DW 144

Specification for Heating and Ventilating Contractors’ Association Sheet Metal Ductwork DW/144 DW/l44 Specification for Sheet Metal Ductwork Low, medium and high pressure/velocity air systems 1998 Copyright © 1998 by the Heating and Ventilating Contractors’ Association All rights reserved ISBN 0-903783-27-4 Further copies of this publication are available from: Publications Unit Heating and Ventilating Contractors Association Old Mansion House Eamont Bridge Penrith Cumbria CA10 2BX Tel: 01768 864771 Fax 01768 867138 e-mail: hvcapublications@hvwelfare.co.uk THE INDUSTRY STANDARD Ken Parslow Chairman Executive Committee Ductwork Group 1996-98 or more than a decade-and-a-half, the DW/142 Specification for Sheet Metal Ductwork published by the Heating and Ventilating Contractors’ Association has gained national and international recognition as the industry standard against which the quality of ductwork manufacture and installation can be judged In recent years, however, it has become increasingly evident to the members of the HVCA Ductwork Group that the developments in technology and working practices which have taken place since the drafting of DW/142 have rendered obsolete significant parts of the document It was an acknowledgement of this state of affairs which led the Technical SubCommittee of the Ductwork Group, ably chaired by Edgar Poppleton, to undertake the task of producing a radically revised specification which would promote best practice and quality standards well into the next Millennium This new publication — designated DW/144 — represents the direct result of that initiative The new specification recognises the computer age — with special reference to CAD/CAM procedures and techniques — and the international performance standards established by the Committee for European Normalisation (CEN), as well as the need to update and consolidate much of the information contained in the original DW/142 publication and its Addendum A companion volume During the drafting process, the Technical Sub-Committee has consulted widely with individuals and organisations throughout the building services and construction sectors in order to ensure that the new specification fully reflected the current the “state-of-the-art” in terms both of technical expertise and industry best practice I firmly believe that this process has resulted in a publication which clearly demonstrates the high level of professionalism which exists within the ductwork community — and I take this opportunity of thanking all those who have contributed to its production In particular, my thanks go to Edgar Poppleton and his colleagues on the Technical Sub-Committee, to Keith Elphick for the provision of invaluable technical consultancy, and to Ductwork Group secretary Gareth Keller for overseeing the project as a whole F MAINTAINING QUALITY L ike most industries, the ductwork sector Class A, B and C air leakage characteristics, must be prepared continually to innovate in mandatory testing Class C only; • order to survive and prosper A key element in that innovation process is the updated appendices on galvanising after manufacture, stainless steel, pre-coated steel, timely review and updating of quality standards to aluminium, Eurovent and galvanised material, ensure that they continue to offer realistic bench- plus a bibliography; • marks to which all professional individuals and organisations can perform The development of this new Specification for Sheet Metal Ductwork — designated DW/144 — has been carried out with that objective in mind In the 16 years since the publication of its predecessor, DW/142 — and in the ten years since the supplementary volume Addendum A appeared Edgar Poppleton Chairman • • Technical Sub-Committee Ductwork Group — many technical advances, changes in working practices and regulatory introductions and amend- • transport, handling, storage and interface with DW/TM2 Guide to Good Practice — Internal Cleanliness of New Ductwork Installations; an overview of fire-rated ductwork; a new appendix on inspection, servicing and cleaning access openings (the default inclusion of Level should be noted); a new section on standard component drawings — incorporating a framework of nomenclature, and a description of drawing symbols, abbreviations and rules — which is intended to reduce ments have taken place The common performance standards for duct- • work being developed by the Committee for European Normalisation (CEN), for example, had ambiguity and promote common understanding; a rewritten description of all forms of dampers, for which I am indebted to Bill Clark and John Mawdsley of the HEVAC Association to be taken fully into account during the drafting process Similarly, notice had to be given to the I take this opportunity to acknowledge the per- provisions of the Control of Substances Hazardous mission granted by the Sheet Metal and Air to Health (COSHH) and Construction (Design and Conditioning Management) Regulations, neither of which had (SMACNA) of the USA for the use of its tie rod been issued when DW/142 was published specification (designer approval required) Contractors’ National Association It is not possible — nor, I think, desirable — to And I also include a plea on behalf of ductwork include in this foreword an exhaustive catalogue of constructors to be allowed to make the final choice the points of difference between this specification and its predecessor These will clearly emerge of components and techniques within the parame- from a detailed reading of the text specification to satisfy performance characteristics ters set by the designer, and allowed within this I should, however, like to take the opportunity It will, of course, be clear to anyone who has to highlight a few topics which I believe to be of ever taken on such a task that the production of this particular significance They are: specification has involved a colossal input in terms • • • • • • • • • the omission of high-pressure Class D (in order to conform to European practice); of industry consultation and from a wide variety of the highlighting of information to be provided by the designer; identify for special mention the end-sealing of ducts and explosion risks; members Keith Waldron and the late Keith Angood; the removal of standard sizes of rectangular current members Chris Collins, Stuart Howard, ducts; Brian James and — last but by no means least — the omission of cleated joints; Jim Murray; technical consultant Keith Elphick; and the acceptance of proprietary flanges certificated to DW/TM1 no longer illustrated in detail; Ductwork Group secretary Gareth Keller the consolidation into the document of coverage of hangers and supports; importance of ensuring that all ductwork is manu- the addition of a note on linings, along with their cleaning considerations; efficient, effective and free of risk the consolidated graphical representation of significantly in the achievement of this objective individuals, a number of whom I should like to They are: former Technical Sub-Committee Finally, may I remind readers of the crucial factured and installed in a manner which is safe, The publication of DW/144 is intended to assist Acknowledgements The HVCA wishes to record its sincere thanks to the following members — past and present — of the Technical Sub-Committee of the Ductwork Group, who contributed their time, knowledge and experience to the production of this document Edgar Poppleton (chairman) Keith Angood Chris Collins Stuart Howard Brian James Jim Murray Keith Waldron Technical Consultant: Keith Elphick Ductwork Group Secretary: Gareth Keller Other Ductwork-Related Publications DW/143 DW/151 DW/171 DW/191 DW/TM1 DW/TM2 DW/TM3 TR/17 A Practical Guide to Ductwork Leakage Testing Specification for Plastic Ductwork Guide to Good Practice for Kitchen Ventilation Systems Guide to Good Practice: Glass Fibre Ductwork Acceptance Scheme for New Products: Rectangular Cross Joint Classification Guide to Good Practice: Internal Cleanliness of New Ductwork Installations Guide to Good Practice for the Design for the Installation of Fire and Smoke Dampers Guide to Good Practice: Cleanliness of Ventilation Systems Copies of the above publications are available from: Publications Unit Heating and Ventilating Contractors Association Old Mansion House Eamont Bridge Penrith Cumbria CA10 2BX Tel: 01768 864771 Fax 01768 867138 e-mail: hvcapublications@hvwelfare.co.uk – – DW/131 DW/121 DW/122B DW/112 DW/132 DW/141 DW/142 DW/l42 Previous Sheet Metal Ductwork Specifications Ductwork Specification for High-Velocity Air Systems (Circular) Standard Range of Rectangular Ducting Sheet Metal Ductwork Specification for High-Velocity Air Systems (Rectangular) Specification for Sheet Metal Ductwork (Low-Velocity Low-Pressure Air Systems) (Rectangular and Circular) — Metric Specification for Sheet Metal Ductwork (Low-Velocity Low-Pressure Air Systems (Rectangular and Circular) — British Standard Range of Rectangular Ducts and Fittings — Metric and British Units Specification for Sheet Metal Ductwork (High-Velocity High-Pressure Air Systems) (Rectangular, Circular and Flat Oval) — Metric Specification for Sheet Metal Ductwork (Low and High-Velocity/ Pressure Air Systems) (Rectangular, Circular and Flat