Selection of Large Rectangular Silencers

A silencer of width "W" and height "H", which is larger than the maximum standard silencer dimensions of 48 in. x 48 in. (1219 mm x 1219 mm), can be fabricated as separate standard silencers (2 separate silencers banked to fit 1 larger duct shown below). For either option, the performance specification can be selected for the chosen unit size using the rectangular silencer selection procedure. For easier sizing use Kinetics web-based selection program.

Baffles can be installed vertically or horizontally, with height limitations of 168 in. (4267 mm) and 96 in. (2438 mm), respectively. For large banks do not use horizontal baffles.

Application Guidelines

Published silencer pressure drop data assumes ideal flow conditions. Higher pressure drops may result from system effects.

For a more detailed description of the design of air-handling systems and related information, refer to ASHRAE publication "Application of Manufacturers' Sound Data", 1998, as well as the ASHRAE Handbook.


Absorptive rectangular silencers as shown on the contract drawings, or as tabulated shall be installed to reduce sound transmission to occupied spaces.

Silencers shall be of the sizes and lengths shown, and shall consist of (16 ga (1.61 mm)) (18 ga (1.31 mm)) (20 ga (1.01 mm)) (22 ga (0.85 mm)) steel outer casing and (18 ga (1.31 mm)) (22 ga (0.85 mm)) (24 ga (0.70 mm)) (26 ga (0.55 mm)) perforated steel interior partitions, all of which have a galvanized steel, G90. Standard silencers shall maintain structural integrity to a differential operating pressure of (5 in.w.g. (1244 Pa)) (8 in.w.g (1990 Pa)) (10 in.w.g. (2488 Pa)).

Acoustical fill material shall be continuous strand fiberglass of a density calculated to provide the published acoustical performance.

Silencers shall exhibit a dynamic insertion loss not less than that shown in the specifications. Pressure drop under design airflow shall not exceed that shown, as determined by the manufacturer. Selected silencers have been tested to ASTM Standard E477-06a and AMCA 1011-03 at an independent testing facility.

Mechanical Systems

Vibration Isolation Seismic & Wind Noise Control