Double Wall Ductwork Specification

Construction class that is upstream of the vav boxes shall also meet seal class c.

Double wall ductwork specification.

A comprehensive duct layout indicating sizes design airflows pressure class and routing of the duct system. The perforated inner shell has 3 32 diameter holes staggered at 3 16 on center for a clear open area of 23. Double wall insulated spiral is available with solid or perforated liners. In addition to the above any variable air volume system duct of 1 w g.

Duct wall penetrations 4 w g. Standard acoustical double wall is for noise control. Langdon provides stainless steel and aluminum double wall duct and fittings for a wide range of environments including hospitals laboratories food and pharmaceutical plants. And up b all transverse joint and longitudinal seams 3 w g.

When a perforated inner liner is specified a retaining fabric must be wrapped between the perforated inner and the glass fiber insulation. Constructed of a perforated inner shell surrounded by a layer of insulation and covered by a solid outer shell. Double wall fittings are manufactured on our state of the art fabrication equipment. The outer shell of double wall construction for 2 or 3 inch insulation thicknesses finish 2 times the insulation thickness larger 4 inch and 6 inch respectively.

Mylar barrier is available as a barrier between perforated liner and insulation. All double wall fittings are fabricated with stiffening beads on duct sizes 19 wide and larger which have more than 10 square feet of unbraced panel. The types of fittings to be used based on the designer s calculations of fitting losses i e square versus 45 entry taps conical versus straight taps etc. Double wall duct and fittings will consist of a perforated or solid inner liner 1 thick x 1 0 lb ft layer of glass fiber insulation and a solid outer pressure shell.

C transverse joints 2 w g. All double wall ductwork and fittings shall be constructed with an outer galvanized wall and a perforated inner galvanized liner. Information required for duct construction 1. Standard connections are slip fit with couplings.

Ductwork will be spiral seam construction made from g 90 or better galvanized steel conforming to astm a653 a653m and a924 a924m standards lock forming quality lfq. This requirement is applicable to 20 gauge or less in thickness and 3 w g. Langdon fabricates double wall ductwork with an inner perforated metal liner and fittings with an inner solid metal liner. Gasketed up to 36 flanged or spiralmate by ductmate industries connections are also available.