisfactorily clean. notes for the specifier 1 none of the four biocidal treatments noted above should be considered as a substitute for cleaning. 2 A coSHH Assessment and Product data Sheet should be available for any proposed biocide and a copy retained in the system log. This information should demonstrate the suitability of the biocide for use in an HvAc system with regard to health and safety of occupants and operatives, and its compatibility with the materials of construction. 3 The space served by the system to be treated should be capable of being effectively isolated for the period of time recommended by the biocide manufacturer. Where this is not possible, stringent control measures, eg reversal of supply air flows, should be employed to preclude any release of biocide into occupied areas. 4 it should not be assumed that mechanical cleaning of the system alone using the methods described in Table 8 of this guide will remove all microbiological content. Where microbiological contamination is identified chemical biocidal treatment may need to be added following the cleaning process.

Building Engineering Services Association 38 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS APPENDIX C LEGISLATION AND GUIDANCE C.1 legislation and guidance on standards in buildings is largely orientated towards the design and construction of buildings and associated systems. increasingly the proper maintenance of building systems is recognised as crucial to the healthy, economic and safe operation of occupied spaces. Relevant legislation and guidance includes but is not restricted to the following. C.2 Health and Safety at Work Act 1974 lays down that employers or persons concerned with premises owe the “common duty of care” both to employers and others who may use or visit the premises. They are required to exercise this duty “so far as is reasonably practicable”. C.3 The control of Substances Hazardous to Health (‘coSHH’) Regulations. This requires an employer to make a formal assessment of health risk from hazardous substances, which includes human pathogens or any dusts present in substantial quantities in the air. Regulation 7 (1) requires the employer to prevent exposure of his employees to substances hazardous to health, or where this is not practicable, to ensure that any exposure is adequately controlled. under these Regulations, local exhaust ventilation systems dealing with hazardous substances are required to be checked regularly to ensure they are performing efficiently. See HSg258 controlling airborne contaminants at work. See also HSE SR27 Controlling cooking fumes. C.4 The occupiers’ liability Act 1984 imposes a duty of care on an occupier of premises to prevent (so far as is reasonably practicable) risk to others of injury, which includes any disease and impairment of physical or mental condition. C.5 The Workplace (Heath, Safety and Welfare) Regulations 1992 (l24) Regulation 6 for ventilation states that: Effective and suitable provision shall be made to ensure that every enclosed workplace is ventilated by a sufficient quantity of fresh or purified air remains intact. The associated Approved code of Practice gives ‘practical advice on how to comply with the law’. For ventilation, it states in AcoP6 (52); Regulation 6, that mechanical ventilation systems (including air-conditioning systems) should be regularly and adequately cleaned. They should also be properly tested and maintained to ensure that they are kept clean and free from anything which may contaminate the air. The associated AcoP5 (41) Regulation 5, has been revised and reads: An ‘efficient state’ means that the workplace and the equipment, devices and systems mentioned in these Regulations should be free of faults likely to affect the health, safety or welfare of workers and provide an adequate level of hygiene. if a potentially dangerous defect is discovered, the defect should be rectified. guidance 6 (58) reminds that some ventilation systems are water based and that suitable legionella precautions need to be taken in line with l8 legionnaires disease Approved code of Practice and guidance The control of Legionella bacteria in water systems. C.6 The Management of Health and Safety at Work Regulations 1997: require employers to carry out risk assessements, make arrangements to implement necessary measures, appoint competent people and arrange for appropriate information and training

Building Engineering Services Association 39 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS C.7 Health and Safety Executive: HSg202 General Ventilation in the Workplace Guidance for Employers describes general ventilation and fresh air requirements for ordinary workplaces. it restates the legal requirements and cites the BESA and ciBSE as able to provide information on testing for likely contaminants in ductwork and on cleaning. C.8 The Regulatory Reform (Fire Safety) order 2005 requires measures to reduce the risk of fire on the premises and the risk of the spread of fire on the premises. C.9 BS9999 code of practice for fire safety in the design, management and use of buildings lays out all aspects of fire safety strategy. C.10 Sick Building Syndrome Health and Safety Executive Guidance Note HS(G) 132 gives guidance on how to deal with sick building syndrome. C.11 Legionnaires Disease - the HSE Approved Code of Practice L8 gives guidance on how to deal with the control of legionellosis including legionnaire’s disease. C.12 Ventilation for buildings - ductwork and hangers and supports - requirements for strength BS En 12236 gives guidance on requirements for strength requirements to support additional weight during the cleaning process. C.13 Cleanliness of ventilation systems BS En 15780 gives guidance on surface cleanliness testing and standards of cleanliness to be achieved in various quality classes and for new, used and cleaned ductwork. APPENDIX D CLEANING CONTRACTOR SELECTION D.1 The following qualification criteria should be considered when selecting specialist cleaning contractors. D.1.1 EXPERIENCE • number of year’s operation as ventilation hygiene specialist. • demonstration of track record with project references. • Total number of field operatives directly employed full-time in ventilation hygiene works. • Qualifications of their staff. As a minimum this should include the BESA green Book Training Scheme or equivalent.