Oval) — Metric Specification for Sheet Metal Ductwork (Low, Medium and High Pressure/Velocity Air Systems) Specification for Sheet Metal Ductwork Addendum A (Low, Medium and High Pressure/Velocity Air Systems) 1963 1967 1968 1969 1969 1970 1970 1977 1982 1988 Contents Page Notes 10 Part One - Technical Information to be provided by the designer Introduction Standards Components Particular Requirements 11 11 11 11 Part Two - Standards Application Ductwork Classification and Air Leakage Materials Ductwork Construction and Joint Sealing 13 13 13 14 Part Three - Rectangular Ducts Rectangular Duct Sizes 10 Construction 10.1 General 10.2 Steel Thicknesses 10.3 Longitudinal Seams 10.4 Cross Joints 10.5 Stiffeners 10.6 Ductwork Galvanised After Manufacture 10.7 Fastenings 11 Fittings 11.1 Standardisation of Fittings 11.2 Stiffeners 11.3 Splitters 11.4 Turning Vanes 11.5 Branches 11.6 Change Shapes 11.7 Expansions and Contractions 11.8 Sealant 16 16 16 16 16 16 16 16 16 17 17 27 27 27 27 27 29 29 29 29 29 Part Five - Flat Oval Ducts 15 Standard Sizes and Sheet Thicknesses 16 Construction (Spirally wound) 16.1 General 16.2 Longitudinal Seams 16.3 Cross Joints 35 35 35 35 35 35 35 35 35 35 35 Part Six - Hangers and Supports 19 General 43 Part Seven - General 20 Access/Inspection Openings 21 Regulating Dampers 22 Fire Dampers 23 Smoke Dampers 24 Combination Smoke and Fire Dampers 25 Flexible Ducts 26 Flexible Joint/Connections 27 Protective Finishes 28 Connections to Building Openings 29 Internal Duct Linings 30 Thermal Insulation 31 Kitchen Ventilation 32 Fire Rated Ductwork 33 Standard Component Drawings and Abbreviations 15 15 15 15 15 15 15 Part Four - Circular Ducts 12 Standard Sizes 13 Construction 13.1 Longitudinal Seams 13.2 Cross Joints 13.3 Fastenings 14 Fittings 14.1 Standardisation of Fittings 14.2 Nominal Diameters 14.3 Sheet Thickness 14.4 Sealing of Joints 16.4 Fastenings 16.5 Stiffening 17 Construction (Straight Seamed) 18 Fittings 18.1 General Construction Requirements 18.2 Standardisation of fittings Part Eight - Appendices Appendix A Air Leakage from Ductwork Appendix B Identification of Ductwork Appendix C Guidance Notes for the Transport, Handling and Storage of Ductwork Appendix D Ductwork Systems and Fire Hazards Appendix E Hot Dip Galvanizing after Manufacture Appendix F Stainless Steel for Ductwork Appendix G Pre-Coated Steel Appendix H Aluminium Ductwork Appendix J Eurovent Appendix K Summary of BS.EN10142: 1991 Continuously Hot-Dip Zinc Coated Mild Steel Strip and Sheet for Cold Forming Appendix L ‘Design Notes for Ductwork’ (CIBSE Technical Memorandum No 8) Appendix M Guidance Notes For Inspection, Servicing and Cleaning Access Openings Appendix N Bibliography Appendix P Conversion Tables 47 48 49 50 51 51 52 53 53 54 54 54 54 54 75 80 82 83 85 86 89 90 91 92 93 94 95 97 List of Tables Table Page Part Two - Standards Ductwork Classification and Air Leakage Limits 10 Part Three - Rectangular Ducts Constructional Requirements Low Pressure up to 500Pa Constructional Requirements Medium Pressure up to 1000Pa Constructional Requirements High Pressure up to 2000Pa Fastening Centres Part Four - Circular Ducts Standard Sizes Spirally-Wound Ducts Straight-Seamed Ducts Permitted fastenings and maximum spacings Fittings Sheet Thicknesses Part Five - Flat Oval Ducts 11 Standard sizes and sheet thicknesses 12 Stiffening requirements low and medium pressures 13 Stiffening requirements high pressure 14 Permitted fastenings and maximum spacings Part Six - Hangers and Supports 15 Supports for horizontal ducts - rectangular, flat oval and circular Part Seven - General 16 Standard Abbreviations 17 18 19 20 21 22 23 24 25 Part Eight - Appendices Air Leakage Rates Recommended duct identification colours Examples of further identification symbols Ductwork galvanized after manufacture rectangular Compositions of the commonly used Stainless Steel grades Rectangular aluminium ducts low pressure constructional requirements Circular aluminium ducts low pressure constructional requirements Zinc coating mass (weight) Access requirements for inspection, servicing and cleaning 13 18 1-8 10-12 19 24 31 32-38 39-45 Part Four - Circular Ducts Spiral and straight seams Cross joints spirally wound ducts Cross joints straight seamed ducts 29 30-31 32-33 53-58 59-63 Part Five - Flat Oval Ducts Cross joints spirally wound ducts Cross joints straight seamed ducts 39-40 41-42 Part Six - Hangers and Supports Horizontal ducts bearers and hangers Vertical ducts supports 45-46 46 64-75 27 28 28 76-77 Part Seven - General Fire barrier/fire damper expansion Flexible joint connections Standard component drawings Rectangular 125-152 Standard component drawings Circular 153-167 Standard component drawings Flat Oval 168-177 Plant/equipment/miscellaneous 78-79 80 81-124 29 29 36 37 38 40 178 179 44 72-73 76 80 81 85 88 90 91 93 94 Pages Part Three - Rectangular Ducts Longitudinal Seams Illustrations of panel stiffening Flanged cross joints Socket and spigot cross joints Stiffeners Tie rod assembly Hard and Easy bends Turning Vanes 19 List of Illustrations Figs 13-17 18-24 25-28 29 30 20 20 21 Part Eight - Appendices Permitted leakage at various pressures Example of duct identification symbol 22 23 24 25 25 50 52 55-61 62-67 68-70 71 78 81 Notes In this document: (1) Even where a ductwork job specification calls for the system to be wholly in accordance with DW/144, it will still be necessary for the designer, in addition to providing drawings showing details and dimensions of the ductwork, to identify specific requirements, particular to his or her design The technical information to be provided by the designer is therefore set out in detail on page 11 (2) All dimensions quoted in this specification refer to the nominal sizes, which are subject to the normal relevant commercial and published tolerances (3) Manufacturing techniques are continually subject to change and improvements and in respect of proprietary methods and devices this specification does not preclude their use if they can be demonstrated to the designer to be equally satisfactory Where there is divergence between the requirements of DW/144 and the manufacturer’s recommendations for proprietary methods and devices, the latter shall take precedence (4) The expressions ‘low-pressure,’ ‘medium-pressure’ and ‘highpressure’ relate to the pressure/velocity classes set out in Table (5) ‘Mean air velocity’ means the design volume flow rate related to the cross-sectional area (6) Reference to the air distribution system pressure relate to the static pressure of the relevant part of the ductwork system and not to the fan static pressure (7) The symbol for litres is ‘L’: 1000 litres per second is equivalent to cubic metre per second (8) The Pascal (Pa) is the internationally agreed unit of pressure The relationship of the Pascal to other units of pressure is: 500 pascals = 500 Newtons per square metre = millibars = approximately inches water gauge (9) Duct pressure classification As the static pressure in a duct system progressively changes from the fan, economic advantage can be obtained by changing the duct pressure classification to match more closely the duct distribution static pressure For example, some large systems could well be classified for leakage limits as follows: Plant rooms and risers Class C Main floor distribution Class B Low-pressure outlets Class A 10 Part One – Technical information to be provided by the designer to the ductwork contractor INTRODUCTION The selection of constructional methods is the decision of the Manufacturer to conform with the performance requirements of the specified ductwork classification Sections 2-4 below define the information that is to be provided by the Designer 4.2 Protective finishes (Section 27) Details and specification of any finishes STANDARDS 4.4 Internal thermal/acoustic lining (Section 29) The extent of any ductwork requiring internal acoustic/thermal lining is to be clearly identified A detailed specification of materials and method of application is required The practical aspects of cleaning or maintenance must be addressed by the designer before deciding to internally line ductwork 2.1 2.2 2.3 2.4 2.5 4.3 Fire rated and smoke extract ductwork (Appendix D) The extent and limits of protection for any fire resisting ductwork Pressure classification (Table 1) Leakage classification (Table 1) Positive and Negative pressures (Table 1) Materials (Section 7) Any special system requirements COMPONENTS 3.1 Inspection/servicing access openings (Section 20 and Appendix M) Number and location of all panels and covers for inspection and/or servicing access other than those covered in Section 20 and summarised as Level requirements in table 25 of Appendix M Number and location of test holes, instrument connections and hinged doors as defined in Section 20 4.5 External thermal/acoustic insulation (Section 30) The extent and thickness of insulation to be provided by others should be stated 4.6 Special supports (Section 19) Details of any spanning steel or special support requirements not covered by Section 19 4.7 Attachment to building structure (Section 28) Specific requirements for the junction of ductwork and associated components to openings should be detailed and specified and