Heating and
Ventlilati1lng
Contractors'
Associ,ation
DW/154
e for
.~/}('rilic(/Iiofl
for Plastics Ductwork
ACKNOWLEDGEME TS
The HVCA records its appreciation and thanks to the many people and organi ations who gave advice and information during the preparation 0 f thi s specification, and in pal1icular to those members of the drafting panel who contributed tbeir time. experience and knowledge.
DW/154 DRAFTING PANEL Graham Handley (Chainnan) Me) Clarke Bemard Coates John Howes Me)vyn Sargent Keith Elphick (Drafting Panel Secretary)
Gareth Keller (Ductwork Group Secretary)
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(HVCA)
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Heating and Ventilating
Contractors' Association
Esca House 34 Palace Court
London W2 4JG
Tel: 020-7313 4900
Fax: 020~7727 9268
e-mail:
[email protected]
website.: www hvca.org.uk
First Edition 2000 © 2000 HVCA ISBN: 0-903783-31-2
1
DW/154 Specificathm for Plastics Ductwork
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Foreword PART ONE - TECHNICAL INFORMATION TO BE PROVIDED BY THE DESIGNER Introduction Standards Components Particular requirements PART TWO - STANDARDS Application Ductwork classification and Air leakage Materials Ductwork construction and Joint sealing PART THREE - RECTANGULAR DUCTS Rectangular duct sizes Co nstructio n 10.1 General 10.2 Longitudinal seams 10.3 Sheet jointing seams 10.4 Socket and spigot joints 10.5 Flanged joints 10.6 Expansion joints 10.7 Stiffeners Fittings 11.1 Standardisation of fit1ings 11 .2 Stiffeners 11.3 Split1ers 11.4 Turning vanes 11.5 Branches 11.6 Change shapes PART FOUR - CIRCULAR DUCTS Standard sizes Construction 13.1 General 13.2 Sheet jointing seams 13.3 Socket and spigot joints 13.4 Flanged joInts 13.5 Stiffeners 13.6 Expansion Joints PART FIVE - HANGERS AND SUPPORTS General PART SIX - GENERAL Access I Inspection openings Regulating dampers Fire dampers and Intumescent sleeves Flexible I Expansion joint connections Protective finishes Connections to bUilding openings Discharge / Exhaust terminal Thermal insulation Fire retardant finishes on plastic ductwork Reinforcement of ducts with GRP laminate Standard component drawings and abbreviations
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11 11 11 11 11 11 11 12 12 12 12 12 12 12 12 12
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DW/154 Spai{icatiOll for Plastics Ductwork PART SEVEN· APPENDICES ··························Appe·ndix··j.,·············A·j' r"ie'a'kage"fro'ni"ductwork ,
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Appendix 8 Appendix C Appendix D
Guidance notes for the Transport, Handling and Storage of ductwork Fire retardant finishes Guidance notes for Inspection, Servicing and Cleaning access openings Appendix E Bibliography Appendix F Conversion tables Table LIST OF TABLES ..................................................................................., PART TWO - STANDARDS Ductwork classification and Air leakage limits 1 PARTTHREE - RECTANGULAR DUCTS 2 Minimum constructional requirements - Rectangular Un-reinforced UPVC and pp Fastening centres Rectangular duct flange joints 3 PART FOUR - CIRCULAR DUCTS 4 Standard sizes Fastening centres Circular duct Flange joints 5 6 Minimum constructional requirements Circular Un-reinforced UPVC 7 Minimum constructional requirements - Circular Un-reinforced PPS and PP PART FIVE - HANGERS AND SUPPORTS Hangers and Supports - Rectangular Horizontal Ducts 8 Hangers and Supports - Circular Horizontal Ducts 9 PART SIX - GENERAL 10 Minimum constructional reguirements - Rectangular GRP Reinforced ducts 11 Minimum constructional requirements - CirCUlar GRP Reinforced ducts Standard Abbreviations 12 PART SEVEN - APPENDICES 13 Air leakage rates 14 Access requirements for inspection, servicing and cleaning LIST OF ILLUSTRATIONS ...................................................................................................... 