Building Engineering Services Association 40 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS D.1.2 AFFILIATION • Membership of appropriate trade bodies such as the BES\", EvHA or similar. D.1.3 QUALITY ASSURANCE • Work with quality systems or to accredited quality standards such as iSo 9001 or independent auditing of work by competent qualified assessors. • Qualifications and technical training of staff, e.g. BES\" green Book Scheme or equivalent. • Provide evidence of work quality by providing post clean verification reports for every project. D.1.4 HEALTH AND SAFETY • Health and safety policy and description of safe methods of work specific to ventilation hygiene works. • Records of training and competency. • Availability of professional health and safety advice. • Recognised awards. • Safety/accident records. • Membership, registration or approval of appropriate Health & Safety organisations such cHAS, Safe contractor, oHSAS 18001 or similar. D.1.5 INSURANCE • Full details of any professional indemnity, employers’ liability, public liability and contractors’ All Risks Policy, clearly stating any scope and limitations on cover. D.1.6 FINANCIAL To have the financial and operational resources appropriate to the proposed size of contract to be undertaken.

Building Engineering Services Association 41 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS APPENDIX E TESTING METHODS E.1 DEPOSIT THICKNESS TEST ‘DTT’ Test equipment E.1.1 instrument to be used is an electromagnetic induction type thickness gauge with statistics and a non-contact measuring tip. E.1.2 calibration foils required 250 µm, 50 µm and 25 µm. Accuracy of measurement E.1.3 The accuracy of the machine should be within +/-3 µm. Procedure for the measurement of deposit thickness on galvanised ducting systems E.1.4 calibrate the instrument according to the manufacturer’s recommendations using the certified foils provided. E.1.5 Place a measuring template (250 x 160 mm or equivalent surface area) over the surface to be tested, marking the four corners with a marker pen. Take a minimum of 20 readings randomly within the test area, recording the highest, lowest and mean values obtained. E.1.6 Thoroughly remove the deposit coating using resin impregnated cloth and replace the grid into the same position as previously, lining up the pre-marked corners. E.1.7 Take a further 20 readings as previously, again recording the highest, lowest and mean values obtained. E.1.8 To determine the thickness of deposit subtract the mean reading obtained in E.1.7 from the mean reading in E.1.5. E.2 PREFERRED VACUUM TEST ‘PVT’ Test equipment E.2.1 Air pump: A high volume air sampling pump capable of drawing 15 l/min through a cassette containing 37 mm matched weight or pre-weighed filters.

Building Engineering Services Association 42 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS E.2.2 Filter media: 37 mm mixed cellulose ester (‘McE’) matched weight or pre- weighed filters (0.8 μm pore size) in three piece cassette. if pre-weighed filters are used, care has to be taken to desiccate samples at pre-weighing and post-exposure weighing to counter-act possible humidity effects. other size sampling filters (pore size 0.8 mm) may be used, and care should be taken to ensure that smaller diameter filters (<37 mm) are not over-loaded, ie they are recommended only for post-clean verification. E.2.3 calibration: Air volume rate calibration device that is accurate to ± 5% at 15 l/min. E.2.4 Template: Approximately 0.4 mm thick, 0.01 m2 sampling area, typically 10 cm × 10 cm. other shapes can be used to suit different sampling locations. SAMPLING PROCEDURE E.2.5 inspect visually the surfaces. E.2.6 Secure template to surface to be sampled so that it will not shift position during sample collection. The template to lay flat against the surface to be sampled. check that the surface to be sampled is dry and that the fans are not running when the sampling is being conducted. E.2.7 Remove protective plugs from cassette. E.2.8 Attach outlet end of cassette to pump tubing. Attach a 5 cm length of suction tube to the inlet side of the cassette. E.2.9 Adjust air flow using appropriate calibration device to 15.0 l/min. E.2.10 vacuum the open area of the template by scraping the inlet tube across the entire exposed area. Move the suction tube at a rate not greater than 5 cm/s. E.2.11 After the surface has been vacuumed, remove the tubing and replace the plugs in the capsule. E.2.12 Mark the cassette (unless pre-marked) with an indelible pen. A code may be used to protect client confidentiality. A log should be kept to correlate the code with other important information such as job site, location in ductwork, date, etc. E.2.13 Send the cassette to an independent laboratory for weighing using a precision balance of at least 4-point accuracy.