the limits of responsibility defined 3.2 Cleaning access (Section 20.8 and Appendix M) Designers shall stipulate their requirements for periodic internal cleaning of ductwork and for the consequent need for adequate access for specialist cleaning equipment The provision of penetrations and associated framings are outside the scope of this specification 3.3 Regulating dampers (Section 21) Specification, location and mode of operation of all regulating dampers 4.8 Air terminal units Detail and specifications of all Air Terminal Units It is expected that all Air Terminal Units and their Plenums (See Figures 120 to 124) will be supported by the Ceiling Grids unless the designer indicates an independent method of support 3.4 Fire dampers (Section 22) Specification and location of all fire dampers to meet the requirements of the Authority directly concerned with fire protection 3.5 Smoke dampers (Section 23)/Combination smoke and fire dampers (Section 24) Specification and location of all smoke dampers to meet the requirements of the Authority directly concerned with fire protection 3.6 Flexible ducts (Section 25) Specification and location of ductwork any protective 4.9 Ductwork layout drawings Details of any special requirements relating to CAD, scales, etc It is common practice and cost effective for ductwork manufacturers to utilise their approved ductwork layout drawings as a basis of their manufacturing/installation information by adding the necessary details to the same drawing Scales of 1:50 or smaller may preclude this practice, therefore, larger scales might be more appropriate The final choice of manufacturing/installation scales shall be left to the ductwork contractor flexible 3.7 Flexible joint connections (Section 26) Specification and location of any flexible connections eg plant or building expansion joints PARTICULAR REQUIREMENTS 4.1 Air leakage testing (Section and Appendix A) The extent of any air leakage testing While it shall be mandatory for high-pressure ductwork (as defined in this specification) to be tested for air leakage in accordance with the procedure set out in DW/143, A practical guide to Ductwork Leakage Testing, no such testing of low- or medium-pressure ductwork is required 4.10 Other requirements Details of any requirements for the ductwork not in accordance with the provisions of this specification, including any modified construction required to conform with any requirements concerning external ductwork (See 5.3) or to meet the regulations of a local authority or other controlling body 11 APPENDIX F – STAINLESS STEEL FOR DUCTWORK F.1 General F.1.1 Stainless steel is not a single specific material: There is a large family of stainless steels with varying compositions to suit specific applications, but all contain at least 11% of chromium as an alloying addition usually adjusted by the manufacturer to balance forming response, weldability and corrosion resistance It is readily welded in thin sheet form and, since it does not form a hardened weld HAZ, no post-weld heat treatment is required It is widely used for automotive exhaust system parts and is suitable for a range of ducting and structural applications in mildly corrosive applications F.1.2 Modern stainless steels have a combination of good formability and weldability, and can be supplied with a variety of surface finishes (see F.4.1 below) They have been developed to cover a wide range of structural uses where high resistance to corrosion and low maintenance costs are demanded F.2.2.2 17% chromium ferritic steel, 430S17, New Designation 1.4016, x6Cr17 Forming and general characteristics are similar to the 409 grade, but the higher chromium level confers better general corrosion resistance F.1.3 Ductwork applications for which stainless steels are particularly suited include those where a high integrity inert material is essential; where a high degree of hygiene is required; in the chemical industries where toxic or hazardous materials may be contained; in nuclear and marine applications (e.g on offshore platforms) Stainless steels also find application in exposed ductwork where their finish can be used to aesthetic advantage F.2.2.3 18% chromium, 9% nickel austenitic stainless steels A widely used grade is 304S15, New Designation 1.4301, x5CrNi18-10 There are compositional variants within this family, designed to give specific formability and welding characteristics All are weldable and have good general corrosion resistance to normal and mildly corrosive atmospheres They are ductile and formable, but forming loads are higher than for mild steels and suitable, robust equipment is required F.2 Grades of stainless steel F.2.1 The grades of stainless steel most commonly used for ductwork applications are among those covered currently by BS 1449, Part However, a European Standard, will supersede this British Standard New designations of the most common steel grades are given in Table 21 F.2.2.4 17% chromium, 11% nickel, 2% molybdenum austenitic steel, a widely used grade of this type is 316S31, New Designation 1.4401, x5CrNiMo17-11-2 In some cases there are minor differences in chemical composition between the BS and EN grades This steel has a significantly higher corrosion resistance than the standard 18% chromium, 9% nickel steels and is suitable for use in more aggressive environments such as are met in ductwork in process plants However, more highly alloyed stainless steels with better corrosion resistance are also available and the advice concerning aggressive environments given under section F.2.1 above should be noted Before a grade is specified, the nature of the interior and exterior environments of the ductwork system should be taken into account The steels described below cover most normal applications However, advice on specific corrosion risks should be taken if the ductwork is to be installed in a chemically contaminated atmosphere, or is to be used to transport contaminated air, particularly if there is a risk of internal condensation More highly alloyed grades of stainless steel with enhanced corrosion resistance are available if required F.3 Availability Stainless steel is supplied in a wide range of thicknesses, from 0.4 mm for cold-rolled sheet and coil, and from 0.075 mm for precision rolled strip It is supplied in slit widths as specified by the customer, up to a maximum width of 2030 mm, depending on thickness The commonly used steels divide into two main families; the lower alloy ferritic 11-18% chromium stainless steels are magnetic The austenitic, 18% chromium, 9% nickel steels have generally better corrosion resistance and are non- or only slightly magnetic Material compatability of sheet, section and fixings is not always assured in practice due to commercial availability F.2.2 The more commonly used stainless steels and their characteristics are described below F.4 Surface finishes F.4.1 Stainless steel is available in a wide selection of finishes, varying from fine matt to mirror polished, as defined in BS 1449: Part 2: and in EN10088: Part F.2.2.1 11.5% chromium ferritic steel with a titanium addition, 409S19, New designation 1.4512, X2CrTi12 This, and related grades, are among the leanest alloyed of the stainless steels Forming characteristics are similar to those of mild steel, so it can be worked using conventional practices The composition and processing of the steel is Mill finishes Type 2D Cold finished softened and descaled A uniform matt finish 86 Type 2B Type 2A/2R essary, however, depending on the type of stainless steel being used Cold rolled, softened, descaled and lightly worked with polished rolls A smooth finish brighter than 2D F.6.3 As a general rule, the 400 series of stainless steels can be formed using normal mild steel settings The 300 series, however, because of the higher yield point and the greater rate of work hardening, will require higher working pressures Bright annealed A cold finished reflective appearance retained through annealing F.6.4 Ductwork contractors who have experience of the use of stainless steel report difficulty in forming Pittsburgh and button punch snap lock seams As regards cross joints, socket and spigot joints are recommended, and one or two of the slide-on flanges are suitable In view of the foregoing, it is recommended that trials be carried out before starting on production Polished finishes Type 4/2J Dull polished A lustrous unidirectional finish produced by fine grinding, generally with abrasives of 150 grit size It has little specular reflectivity Further dull polishing after fabrication will diminish the effects on appearance of welds or accidental damage by blending them into the surrounding metal Type 5/2K Type 8/2P F.7 Rectangular ducts The constructional requirements for rectangular stainless steel ducts are the same as for galvanized mild steel Dull polished with specific requirements, to achieve a fine, clean cut surface finish with good corrosion resistance F.8 Circular ducts The constructional requirements for circular stainless steel ducts are the same as for galvanized mild steel Mirror polished A bright, nondirectional reflective finish with a high degree of image clarity F.9 Stiffening Wherever possible, the material used for stiffening should be of the same grade