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<br />SECTION 239000 - METAL DUCTS
<br />GENERAL
<br />1.1 SUMMARY
<br />A. Section Includes:
<br />1. Rectangular ducts and fittings.
<br />2. Round ducts and fittings.
<br />3. Sheet metal materials.
<br />4. Sealants and gaskets.
<br />5. Hangers and supports.
<br />6. Seismic - restraint devices.
<br />B. Related Sections:
<br />1. Division 23 Section "Air Duct Accessories" for dampers, sound - control devices, duct - mounting
<br />access doors and panels, turning vanes, and flexible ducts.
<br />2.2 PERFORMANCE REQUIREMENTS
<br />A. Construct all ductwork to be free from vibration, chatter, objectionable pulsations and leakage under
<br />specified operating conditions.
<br />B. Use material, weight, thickness, gauge, construction and installation methods as outlined in the
<br />following SMACNA publications, unless noted otherwise:
<br />1. HVAC Duct Construction Standards, Metal and Flexible, 2nd Edition, 1995
<br />2. HVAC Air Duct Leakage Test Manual, 1 st Edition, 1985
<br />3. HVAC Systems - Duct Design, 3rd Edition, 1990
<br />4. Rectangular Industrial Duct Construction Standard, 1st Edition, 1980
<br />5. Round Industrial Duct Construction Standards, 2nd Edition, 1999
<br />6. Thermoplastic Duct (PVC) Construction Manual, 2nd Edition, 1995
<br />7. Round Industrial Duct Construction Standards, 2nd Edition, 1999
<br />8. Rectangular Industrial Duct Construction Standards, 1st Edition, 1980
<br />C. Use products which conform to NFPA 90A, possessing a flame spread rating of not over 25 and a
<br />smoke developed rating no higher than 50.
<br />3.2 SUBMITTALS
<br />A. Include manufacturer's data and /or Contractor data for the following:
<br />1. Schedule of duct systems including material of construction, gauge, pressure class, system
<br />class, method of reinforcement, joint construction, fitting construction, and support methods,
<br />all with details as appropriate.
<br />2. Duct sealant and gasket material.
<br />3. Duct liner including data on thermal conductivity, air friction correction factor, and limitation on
<br />temperature and velocity.
<br />A. Welding certificates.
<br />7.2 QUALITY ASSURANCE
<br />A. Welding Qualifications: Qualify procedures and personnel according to the following:
<br />1. AWS D1.101.1M, "Structural Welding Code - Steel," for hangers and supports.
<br />2. AWS D1.2/D1.2M, "Structural Welding Code - Aluminum," for aluminum supports.
<br />3. AWS D9.1 M /D9.1, "Sheet Metal Welding Code," for duct joint and seam welding.
<br />PRODUCTS
<br />9.2 GENERAL
<br />A. All sheet metal used for construction of duct shall be 24 gauge or heavier except for round and spiral
<br />ductwork and spiral duct take -offs 12" and below may be 26 gauge where allowed in SMACNA
<br />HVAC Duct Construction Standards, Metal and Flexible, 2nd Edition, 1995.
<br />B. Duct sizes indicated on plans are net inside dimensions; where duct liner is specified, dimensions are
<br />net, inside of liner.
<br />9.3 DUCTWORK PRESSURE CLASS
<br />A. Minimum acceptable duct pressure class, for all ductwork except transfer ductwork, is 2 inch W.G.
<br />positive or negative, depending on the application. Transfer ductwork minimum acceptable duct
<br />pressure class is 1 inch W.G. positive or negative, depending on the application. Duct system
<br />pressure classes not indicated on the drawings to be as follows:
<br />Transfer ducts 'h " -1" S.P. 1" pressure class
<br />Exhaust ducts 1%2" S.P. 2" pressure class
<br />Return ducts 1 " -2" S.P. 2" pressure class
<br />Relief ducts 1"-2" S.P. 2" pressure class
<br />Constant Volume AHU Supply 1 %2" S.P. 2" pressure class
<br />Grease Hood Exhaust 2 %3" S.P. 3" pressure class
<br />* *Smoke Exhaust System 3 %4" S.P. 4" pressure class
<br />* *Note: All ductwork that serves a dual function (i.e. return / relief and smoke exhaust (for example))
<br />shall be constructed to the highest pressure requirement. All ductwork that is part of the smoke ex-
<br />Reece, Noland & McElrath, Inc. 239000-1 Orange County Board of Elections
<br />Orange Co., NC 05/04/18
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