Specifications - City of Montpelier, Vermont

Title:Montpelier District HeatingCity of Montpelier, VT15891 – Metal Ductwork & AccessoriesIssue Date:September 28, 2012Page #:4 of 19A. Static Pressure Classifications: Except where otherwise indicated, construct ductsystems to the following pressure classifications:1. Supply Ducts: 3" water gauge, positive pressure.2. Return Ducts: 3" water gauge, negative pressure.3. Exhaust Ducts: 3" water gauge, negative pressure.B. Seal Class: Seal all new and existing sheet metal ducts to SMACNA Seal Class‘A’.PART 2PRODUCTS2.1 DUCTWORK MATERIALSA. Exposed Ductwork Materials: Where ductwork is indicated to be exposed to viewin occupied spaces, provide materials that are free from visual imperfectionsincluding pitting, seam marks, roller marks, stains and discolorations, and otherimperfections, including those that would impair painting.B. Sheet Metal: Except as otherwise indicated, or specified fabricate ductwork fromgalvanized sheet steel complying with ASTM A 924 and A 653, lockformingquality, with G 90 zinc coating in accordance with ASTM A 90.2.2 MISCELLANEOUS DUCTWORK MATERIALSA. General: Provide miscellaneous materials and products of types and sizesindicated and, where not otherwise indicated, provide type and size required tocomply with ductwork system requirements including proper connection ofductwork and equipment.B. Fittings: Provide long radius type fittings, radius is 1½ times to centerline of ductwidth. Unless specifically detailed otherwise, use 45° laterals and 45° elbows forbranch takeoff connections.C. Duct Sealant General: Nonhardening, nonmigrating water based mastic orliquid elastic sealant, type applicable for fabrication/installation detail, ascompounded and recommended by manufacturer specifically for sealing jointsand seams in ductwork.1. Hardcast: Flex Grip2. United McGill: United Duct SealerMETAL DUCTWORK AND ACCESSORIES 15891 4