of stainless steel as used for the construction of the ducts, or should be made equally corrosion resistant to suit the environment in which the ductwork is situated F.4.2 Where other finishes are required, such as for aesthetic purposes, a range of patterned or textured (2F,2M) finishes is available Colour may be applied in the form of paint or lacquer, or the material may be supplied pre-coloured as by the ‘INCO’ process or by mill application of polymer coatings F.10 Fixings and fastenings The types of fastening and the maximum spacings specified in Table (rectangular) and Table (circular) also apply to stainless steel ductwork F.5 Surface protection F.5.1 No surface protection is required for stainless ductwork used indoors or outdoors, provided the correct quality is specified This is because the naturally occurring chromium-rich oxide film which is present on the surface of the metal, if damaged, reforms immediately by reaction between the steel and the atmospheric or other source of oxygen Fixings and fastenings should be of the appropriate grade of stainless steel as used in the construction of the ductwork, or should be made equally resistant to corrosion in relation to the environment in which the ductwork is situated The type of stainless steel fastening used should conform to the appropriate specification BS 6105: 1981 F.11 Welding All the modern welding processes may be used to weld stainless steel but carburising operations such as oxy-acetylene and carbon arc welding are not suitable The Tungsten inert gas (TIG) and resistance welding techniques are most likely to be used for thin gauge materials Attention is drawn to BS 4872: Part 1982, (welder qualification) and BS 7475: 1991 (welding processes) F.5.2 If a mixture of metals is used, such as mild steel supports for stainless steel ductwork, the surface of the mild steel must be adequately protected from the galvanic corrosion that might result from the intimate contact between the two types of metal (The appropriate protective finish should be employed See 27.3.5) F.6 Construction F.6.1 Sheet thicknesses for stainless steel ductwork should be the same as for galvanized steel (see Tables 2, and 4) Provided the correct grade of stainless steel has been selected, there is no requirement for a corrosion allowance with stainless steels and the gauge can be selected on structural considerations only Selection of the correct welding electrodes and filler rods is important, particularly when w e l d i n g d i s s i m i l a r m e t a l s , such as stainless steels to non-stainless structural steels Reference for guidance should be made to BS 2901: Part 2: 1990 for rods and wires for gas shielded welding and BS 2926:1984 for electrodes for Manual Metal Arc (MMA) welding F.6.2 The forming of rectangular and circular ducts can be carried out by the use of conventional press working and sheet metal forming machines Some alteration in working practices may be nec- F.12 Avoidance of contamination Attention is drawn to the risks of rust staining of stainless steel surfaces resulting from contamination by non-stainless steel or iron debris 87 F.13 Fire dampers Stainless steel is an ideal material for use in the construction of fire dampers, because of its high resistance both to heat and corrosion It is therefore most applicable where a fire authority specifies a requirement for corrosion resistance If particles such as filings of a non-stainless steel or iron are expressed into contact with a stainless steel, subsequent exposure to moisture will lead to staining of the surface as these particles rust Whilst this staining often can be removed without harm to the stainless steel surface, in aggressive environments corrosion products around the rust centre can create a risk of pitting of the stainless steel As a general rule, stainless steels should be kept free from iron dust and debris contamination In particular, wire brushes must be made of stainless steel and shot, beads and abrasive media used to clean surfaces must be ‘iron free’ F.14 Sealants, gaskets and tapes The sealing materials and methods set out in this publication are also applicable to stainless steel ductwork However, any chloride-based material, such as polyvinyl chloride (PVC), should be avoided, as breakdown of such material at certain elevated temperatures could lead to corrosion of the stainless steel Contamination can arise from tools which have been used previously for cutting non-stainless steels without adequate cleaning and from abrasion on stillages and racks It is good practice to dedicate storage and bench areas for stainless steels, with soft surfaces, e.g wooden battens, to mininise scratching of the surface and if practicable designate stainless only working areas F.15 General design considerations It is the designer’s responsibility to indicate the type of stainless steel most suitable for the conditions to which the ductwork is to be exposed If users and designers are in doubt as to which material is appropriate to a particular application, technical advice may be obtained from the source noted below Table 21, showing the approximate correspondence between the chemical compositions of the commonly used stainless steel grades in BS 1449, Part 2: 1983, and the European Standard EN 10088-1, List of Stainless Steels (Part gives the chemical compositions and identifications of the stainless steels, it is for information Part of this standard describes the technical delivery conditions for sheet/plate and strip for general purposes.) Grade Designation, Grade Name and Fit on chemical composition BS 1449 pt 2: 1983 Number in EN10088-1 between standards 409S19 x2CrTi12 1.4512 430S17 x6Cr17 1.4016 304S15, x5CrNi18-10 1.4301 wider close fit wider close fit 304S16 304S31 x2CrNi18-09 1.4307 wider x2CrNi19-11 1.4306 wider 316S11 x2CrNiMo17-12-2 1.4404 close fit 316S31 x5CrNiMo17-12-2 1.4401 close fit 304S11 This appendix is based largely on information kindly supplied by the Avesta Sheffield Technical Advisory Centre, ASTAC, P.O Box 161, Shepcote Lane, Sheffield S9 1TR Telephone: 0114 244 0060 Fax: 0114-242 0162 88 APPENDIX G - PRE-COATED STEEL G.5 Ductwork construction from pre-coated steel G.5.1 The type of pre-coated steel most suitable for ductwork should be carefully considered, mainly from the point of view of the fabrication properties of the coating type It is probable that a plastisol coating will be found to be most suitable for ductwork, as this type of coating will withstand forming at normal ambient temperatures It also tolerates rougher handling during forming and erection than the much thinner paint coating types G.1 Nature of the material G.1.1 ‘Pre-coated’ steel is sheet, coil or strip to which has been applied at the steel mills a coating having a decorative or protective function, or both G.1.2 The basis metal to which the coatings are applied are hot-dip galvanized or aluminium-zinc coated sheet or coil, uncoated steel or electrogalvanized steel (e.g., Zintec) G.2 Range of coatings available G.2.1 A number of different types of coating, in various thicknesses, are available – PVC (‘Plastisol’ and ‘Organosol’); paint coatings of several types, silicone enamels, etc G.5.2 Careful consideration should be given to the constructional methods to be used for ductwork to be made from pre-coated steel The principle to be followed should be to make seams and joints as unobtrusive as possible Some of the conventional methods of seaming may be used, but a number of others are not suitable Welding with conventional equipment should not be attempted Mechanical fastenings should be chosen with care having regard to appearance as well as efficiency; and sealant should be applied with these factors in mind Stiffening should be carefully considered in relation to appearance G.2.2 A wide range of colours and surface finishes are available, but there are minimum quantity requirements for some types of coating, finish and colour The characteristics of the particular type of coating contemplated for a particular use should be investigated in respect of formability, fastness to light, chemical resistance and other relevant properties G.2.3 The material can be supplied with one or both sides treated, with the specified coating Standard ‘backing coat’ finishes are usually applied to the reverse side unless otherwise stated G.6 Handling, storage, transport and erection G.6.1 Much more care than usual is required in these respects, as the coatings are all to a greater or lesser degree susceptible to mechanical damage For example, sheet should not be dragged off the top of a pile but removed by ‘turning’ off the stack G.3 Sizes available G.3.1 Pre-coated steel is available in sheet or coil form The maximum available width can vary according to the steel thickness required Availability varies according to type of substrate and coating, so prospective purchasers should query the sizes available for the specific type required G.6.2 With sheet pre-coated on one side only, it may be found desirable to stack face to face G.6.3 The flexibility of coatings of the types used on pre-coated steel depends on temperature Therefore, manipulation should be carried out at temperatures above 16°C (60°F) in order to minimise the risk of the film cracking