0' •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• Fig. PART THREE - RECTANGULAR DUCTS 1-4 Cross joints 5-6 Stiffeners 7 Tie rod assembly 8 Hard and Easy bends 9 Turning vanes PART FOUR - CIRCULAR DUCTS 10-12 Cross joints Stiffeners 13 PART FIVE - HANGERS AND SUPPORTS 14-16 Support bearers 17-18 Vertical ducts supports 19-22 Arrangement of bearers and hangers PART srx - GENERAL 23-25 Expansion joints 26-28 Flexible connections 29-33 GRP reinforced - Cross joints and Stiffeners 34 Linear Thermal Expansion 35 Typical Design Stress 36-77 Standard component drawings - Rectangular 78-105 Standard component drawings - Circular 106-115 Standard component drawings - Plant/Equipment/Miscellaneous PART SEVEN - APPENDICES 116 Permitted leakage at various pressures Example of a completed test sheet
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DW/154 Specijimr;ol1 for Plastics Ductwork
ART 1 •.•..................•...•.............•...•....•........••.....
Technical information to be provided by the des·g er to the plastics ductwork cont actor 1
INTRODUCTION
1.1
Thi. specifi.calion relates to the manufa ture and installation of rectangular and circular ductwork constructed from plastics. The selection of construction method is at the discretion of the manufacturer to conform with the performance requirements of the. pecified ductwork clas ification. Sections 2-4 blow define the information to be provided by the designer.
4 4.1
STANDARDS
2.1
Pressure classification (Table 1)
2.2
Leakage classification (Table 1)
2.3
Positive and Negative pressures (Table I)
2.4
Materials (Parr 2 Section 7)
2.5
Any special ystem requirements
4.2
COMPONENTS
3.1
Access and drainage points
4.3
3.3
Regulating dampers Specification, location and mode of opel."atioll of all regulating dampers.
4.4
3.4
Flexible joint connections Sp cification and location of any flexible conne tions e.g. plant or building expansion joint.
6 ~--
and
Airflow
Pressure/velocities
Design air velocities and pressures for all main
ducts, principal branches and tenninals.
External thermal/acoustic insolation he extent and type of insulation to be provided by others should be stated, including full specification for application and installation.
4.7
Spark testing U' spark testing is required the designer shall identify land mark in the contract programme for testing to be undertaken i.e. manufactur / installation, corrunissionjng.
Air leakage testing The extent of any air leakage testing if required. While it shall be mandatory for high pres ure ductwork (a. defined in this specification) to be tested for air leakage iu accordance with the procedure set out in DW/I43, 'A Practical Guide to Ductwork Leakage Testin!2" no such te tin o of Jaw-or mediam-pres Llr duct work is requjJ·ed.
4.8
Identification Details of colour coding or identification if required. For furth r information see HVCA publication DW/l44 Appendix B.
Fire stops Stops to meet the requiremen ts of the Authority directly responsible for fire protection.
inside
Design airflow volume for all mam ducts.
branches and air tenninals.
Number and location of access doors and drainage points.
3.2
Environmental
Env ironmental conditi ons, sULToundillg tJle ductwork.
4.6
3
Plastics material
Type of plastic. material from which the
ductwork i to be manufactured, and detail of
ductwork to special requirements not within
this specification.
4.5 2
PARTICULAR REQU REMENTS
4.9
Solvent~/fomes
Details of design criteria used or adopted to avoid the trapping and discharge of liquid,. solvent fumes or gases.
DW/154 Specificatio1l for Plastics Ductwork 4.10 Protective finishes (Part 6 Section J9)
4. 7 Reference to designer In consideration of the foregoing, reference is also made to the designer in the following c1auses:
Detai Is and specification of any protective finishes.