Building Engineering Services Association 43 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS ANALYSIS PROCEDURE E.2.14 in the case of post-clean verification measurement, the filters alone are weighed, i.e. the difference between the two matched weight filters, or the gain in weight on the pre-weighed filter gives the raw result. E.2.15 in the case of measurement of probable dirty surfaces, where loose dust is likely to have been captured in the sampling capsule but not impinged on the filter(s), a different analysis methodology is employed as follows: (a) The entire cassette is weighed. Method for matched weight filters (b) The cassette housing is weighed after the filters and loose dust have been removed and put to one side. (c) The bottom (clean) of the matched weight filters is weighed and the value multiplied by 2. The total dust collected in the cassette is calculated as (a-b-c). Method for pre-weighed filter (d) The cassette housing is weighed after the filter and loose dust have been removed and put to one side. (e) The weight gain on the pre-weighed filter is measured. The total dust collected in the cassette is calculated as (a-d+e). E.2.16 The laboratory will report results in grams (g) per the sampled area (100 sq cm). The raw results should be converted into g/m2 by multiplying by 100, and an assessment offered in general terms to comprise the report to the client. E.3 WET FILM THICKNESS TEST ‘WFTT’ TEST EQUIPMENT E.3.1 A precision gauge capable of measuring wet film thickness from 50 to 800 µ microns at suitable increments (including 200). Toothed combs typically used to measure wet paint film thickness are suitable. E.3.2 Alternatively an electro-magnetic induction gauge as described in E.1.1 - E.1.3, may be used, but care must be taken to avoid compression of soft grease films.

Building Engineering Services Association 44 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS ACCURACY OF MEASUREMENT E.3.3 The accuracy of the WFTT gauge will be defined by a reputable manufacturer and will typically be better than ± 5 µm. E.3.4 it is most important to ensure that the gauge is held strictly perpendicular to the substrate, since holding the gauge at an angle off 90° will tend to exaggerate the measured result. E.3.5 gauges subject to regular or hard use should be of sufficient durability to withstand wear, or be regularly replaced. PROCEDURE FOR THE MEASUREMENT OF GREASE DEPOSIT THICKNESS ON HARD SURFACES USING A TOOTHED COMB E.3.6 using the outer side, or tooth, of the comb, slide it along a surface to reveal a clean start point of bare metal. E.3.7 With the comb held upright and the outer posts in contact with the revealed duct surface, slide it through the deposit for 100 mm. For circular ductwork, slide around the circumference of the duct. E.3.8 Examine any tracks left by the teeth that are slightly graduated in height to the outer posts. The lowest (“clean”) tooth, which has not touched the deposit indicates the maximum deposit thickness. The result should be given as between the lowest “clean” tooth and the adjacent tooth that has a track mark in the deposit, in microns (µm). The measurement should be uniform along the length of the 100 mm long test area. if it is not, re-measure to establish a reliable representative result. E.3.9 clean the gauge before carrying out further measurements.

APPENDIX F Building Engineering Services Association INTERNAL CLEANLINESS OF VENTILATION SYSTEMS QUICK GUIDE 1: AIR DUCTWORK SYSTEMS The following Quick guide summarises the acceptable dust accumulation levels for various types of systems as tested using the Preferred vacuum Test (P.v.T) method and defined and explained throughout this document. For details of the P.v.T method and procedure please refer to the #&4\" TR/19; (2013)‘internal cleanliness of ventilation Systems’ Appendix E. newly installed Acceptable Dust/contamination levels Post clean verification inspection and Testing intervals (Months) Existing Ductwork System Typical Acceptable Acceptable Acceptable Acceptable Acceptable Acceptable Acceptable AHu Filtersº Wet Ducts Terminals Quality Example Dust Dust contamination contaminatoin contamination Dust Dust Areas levels – Supply levels – Extract class Accumulation Accumulation levels – Re- Accumulation Accumulation * low levels – levels – Ductwork circulation or Ductwork+ levels – levels – Extract Secondary Air Extract Medium Supply, Re- Ductwork D.T.T± P.v.T D.T.T± P.v.T Supply, Re- Ductwork circulation or Ductwork circulation or High Secondary Air Secondary Air D.T.T± P.v.T Ductwork Ductwork Rooms with 2 2 222 2 2 24 12 6 48 48 only <0.9g/m <1.8g/m 90µm <4.5g/m 120µm <6.0g/m 180µm <9.0g/m <0.3g/m <0.3g/m intermittent occupancy e.g. 2 2 222 2 2 12 12 6 24# 24# storage rooms offices, hotels, <0.6g/m <1.8g/m 60µm <3.0g/m 90µm <4.5g/m 180µm <9.0g/m <0.3g/m <0.3g/m restaurants, 2 2 222 2 2 12 6 6 12 12 schools, theatres, <0.3g/m <0.9g/m 12µm <0.6g/m 60µm <3.0g/m 180µm <9.0g/m <0.3g/m <0.3g/m residential homes, shopping areas, exhibition buildings, sport buildings, general areas in hospitals, general working areas in industries laboratories, treatment areas in hospitals, high quality offices * Wet areas of the ventilation systems comprise humidification, cooling coils, condensate trays and other ancillary or associated items of plant containing these elements + Extract systems should be cleaned when airflow through the system reduces by 15% or more. if such measurement is not practical, then the gravimetric dust level measurement above may be used º Filters should be inspected and maintained according to the manufacturers recommendations with these intervals as the minimum # For compliance with HTM03 this frequency should be increased to 24 monthly ± d.T.T levels have been aligned with the British Standard to accommodate various system quality classes 45