on roll forming, etc If the material has been stored outside at low temperature, a warm-up period should be allowed before manipulation of the sheet is undertaken G.4 Sources of supply G.4.1 Pre-coated steel is widely available but it should be noted that minimum order quantities may apply The information on which this appendix is based has been kindly supplied mainly by British Steel plc More detailed information may be obtained from: British Steel plc, Product Development Centre, Shotton Works, Deeside, Flints CH5 2NH Telephone: Chester (01244) 812345 Fax: 01244 836134 89 APPENDIX H – ALUMINIUM DUCTWORK H.5 Fastenings H.5.1 The types of fastening and the maximum spacings specified in Table (rectangular) and Table (circular) apply to aluminium ductwork, except that such fastenings shall be of aluminium, stainless steel or monel metal H.1 Scope This section applies only to rectangular and circular aluminium ductwork operating at low pressure, as defined in Tables 22 and 23 If consideration is being given to either higher pressures or flat oval ductwork then it would be prudent to seek advice from manufacturers who have the experience and capacity to manufacture aluminium ductwork H.6 Welding H.6.1 All the aluminium alloys can be welded by MIG (Metal and Inert Gas) or TIG (Tungsten and Inert Gas) methods, with argon as the shielding gas Helium or a mixture of helium and argon can be used, but not C0 Alloys in a work-hardened temper are reduced to the annealed condition in the heat affected zone; 6082-T6 is reduced approximately from the T6 to the T4 temper Alloys 1200 and 3103 are easy to braze, as is 6082, but the latter needs to be re-heat treated to regain its strength H.2 Suitable grades H.2.1 Ductwork can be constructed from all the commonly used aluminium alloys, the choice depending on the purpose for which the ducts will be used and the service environment H.2.2 The alloys 1200, 3103 and 5251 (as specified in BS.EN485, BS.EN515, BS.EN573) are easy to form and to join, and have excellent resistance to atmospheric corrosion, with 5251 being rather more resistant to marine atmospheres H.7 Protective finishes H.7.1 No protective finishes are required for aluminium ductwork used indoors or outdoors in normal atmospheric conditions In moist atmospheres, particularly if they are contaminated by industrial effluent or by salt from the sea, surfaces not exposed to washing by rain will become roughened and covered with a layer of white corrosion product However, this has the effect of sealing the surface against further attack, and the mechanical properties of any but the thinnest of materials will be only slightly affected H.2.3 These alloys can be supplied in various tempers produced by different degrees of cold rolling, so that a range of strengths is available In choosing a temper, it is necessary to consider any forming that will be done, as with the harder tempers the forming of tight bends might cause cracking Where high strength is required, alloy 6082-T6 sheet can be used H.2.4 Aluminium coil is available in plain form and pre-painted finish H.7.2 If surface protection is specified, any of the normal organic finishes can be used, including the laminated PVC films, although paints with heavy metal pigments are not suitable The use of prepainted strip in coil form provides a reliable quality finish and often proves more economical than painting after assembly Anodising provides an excellent finish for aluminium, but this process would have to be carried out after forming and would therefore not usually be practicable for ductwork, except perhaps for ducts formed from extrusions H.3 Construction – rectangular ducts H.3.1 Table 22 sets out the minimum constructional and stiffening requirements for rectangular aluminium ducts and the permitted types of cross joint H.3.2 Sealant The sealant requirements set out in this specification for galvanized steel rectangular ductwork also apply to the longitudinal seams and cross joints in aluminium ductwork H.4 Construction - circular ducts H.4.1 Table 23 sets out the minimum constructional and stiffening requirements for circular ducts made from aluminium, and the permitted types of cross joint Table 22 H Mild steel section used in supporting aluminium ductwork shall have a protective finish (See 27.3.5) Rectangular aluminium ducts – low pressure constructional requirements Maximum duct size (longer side) Minimum sheet thickness Maximum spacing between joints/stiffeners Suitable cross-joints Plain sheet With cross breaking or pleating mm – Minimum aluminium angle section for cross-joints and stiffeners mm 400 mm 0.8 Figs 13, 14 mm – 600 0.8 10 - 12, 15 - 17 1500 – 25 x 25 x 800 1.0 10 - 12, 15 - 17 1200 1500 30 x 30 x 1000 1.0 10 - 12, 15 - 17 800 1200 40 x 40 x 1500 1.2 10 - 12, 15 - 17 600 800 40 x 40 x 2250 1.2 10, 11 600 800 50 x 50 x 3000 1.6 10, 11 600 600 60 x 60 x 90 mm – Table 23 Circular aluminium ducts (spirally-wound and straight-seamed) – low pressure constructional requirements Straight-seamed duct Spiral-wound duct Normal sheet thickness as for galvanised duct Table Cross joints figs 32 - 38 with LP Limits Minimum stiffening requirements as for galvanised duct Table Normal sheet thickness Cross joints figs 39 - 45 with LP limits as for galvanised duct Table Col Minimum stiffening requirements Minimum aluminium angle section for cross joints and stiffeners Duct diameter angle mm mm as for galvanised duct Table 800 25 x 25 x 1000 30 x 30 x 1500 40 x 40 x Incorporates information provided by the Aluminium Federation Ltd., Broadway House, Calthorpe Road, Five Ways, Birmingham B15 1TN (telephone: 0121-456 1103) from whom more detailed information may be obtained APPENDIX J – EUROVENT tate commercial exchanges between its nations in the search for improved quality; adoption of rules, directives and codes of in the technical and economic spheres member countries’ J.1 General Some explanation of the function, composition, objectives and membership of EUROVENT is given below member and the practice in the J.2 Membership EUROVENT is an omnibus word standing for the European Committee of the Construction of Air Handling Equipment The committee was formed in 1959, and in 1977 its constituent members were the relevant national associations in Austria, Belgium, Denmark, Finland, France, German Federal Republic, Italy, Netherlands, Norway, Sweden, Switzerland and the United Kingdom J.4 EUROVENT publications EUROVENT has published a number of documents in the air handling field, and these include Document 2/2 covering the procedure for testing for air leakage in ductwork, and provides for two levels of permissible air leakage for low-pressure air distribution systems Document 2/3 covers the standardisation of duct sizes J.3 Objectives The objectives of EUROVENT are ‘to improve and develop technical matters in the manufacture and operation of air handling equipment; to improve the professional status of its members and to facili- J.5 Air leakage The basis on which air leakage is calculated in EUROVENT Document 2/2 has been adopted in DW/143 A practical guide to Ductwork Leakage Testing Information about EUROVENT may be obtained from the HEVAC Association, Sterling House, Furlong Road, Bourne End, Bucks SL8 5DG (Telephone: 01628 531186 Fax: 01628 810423) 91 APPENDIX K – SUMMARY OF BS.EN10142: 1991 CONTINUOUSLY HOT-DIP ZINC COATED MILD STEEL STRIP AND SHEET FOR COLD FORMING Normal spangle (N) This finish is obtained when the zinc coating is left to solidify normally Either no spangle or zinc crystals of different sizes and brightness appear depending on the galvanizing conditions The quality of the coating is not affected by this NOTE Normal spangle is the type normally supplied for a wide variety of applications Note – The extracts from BS.EN10142: 1991 have been prepared by the HVCA and are included here by courtesy of the British Standards Institution K.1 GENERAL K.1.1 The BS 2989: 1975 and 1982 entitled ‘Continuously hot-dip zinc coated and iron-zinc alloy coated steel: wide strip, sheet/plate and slit wide strip’ summarised in DW/142 has been superseded by BS.EN10142: 1991 entitled ‘Continuously hot-dip zinc coated mild steel strip and sheet for cold forming’ (including amendment A1:1995) Minimized spangle (M) The surface has minimized spangles obtained by influencing the solidification process in a specific way The finish may be specified if the normal spangle applicable does not satisfy the surface appearance requirements K.1.2 British Standard BS.EN10142: 1991 sets out requirements for the conventional galvanized sheet and coil and for zinc-iron coated steel (Both these are included in DW/144 - see Section 7.) K.5 SURFACE PROTECTION K.5.1 General Hot-dip zinc coated strip and sheet products generally receive surface protection at the producer’s plant The period of protection afforded depends on the atmospheric conditions The type of steel normally used for ductwork is DX51D and Z275 K.2 STEEL GRADES K.2.1 BS.EN10142: 1991 and amendment A1: 1995 lists the grades of steel set out in the next column, among others: Grade DX51D + Z DX52D + Z DX53D + Z DX54D + Z K.5.2 Chemical Passivation Chemical Passivation protects the surface against humidity and reduces the risk of formation of ‘white rust’ during