4.11 Fire retardant finishes (Part 6 Section 23) The extent and limits of protection for any fire retardant finishes on plastic ductwork. (Specific references must be defined).
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Clause 5.2 5.3
8
12
12
12
10.6
4.12 Controls/sensing equipment Details of positions and fixing configuration of all sensors and test points to suit specialist contml and sensing equipment.
4.13 Special supports (Part 5 Section 14) Details of any spanning, primary secondary steelwork or special support requirements not specifically covered by Section 14.
4.14 Attachment to building structure (Part 6
Section 20)
Specific requirements for the junction of
ductwork and associated components to
opening hou1d be detaile.d and specified with
the limits of responsibility defined.
Tbe design and provision of penetrations and associated framings are outside the scope of this specification.
4.15 Ductwork layout drawing Details of any special requirement$ relating to CAD, scales, etc. It is common practice and cost effective for duclwork manufacturers to utilise their approved ductwork layout drawings as a basis of their manufacturing installation information by adding the necessary details to the same drawin2. Scales of 1:50 or smaller may preclude tJlis practice. therefore, larger scales might be more appropriate. The final choice of manufacturing! installation scales shall be left to the duct work contractor.
10.7.2
11.1 13.1 13.5.2
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17
13.6
17
14.1
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14.4 14.5 14.7
.19
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15.2 16.1 16.3.1 16.3.4 17.1 17.3 17.4 18.1 18.2 19.1
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21.1. 22.2
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22.3
2R
23.1 25.2 Appendix Appendix Appendix Appendix
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A B
C D
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4.16 Other requirements Details of any requirements far the ductwork not in accordance with the provisions of tbis specification including any modified construction required to conform with any requirements cancerning external ductwork (See 5.3) or to meet the regulations of a local autbority or athc:r controlling body.
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DW/154 Spaijicllliflll for Plastics Ductwork
PAR
5.4
2
This specification i ba ed on duct operating environments of not less than - 100e and for: PVC (non GRP reinforced) nor exceeding 40°C UPVC reinforced wilh GRP not exceedin cr 60 0 PPS and PP not exceeding 60° FBPP reinforced witb GRP not exceeding 70°C. Systems required to operate at temperatur outside those d tailed above, aJthough outside of Ih scop of Ll)is specification are Dot precluded but the ductwork hould be designed from fi rst principle Ilaving regard for the physical, mechanical and chemical properties of the material. It mu~t be noted that the cOlTosive re i tance of all the above m terials will decrea e at temperatures approaching 5° to looe below the parent materiaL beat distonion point. Further guidance on temperatup effect is provided in 'Fig. 34 Linear Tbennal xpansion' and 'Fig. 35 Typical 0 ign VC and PP'. Stres es for
Standards
e
5
APPLICATION
5.1
This specification sets out minimum requirem nts for tbe manufaclure and in-tallation of ductwork for commercial and industrial fume extraction and exhaust 5y terns, made from any of th material listed in Seclion 7 and being within the limit of ize and/or material Ihickness speci led in Ihe relevant tables. Normal ambient operating temperatures are assumed within the pressure/velocil. limits and the limits of air leakage for the various pressur' classes prescribed in Table 1.
5.2
Thi specill 'alion is inlended to apply to ductwork handling fume-laden air which are polluted or is otherwise exceptional in respect of temperarure or humidity (including aturated air) for dllctwork wber the external surface are exposed to a hostile environment. The design, construction. installati n supports and finishes in such case should be giv n special consideration b the de igner in relation to tbe parti '[lIar requir ments of each application.