Building Engineering Services Association 46 INTERNAL CLEANLINESS OF VENTILATION SYSTEMS APPENDIX G BIBLIOGRAPHY • BES\" DW/144 - Specification for sheet metal ductwork. ISBN 978-0-903783-64-4 • BES\" DW/172 - Specification for kitchen ventilation systems. ISBN 0-903783-29-0 • B&4\" SFg 20 - Standard maintenance specification for building services. • British Standard 5720 - Code of practice for mechanical ventilation and Air Conditioning in Buildings. ISBN 0580107183 • British Standard En 15780 – Ventilation for buildings – ductwork – cleanliness of ventilation systems. ISBN 978 0 580 74008 4 • British Standard BS 9999 Code of practice for fire safety in the design, management and use of buildings. ISB 9780580546631 • British Standard En 12236 Ventilation for buildings, ductwork hangers and supports. Requirements for strength. ISBN 0580394573 • BSRiA Facilities Management Series FMS1/1997 - Standard specification for ventilation hygiene. ISBN 0860224554 • BSRiA Facilities Management Series FMS1/1997 - Guidance to the specification for ventilation hygiene. ISBN 0860224546 • BSRiA 2001 - Commissioning air systems application procedures for buildings AG 3/893. ISBN 0860225917 • ciBSE - Commissioning code air distribution systems. Code A. ISBN 090095373X • ciBSE - TM26: Hygienic maintenance of office ventilation ductwork. ISBN 1903287111 • ciBSE – TM13: Minimising the risk of Legionnaires Disease (ISBN 978-1-906846-33-6 • FPA – RC44 Fire risk assessment of extract ventilation for the catering industry. ISBN 1902790421 • Fire Precautions (Workplace) Regulations 1997 No 1840 Fire Precautions (Workplace) (Amendment) Regulations 1999 • HSc HSE BooKS 1996 - Workplace (Health, Safety and Welfare) Regulations 1992. Approved code of practice and guidance L24. ISBN 0717604136 • HSE HS(g)132 guidance note - How to deal with sick building syndrome. ISBN 0717608611 • HSE HSg258 2008 – Controlling airborne contaminants at work. ISBN 9780717662982 • HSE information Sheet - Ventilation of kitchens in catering establishments. Catering sheet No. 10 • HSE l8 legionnaire’s Disease The control of Legionella bacteria in water systems. Approved code of practice & guidance. ISBN 0-7176- 1772-6 • HSE l101 - Safe work in confined spaces. ISBN 0717614050 • HS g202 General ventilation in the workplace guidance for employers ISBN 0 7176 1793 9 • Fire Protection Association - Recommendations for fish and chip frying ranges RC 16a FPA recommendations for cooking equipment (other than fish and chip frying ranges) RC16b • nHS - Estates Health Technical Memorandum HTM 2025 - Ventilation in health care premises. Part 1 - Management policy. ISBN 0113217439 Part 2 - Design considerations. ISBN 0113217528 Part 3 - Validation & verification. ISBN 0113217420 Part 4 - Operational management. ISBN 0113217412 • Stationery office 2002Si 2677 - Control of Substances Hazardous to Health Regulations. 2002 ISBN 0110429192 • Swedish national Board of Housing, Building and Planning general guidelines 1992: E - Checking the performance of ventilation systems NOTE: The European/British Standards and other documents listed are those available at the time of publication. Users should ensure that they consult the latest version.



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