transportation and storage Local discolouring as a result of this treatment is permissible and does not impair the quality Name of grade Bending and profiling quality Application Forming quality steel suitable for manufacture of the most profiles and more difficult bending operations Drawing quality Forming quality steel suitable for simple drawing operations and for more difficult profiling operations Deep drawing Forming quality quality steel suitable for deep drawing and difficult forming operations Special deep Forming quality drawing quality steel suitable for deep drawing and difficult forming operations where a non-ageing steel is required K.5.3 Oiling This treatment also reduces the risk of corrosion of the surface It shall be possible to remove the oil layer with a suitable degreasing solvent which does not adversely affect the zinc K.5.4 Chemical Passivation and Oiling Agreement may be reached with the producer on this combination of surface treatment if increased protection against the formation of ‘white rust’ is required K.5.5 Untreated Hot-dip zinc coated strip and sheet products complying with the requirements of this standard are only supplied without surface protection if expressly desired by the purchaser on his own responsibility In this case, there is increased risk of corrosion K.6 FORMING K.6.1 The British Standard says that provided that the profiling machine is set to avoid excessive stretching in the product, it is possible to form lock seams successfully with DX51D + Z sheet up to a thickness of 1.5 mm and DX52D + Z sheet up to mm; and snap lock seams with DX51D + Z up to 0.9 mm thick sheet and DX52D + Z sheet up to mm K.3 COATING TYPES AND TOLERANCES K.3.1 The types of zinc coating are set out in Table 24 BS.EN10142: 1991 (reproduced at the foot of this summary) K.3.2 Whilst the coating thickness is not subject to tolerances the substrate and consequently the gauge thickness does have accepted tolerances and these including sheet widths/lengths will be found in BS.EN10143: 1991 K.7 WELDING K.7.1 Care should be taken to use proper methods and procedures The iron-zinc coating is more suitable for resistance welding than the conventional zinc coating K.4 COATING FINISHES K.4.1 BS.EN10142: 1991 and A1 1995 includes a description of the various types of finish available: 92 Table 24 (Extract from BS.EN10142: 1991) Coating mass (weight) Minimum coating mass (including both sides Suggested applications (see note 2) Coating designation Triple spot test Single spot test g/m2 g/m2 Z100 Z200 100 200 85 170 Light – for use where corrosion conditions are not severe and/or where forming operations preclude heavier coatings Z275 275 235 Standard Z350 Z450 Z600 350 450 600 300 385 510 Heavy duty – for longer life relative to Heavy duty – standard and light coatings 100 180 85 150 Iron-zinc alloys – alloyed coatings of iron and zinc for easy painting and particularly resistance welding Zinc coatings (Z) Zinc-Iron alloy coatings (ZF) ZF100 ZF180 Note The mass of zinc is not always equally distributed on both surfaces of the sheet However, it can normally be expected that not less than 40% of the specified minimum coating mass, as determined by the single spot test, will be found on each surface Note The suggested applications included in the right-hand column of the above table are those provided by British Steel PLC APPENDIX L – ‘DESIGN NOTES FOR DUCTWORK’ (CIBSE Technical Memorandum No 8) Standard dimensions of circular, rectangular and flat oval ducts L.1 At the time of publication (1983) this technical memorandum brought together information on the design of ductwork systems Duct sizing methods, including velocity, equalfriction and static regain methods, and pressure loss calculations, with an example calculation L.2 The contents had been drawn from the relevant sections of the CIBSE Guide and other recognised references, and include additional material on good design practice The Notes make frequent reference to DW/142, and an effort was made to ensure consistency between the two publications Whilst DW/142 has now been superceded by DW/144, the technical memorandum, has not currently been up-dated but still contains relevant information that may be of use to a ductwork designer/manufacturer Whilst some of the information may now be superceded, TM8 includes chapters on: Heat loss from and gain to air in the duct; condensation, noise control and fire Commissioning and testing Overseas work Drawing symbols in current use L.3 The flow of heavily contaminated air in ducts is not covered in detail in the Notes; nor are the constructional aspects of ductwork, which are dealt with in DW/144 Pressure loss in ducts, including corrections for duct surface type, air pressure, air density, temperature and altitude, and loss factors for fittings Equivalent diameters of rectangular and flat oval ducts L.4 The Notes were completed by references, a bibliography of over thirty titles and appendices covering properties of air, ductwork support loads, velocity pressure for air flow and conversion to SI units Technical Memorandum No was published by the Chartered Institution of Building Services Engineers, Delta House, 222 Balham High Road, London SW12 9BS (Telephone: 0181 675 5211) and whilst it is no longer available as a publication, it is still available in photo-copy form 93 to be fitted as close as practically possible to the ‘obstruction’ and then at 10 metre intervals from that point until the next internal ‘obstruction’ occurs APPENDIX M (Revised) Guidance notes for inspection, servicing and cleaning access openings NOTE! Kitchen extract systems, with panels at metre intervals, and vertical ductwork, with a panel at the bottom and top of each riser, are the only exceptions to panels behg at 10 metre intervals b) M.1 General This appendix highhghts, in summary form, the access considerations that should be made by the designer in terms of inspection, servicing and cleaning Having considered the scope and the design of the ductwork system relative to the guidelines outlined below, the designer should clearly indicate the access requirements that are to be incorporated into the manufacture of a new ductwork system M.2 The minimum requirements in (a) and (b), if specified by the designer, negates the requirement for panels to be provided at ‘changes of direction’ in the ductwork system i.e bends, branches, etc, and which not constitute an ‘obstruction’ in terms of the definition referred to in (a) previously Design Considerations M.2.1 Inspection and servicing requirements are ‘set out in Section 20 of this specification M.2.2 Care, protection and standards of cleanliness prior to commissioning are set out in the HVCA publication D W ; m “Guide to Good Practice, Internal Cleanliness of New Ductwork Installations” and the guide states ‘Where specific levels of cleanliness are required, ductwork shall be cleaned after installation by a specialist cleaning contractor” M.2.3 It will be in the interests of the designer, both financially and practically, to consider employing a specialist cleaning contractor at the outset of a contract to internally clekn newly installed duckork prior to hand-over This approach would realise the following benefits:i) The actual number of cleaning access panels could be determined to suit the method of cleaning to be adopted ii) As a result of the involvement of a specialist clean ing contractor, clear,directionscould be given to the ductwork contractor as to the size and location of cleaning access panels that &e required to be fitted during the manufacturing process iii) A specialist cleaning operation prior tocommissioning would enable the cleaning contra& tor to venfy the practical access requirements for the future cleaning operations associated with a regular maintenance progapme iv) A specialist c l e e g operation prior to commissioning would allow the designer to omit from the specification the DW/TM2 requirements for factory sealing, protection, wipe downs and capping-off M.2.4 In the absence, at the ductwork manufacturing stage, of any access panel size and location input from a specialist cleaning contractor @en the designer may consider that the following minimum requirements should be incorporated into a new ductwork system:a) -4naccess panel, of specified size, should be fitted upstream of any internal ‘obstruction’ i.e splitters, airturns,blades, pods, coils, filters, etc The panel is The designer should identify any ‘obstruction’ or item of equipment that requires an access panel on both the upstream and downstream side duct connections with the upstream panel being used as the start point measure for any subsequent panels as referred to in (a) previously M.2.5 Careful consideration must be given by the designer to the practical problems associated with the manufacture and fitting of suitably sized access panels on both small cross section rectangular ducts and the circular faces of round and flat oval ducts and the ductwork manufacturer should be instructed accordingly M.2.6 Cleaning requirements for both new and existing ventilation systems are set out in the HVCA publication W , “Guide to Good Practice, Cleanliness of Ventilation Systems” The guide establishes standards for testing, cleaning and