5.3
Table
6.1
uctwork Class; icati nand
-
~
I
Low-pressure - Class A Medium-pressure - Class B High-pressure Class C
I
2 Pa
500 --1000 *2000
The leakage fa tor' u ed in able 1 for Classes
A, Band C ~u-e the ame as those for the
E
cIa. e similarly de ignated in th Document Pr E 12237/Pr::. L507.
ir Leakage Limits
Static pr sure limil
1
Compatibility with CEN
6.2
Ducl pressure class Positive
Classification and air leakage limits
Duc work la sification and air leakage limit·
are eL out in Table 1.
TIlis specification is sllitabl for ductwork expo ed to external atffio 'phere. The designer will need to ~'ive sp cift details of any special finish . /constlUction (See eetiar! J 9).
••
DUCTWORK CLASSIFICATION AND A R LEAKAGE
6
Negalive
Pa 500 750 750
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Maximum air velocity
Air I akage Limit litres per of ductwork in stacks such that access between them is of sufficient width to pennil the removal of item without interference to adjoining sta ks. Ductv.'ork components should be positioned so a to avoid crushing. Ductwork of small panel size may be stored horizontally; however care should be exercised to ensure that 'tack sizes are lim.ited 10 within the. tmctural strength of the duct sections to prevent distortion of the lower sections within t.he stack. ~
DW/154 S/1t'ci/ic(ltioll for Plastics Ductwork 8.5
Internal cleanliness of new ductwork The site storage of ductwork introduces the important cODsideration of maintaining the internal cleanliness of the ductwork. R feren e should be made to HVCA document: • DWffM2 Guide to Good Practice - internal Cleanliness of New Ductwork Installations. If the above conditioDs can not be satisfied consideration should be given by tJle designer to amending the specification to include for "Po. t Installation Cleaning' as covered by tJ1C HVCA document: • TRJ17 Guide to Good Practic - Cleanliness of Ventilation Systems.
APPE DIXC Fi e Retardant C.1
inishes
Improvement in the fire retardancy of plastic ducts can be achieved to varying degrees and is wholly dependent llPOll the surface coating laminating resin selected and construction specification adopted. In some instances smoke emission is coILSidered equaUy with other speci fication requirernen ts of the materials resistance to ignition and bumjng. It is, therefore, important for design rs to establ ish the clients' and officers detailed requirements and not rely on a tbird party interpretation of 'fire resisting or fire retardant'. Where possible the specification should refer dir etly to compliance with a British or European Standard identifying the specific sections applicable. There are various types of resin and mat rcLnforcements that can achieve a Class 1 surface spread of flame ratin o when tested according to BS476 Part 7 (1987). This test puts materials illto Class I - 4 in descending order of perfoDllance. according to the rat and extent of flame spread over their surfac under standard beating conditions. Materials should also be tested for flre propagarion to BS476 Part 6 (1989). Tbi' tesr measures the amount and rate of heat evolved by the material when subjected to standard heating
conditions. Test results are given as an index of Perfonnance (i) whicb is based on three sub indices (iJ. (i1 ). (h). The higher the value of the Index of Performance (i) the greater is the material s contribution to fire growth. The higher the value of the sub-index 0,), rhe greater the ease of ignition aod flame spread. The highest product performance classification. as defined in Approved Document B of the Building Regulat.ions. is Class O. This is acLlieved if a material surface of a composite. pl'oduct i~ either: a) composed throughout of materials of limited combustibility' or b) a Class I material which has a tlre propagation index (i) of not more than 12 and sub-index (i l ) of nor more than 6. 01' J: Class 0 is not a cla$sif1cation identified in any British Standard test. There are resin system reported to be classified to Class O. when tested to BS476 Pcl!1S 6 and 7, however designers need to ensure that such sysrems can be applied to their proposed desi.gn. In propriety resin/mat system available the fabrication techniques and COITect application are critical to the integrity of the reinforcing and clas ificatiol1. For example in some systems the u e of a non-fire retardant gelcont on a fire retardant substrate would reduce the classification. For further information see HVCA publication DW/144 Appendix D.