verification and provides greater detail for the designer’s consideration than the basic information included in this appendix The guide also includes the statement; “The precise location, size and type of access would be dependent on the type of ductwork cleaning, inspection and testing methods to be adopted” I NOTE! In the absence of any indication by the designer for cleaning requirements, only thc access panels for inspection and servicing set out in Section 20 of this specification will be incorporated into a new ductwork system M.2.7 Special consideration must be given by the designer to the practical problems associated with gaining personnel access to heavily congested ceiling areas and multi-layered ductwork systems Such consideration would avoid the possibility of access panels being incorporated into a ductwork system at the manufacturing stage that were later found to be inaccessible for either servicing or cleaning activities M.3 Access to in-line equipment M.3.1 This appendix only covers access/inspection through the ductwork body adjacent to an item of in-line equipment and not openings in the equipment itself Appendix M (Revised) June 2002 APPENDIX M – GUIDANCE NOTES FOR INSPECTION, SERVICING AND CLEANING ACCESS OPENINGS M.1 GENERAL This appendix highlights, in summary form, the access consideration that should be made by the designer in terms of inspection, servicing and cleaning Having considered the scope and the design of the ductwork system relative to the guidelines outlined below the designer should clearly indicate which level/s of access should be incorporated into the manufacture of a new ductwork system (See Table 25 and Note below it) M.2 DESIGN CONSIDERATIONS ii) Clear directions could be given to the ductwork contractor as to the size and location of cleaning access panels that are required to be fitted during the manufacturing process iii) The specialist cleaning operation prior to commissioning would enable the cleaning contractor to verify the practical access requirements for the future cleaning operations associated with a regular maintenance programme iv) A specialist cleaning operation prior to commissioning would allow the designer to omit from the specification the DW/TM2 requirements for factory sealing, protection, wipe downs and capping-off v) Specialist cleaning to the measurable standards defined in TR17 will allow an objective definition of cleanliness to be achieved M.2.1 Inspection and servicing requirements are set out in Section 20 of this specification M.2.2 Cleaning requirements are set out in the HVCA publication TR17 “Guide to Good Practice, Cleanliness of Ventilation Systems” and the guide states “The precise location, size and type of access would be dependent on the type of ductwork cleaning, inspection and testing methods to be adopted.” Careful consideration must be given by the designer to the practical problems associated with the manufacture and fitting of suitably sized access panels on small cross section ducts and the circular faces of round and flat oval ducts in particular Care, protection and standards of cleanliness prior to commissioning are set out in the HVCA publication DW/TM2 “Guide to Good Practice, Internal Cleanliness of New Ductwork Installations” and the guide states “Where specific limits of cleanliness are required, ductwork shall be cleaned after installation by a specialist cleaning contractor.” M.2.3 Special consideration must be given by the designer to the practical problems associated with gaining personnel access to heavily congested ceiling areas and multi-layered ductwork systems This approach would avoid the possibility of access panels being incorporated into a ductwork system at the manufacturing stage that were later found in practice to be inaccessible for either servicing or cleaning activities It will be in the interests of the designer, both financially and practically, to consider employing a specialist cleaning contractor at the outset of a contract to internally clean newly installed ductwork prior to handover This approach would realise the following benefits:- M.3 ACCESS TO IN-LINE EQUIPMENT The actual number of cleaning access panels could be determined to suit the method of cleaning to be adopted (This may be less than the maximum requirements listed under Level of Table 25) i) This appendix only covers access/inspection through the ductwork body adjacent to an item of in-line equipment and not openings in the equipment itself Table 25 Access requirements for inspection, servicing and cleaning HVCA PUBLICATION REFERENCE Adjacent in-line items/equipment Guide to Good Practice Cleanliness of Ventilation Systems DW/144 Inspection/Servicing Section ref 20.1.1 Control Dampers Fire Dampers Heating/Cooling Coils Attenuators (rectangular) Attenuators (circular) Filter Sections Air Turn Vanes Changes of Direction In-Duct Fans/Devices Notes Level Level Cleaning Survey/Inspection Panels (minimum size subject to duct size) Cleaning Access Panels Level One (inspection) One (servicing) One (inspection) None required None required One (inspection) None required None required One (inspection) One 300mm x One 300mm x One 300mm x One 300mm x One 300mm x None required None required None required None required 20.3 20.2.1.1 20.2.1.3 20.2.1.2 20.2.1.3 200mm 200mm 200mm (upstream) 200mm (downstream) 200mm (downstream) Both sides One side Both sides Both sides One side Both sides Both sides One side Both sides In the absence of any indication by the designer only Level access will be incorporated into a new ductwork system The panel sizes associated with Level/s and access are established by reference to Section 20 of DW/144 and Section of TR17 respectively 94 APPENDIX N – BIBLIOGRAPHY Included in this Bibliography are technical publications which may be of interest to ductwork designers fabricators and erectors, and to those in the heating, ventilating, air conditioning industries generally Enquiries should be made of the relevant organisation, at the address quoted Since its publication other addresses contained within DW/144 may have changed, and some publications may have been superseded Research Reports Ventilation system hygiene — A review of RR01/95: published information on the occurrence and effects of contamination HEATING AND VENTILATING CONTRACTORS’ ASSOCIATION 34 Palace Court, London W2 4JG Telephone: 0171-229 2488; Fax: 0171-727 9268 NATIONAL ENGINEERING SPECIFICATION LIMITED Southgate Chambers, 37/39 Southgate Street, Winchester SO23 9EH (Telephone: 01962 842058; Fax: 01962 868982) Orders to HVCA Publications, Old Mansion House, Eamont Bridge, Penrith Cumbria CA10 2BX (Telephone: 01768 864771 Fax: 01768 867138) Email: hvcapublications@hvwelfare.co.uk DW/144 Specification for sheet metal ductwork (low-, medium- and high-pressure) (1998) DW/143 A practical guide to ductwork leakage testing (1983) Specification for plastics ductwork Guide to good Practice for kitchen ventilation systems Guide to good practice glass fibre ductwork Acceptance scheme for new products — Rectangular cross joint classification Guide to good practice — Internal cleanliness of new ductwork installations Guide to good practice for the design for the Installation of fire and smoke dampers DW/151 DW/171 DW/191 DW/TM1 DW/TM2 DW/TM3 Tool box talks JS5 Welding Safety booklet JS19 Safety facts edition JS21 COSHH manual volume Advice on compliance with the regulations JS 21A COSHH manual volume Assessment sheets JS23 Risk management manual TR/3 Brazing and bronze welding of copper pipework and sheet (1976) TR5 Welding of carbon steel pipework (1980) TR6 Guide to Good Practice for Site Pressure Testing of Pipework (1980) Guide to good practice cleanliness of ventilation systems TR17 booklet Fact sheets 1-24 Influence of HVAC on smoke detectors Application Guides AG.1/74 Designing Variable Volume Systems for Room Air Movement AG.1/91 Commissioning of VAV Systems in Buildings TN.6/94 Fire Dampers LB.65/94 Ventilation of Kitchens AG.3/89 The Commissioning of Air Systems in Buildings AH.2/92 Commissioning of Bems - A Code of Practice TN.24/71 Fire Dampers in Ventilating Ducts HEATING, VENTILATING AND AIR CONDITIONING MANUFACTURERS ASSOCIATION (HEVAC) Sterling House, Furlong Road, Bourne End, Bucks SL8 5DG (Telephone: 01628 531186 Fax: 01628 810423 Email: info@feta.co.uk) 2nd Publications Air Diffusion Guide Guide to Air Handling Unit Leakage Testing Guide to Good Practice: Air Handling Units Real Room Acoustic Test Procedure Specification for the Certification of Air Filters Method of Test for Water Rejection Performance of Louvres Subjected to Simulated Rainfall Test Procedure for Acoustic Louvres Specification for Floor Grilles – Types, Performance and Method of Test CHARTERED INSTITUTION OF BUILDING SERVICES ENGINEERS Delta House, 222 Balham High Road; London SW12 9BS (Telephone: 0181-675 5211 Fax: 0181-675 5449) CIBSE Volume Volume Volume Air-to-air heat recovery RR03/95: BUILDING SERVICES RESEARCH AND INFORMATION ASSOCIATION Old Bracknell Lane West, Bracknell, Berkshire RG12 4AH (Telephone: Bracknell (01344) 426511; Fax: 01344 487575) Other publications H&V safety guide 5th edition JS1 JS2 RR02/95: Specification for the Determination Efficiency of Sand Trap Louvres Domestic Mechanical