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DW/154 Spl'CijiClIliol1 for Plastics Ductwork
x
Guidance otes For nspect·on, Servicing a d Clean-ng Access Openings D.1
GE ERAL This appendix highlight in ummary fOI111 , the acce considerations that. hould be made by the design r iD terms of inspection, servicing and cleaning. Having considered the seop and the design of the dUCI work system relative to the guidelines outlined below the designer should clearly indicate which level/s of acces should be incorporated into the manufacture of a new duct work system (See Table 14 and Note I b low it .
D.2
DESIGN CONSIDERATIONS D.2.1 In pt::ction and servicing require ments are set out in Section 15 of Lhis specification.
D.2.2 Cleaning requirements are set out in the HVCA pubUcation TR/l7 'Guide to Good Practice, Clean Lines . of Ventilation Systems" and the guide tates 'The precise location. , ize and type of access would be dependent on the type of ductwork. cleaning inspection and te. ting metbods to b adopted: Care, protection and standards of cleanliness prior LO cOlllmi'sionin o are set out in th' AV A publication DWITM2 Guide to Good Practice, Internal Cleanliness of New Ductwork Installations" and. th guide state, 'Wh re specific limits of cleanliness are required. ductwork sball be cleaned after installation by a spcialist cleaning contractor." It will b in the interests of tht desioner, botb financially and practically. to cunsider employing a specialist c1eauing contractor at tbe
56
outset of a contract to internally clean new'ly installed ductwork prior to bandove.r. This approach would reali 'e the following benefit ': i) Tb, actual numb r of cleaning access panels could be detennined to suit the method of cleaning to be adopted (This may be 1 s than the maximum requiremen' listed under Lev 13 of Table 14). ii) Clear directions could b given to the ductwork contractor as to tJle size and location of cleaning access panels that are required to be fitted during the mauu faclunng pro s. iii) The specialist cleaning operation prior to commi . ioning \vould enable the cleaning contractor to verify the practical acee. requirement for the future cleaning operation associated \-vitb a regular maintenance programme. iv) A specialist cleaning operation prior to commissioning would allow the designer to omit from the speeilicatiolJ the DWrrM2 requirem nt for factory sealing. protection. wipe downs and capping-off. v) Specialist Ieall ill 0' to the measurable standard. defin d in TR/17 will allow an objective definition of cleanline to be achieved. Car ful consideration must be gIven by the designer to the practl aJ problems associated witb the manufacture and fitting of suitably si Led access panel on small cross section duct and on the circular faces of rouod and flat oval ducts in particular.
D.2.3 Special con ideration must be given by the de. igner to the practical problems associated with gaining personnel access to heavily congested ceiling areas and multi-la. red du 'twork systems. This approach would avoid
DW/154 Spf:ci{ication for Plastics Ductwork 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 ::;ervicing or cleaning activities.
able 14: Acce
D.3
ACCESS
0 IN-LINE EQUIPMENT
This appendix unly covers acc ,/il1spection through the ductwork body adjacent to an item of in-line equipment and not openings in the equipment itself.
requirements for inspection, servicing and cleaning HVCA PUBLICATIO
Adjace t in-line ite s/equipment Control Da pcrs Fire Dampers Heating/Cooling Coils Attenuators (rectangular) Attenuators (circular) Filter Sections Air Turn Vanes Changes of Direction In-Duct Fans/Devices
LeyeJ 1 ""pcdion/Sen lcin~
One (inspection) One (sCT\'jdJl~) One (inspedion) None required one retluired One (inspection) None requjred None required One (inspection)
REFE
NeE
(;uidt> 10 Gund Prartict
Cleanliness orVcnlillltio" S~'lcr,,~ fRjJ7
OW/144
Level 3
Level 2 Section ,d. 20.1.1
20.3 20.2.1.1 20.2.1.3
20.2.1.2
20.2.1.3
C1eaniJl\( SUn'(O)'/lnspc 'lion Palle" (minimum
\OiL\:'