Recovery Ventilation of Systems the Collection with Heat Fan Application Guide Guide A Design Data Installation and Equipment Data B C Reference Data Fan and Ductwork Installation Guide Guide to Fan Noise and Vibration Specification of Requirements for Natural Smoke and Heat Exhaust Ventilators Commissioning Codes These Codes cover the preliminary checks, setting to work and regulation of various categories of plant The Codes give a guide to design implications Air Distribution Systems Series A Boiler Plant Series B Automatic Control Systems Series C Refrigerating Systems Series R Water Distribution Systems Series W Specification Ventilators for Powered Smoke and Heat Exhaust Specification of Requirements for Smoke Curtains Design Guide of Smoke Ventilation for Single Storey Industrial Buildings Including those with Mezzanine Floors and High Racked Storage Warehouses – Issue Guidance for the Design of Smoke Ventilation Systems for Covered and Underground Car Parks – Issue Technical Memoranda Design Notes for the Middle East TM Design Notes for Ductwork TM Minimising the Risk of Legionnaires Disease TM 13 Application of Smoke Control Equipment Guide to Good Practice – Issue 95 and Systems: BRITISH STANDARDS INSTITUTION Sales Department, 101 Pentonville Road, London N1 9ND (Telephone: 0171-837 8801) BS 381C:1996 Colours (of ready-mixed paints) for specific purposes CP 413: 1973 Ducts for building services BS 476: Fire tests on building materials and structures Part4: 1984 Non-combustibility test for materials Part6: 1989 Fire propagation test for materials SHEET METAL AND AIR CONDITIONING CONTRACTORS’ NATIONAL ASSOCIATION INC (SMACNA) Headquarters: 4201 Lafayette Center Drive Chantilly Virginia 20151-1209 Mailing Address P.O Box 221230 Chantilly Virginia 20153-1230 Part7: 1993 Surface spread of flame tests for materials Part 20: 1987 Fire resistance struction Part 21:1987 Fire resistance of loadbearing elements of construction Part 22:1987 Fire resistance of non-loadbearing elements of construction Accepted Industry Practice for Industrial Duct Construction Part 23:1987 Contribution of components to the fire resistance of a structure Architectural Sheet Metal Manual (1993) elements of con- Telephone (703) 803-2980 Fax (703) 803-3732 (1975) Contractors Guide for Modification to Construction Contracts Fire resistance of ventilation ducts Part 24:1987 BS 5588 Part 9:1980 of (1993) Fire Precautions in the design and construction of buildings Ducted Electric Heat Guide for Air Handling Systems (1994) BS 729:1971 Hot dip galvanized coatings for iron and steel articles Energy Recovery Equipment & Systems (1991) BS 1449: Steel plate, sheet and strip Fire, Smoke & Radiation Damper Install Guide for HVAC Part 1:1991 Carbon steel plate, sheet and strip Systems (1992) Part 2:1983 Stainless steel plate, sheet and strip Guide to Steel Stack (1995) Energy Conservation Guidelines (1984) Fibrous Glass Duct Construction Standards (1992) HVAC Air Duct Leakage Test Manual (1985) and BS.EN10149-2: HVAC Commissioning Manual (1994) 1996 HVAC Duct Construction Standards-Metal & Flexible (1995) BS.EN 10149-3: 1996 Addendum No (Nov 1997) BS.EN 10131: 1992 BS.EN485 Parts l-4 BS.EN515 1993 HVAC Duct Systems Inspection Guide (1989) Wrought aluminium and aluminium alloys for general engineering purposes – plate, sheet and strip HVAC Systems-Application (1986) HVAC Systems-Duct Design (1990) HVAC Systems-Testing, Adjusting & Balancing (1993) BS.EN573 Parts l-4 BS 1474:1972 and Indoor Air Quality Manual (1993) Kitchen Equipment Fabrication Guidelines (1990) Wrought aluminium and aluminium alloys bars, tubes and sections Managers’ Guide for Welding (1993) Rectangular Industrial Duct Construction Standards (1980) BS.EN755 Parts 3-6 BS.EN22063: 1994 Round Industrial Duct Construction Standards (1977) Sprayed metal coatings Protection of iron and steel by aluminium and zinc against atmospheric corrosion Protection of iron and corrosion and oxidation temperatures Continuously hot-dip zinc coated mild steel strip and sheet for cold forming technical delivery conditions BS.EN10143: 1991 Continuously hot-dip zinc coated and ironzinc alloy coated steel sheet and strip tolerances on dimensions and shade BS 3533: 1981 Glossary of insulation BS.EN.ISO: 1479 relating SMACNA Master Index of Technical Publications (1995) Thermoplastic Duct (PVC) Construction Manual (1994) steel against at elevated BS.EN10142: 1991 terms Seismic Restraint Manual (1991) (w/ Appendix E, 1993) to DEPARTMENT OF THE ENVIRONMENT (Publications Centre) H.M Stationery Office, 51 Nine Elms Lane, London SW8 5DR M & E No.1 1972 Electrical installations in buildings (New Edition) M & E No.3 1988 Heating, hot and cold water, steam and M & E No.4 1970 Central heating and hot and cold water thermal gas installations for buildings Self-tapping screws and metallic drive screws installations for dwellings BS.EN.ISO: 7049: M & E No.100 1971 Mechanical ventilation for buildings 1994 BS 4800:1989 Paint colours for building purposes BS 4848: Part4: 1972 Hot rolled structural steel sections Equal and unequal angles BS 5422:1990 Specification for the use of thermal insulating materials BS 5720: 1979 Code of practice for mechanical ventilating and air conditioning in buildings BS 5970: 1992 Code of practice for thermal insulation of pipework BRITISH STEEL PLC Market Communications Dept British Steel PLC Strip Products P.O Box 10 Newport South Wales NP9 0XN (Telephone 01633 290022) (Fax 01633 464087) Publication: Edge protection by zinc 96 HEALTH AND SAFETY EXECUTIVE Rose Court Southwark Bridge London SE1 9HS ASSOCIATION FOR SPECIALIST FIRE PROTECTION Association House 235 Ash Road Aldershot Hampshire GU12 4DD Telephone 0171-717 6000 Telephone 01252 21322 01252 333901 Fax Publications Fire Rated and Smoke Outlet Ductwork: An Industry Guide to Design and Installation APPENDIX P – CONVERSION TABLES Sheet thicknesses Aluminium Galvanized steel * Standard thickness inch 0197 0236 0276 0315 0354 0394 0472 0630 0787 0984 mm 0.5 0.6 0.7 0.8 0.9 1.0 1.2 1.6 2.0 2.5 Birmingham Gauge inch BG 26 0196 24 0248 22 0312 20 0394 18 16 14 12 0495 0625 0785 0991 Standard Wire Gauge Standard thickness 0.5 mm is a standard thickness for galvanized sheet only 2.5 mm is a standard thickness for hot-rolled sheet only * See Appendix K (Section K.3) which contains information on gauge and sheet width/length tolerances 97 inch mm 0197 0.5 0236 0276 0315 0354 0394 0472 0630 0787 0984 0.6 0.7 0.8 0.9 1.0 1.2 1.6 2.0 2.5 1181 3.0 swg 26 inch 018 24 022 22 028 20 036 18 16 14 048 064 080 12 104 10 128 Some miscellaneous conversion factors Multiply by To convert To convert Multiply by Length Inches to millimetres Feet to metres 25.40 0.3048 Millimetres to inches Metres to feet 0.03937 3.281 Area Square inches to square millimetres Square feet to square metres 645.2 0.0929 Square millimetres to square inches Square metres to square feet 0.00155 10.764 Volume Cubic feet to cubic metres Cubic feet to litres Gallons (UK) to litres 0.02832 28.31 4.546 Mass Ounces to grams Pounds to kilograms Tons to tonnes Cubic metres to cubic feet Litres to cubic feet Litres to gallons (UK) 28.35 0.4536 1.016 Volume flow Cubic feet per minute to cubic metres per second Cubic feet per minute to litres per second Grams to ounces Kilograms to pounds Tonnes to tons Cubic feet Litres per 0.000472 0.4719 Motion Feet per minute to metres per second 35.315 0.0353 0.22 0.00508 0.03527 2.205 0.9842 metres per second to cubic per minute per second to cubic feet minute Metres per second to feet per minute Pressure Inches water gauge to millibars 2.491 Inches water gauge to pascals (Pa) 249.1 Pa = Newton per square metre = 10–2 millibars Standard dimensions of steel and aluminium sheet Steel (mild and galvanized) Metric mm 2000 × 2500 × 3000 × 3000 × 1000 1250 1350 1500 Equivalent 6' 8' 9' 9' ft/in / " × 3' 3 / " / 16 " × 4' 1 / " 10 / " × 4' / " 10 / " × 4' 11 / 16 " Weight of galvanized steel sheet Aluminium (commercially pure and alloy) Metric mm 2000 × 1000 2500 × 1250 3750 × 1250 Equivalent ft/in ' 3/ " × ' 3/8 " 8' 7/16 " × 4' 11/4 " 12' 5/ " × 4' 11/ " 98 Thickness Weight per square metre mm 0.5 0.6 0.7 0.8 0.9 1.0 1.2 1.6 2.0 2.5 kg 3.9213 4.7056 5.4898 6.2741 7.0584 7.8426 9.4111 12.5481 15.6852 19.6064 2119 2.119 197 Details of how to obtain further copies of this guide and other publications are available from: HVCA Publications Old Mansion House Eamont Bridge Penrith Cumbria CA10 2BX Tel: 01768 864771 Fax: 01768 867138 e-mail hvcapublications@hvwelfare.co.uk Heating and Ventilating Contractors’ Association Esca House 34 Palace Court London W2 4JG Tel: 0171-229 2488 Fax: 0171-727 9268 ... 01768 864771 Fax 01768 867138 e-mail: hvcapublications@hvwelfare.co.uk – – DW/ 131 DW/ 121 DW/ 122B DW/ 112 DW/ 132 DW/ 141 DW/ 142 DW/ l42 Previous Sheet Metal Ductwork Specifications Ductwork Specification... Ductwork Group Secretary: Gareth Keller Other Ductwork-Related Publications DW/ 143 DW/ 151 DW/ 171 DW/ 191 DW/ TM1 DW/ TM2 DW/ TM3 TR/17 A Practical Guide to Ductwork Leakage Testing Specification for... for Sheet Metal Ductwork — designated DW/ 144 — has been carried out with that objective in mind In the 16 years since the publication of its predecessor, DW/ 142 — and in the ten years since the