Product research in controlling casing noise has developed a new method of reducing radiated noise. The technique is known as vortex shedding. When applied to terminal boxes, casing radiated noise is dramatically lowered. Casing radiation attenuation (CRA) vortex shedders can be installed in all single- or dual-duct boxes up to 7000 cfm, constant
volume or variable volume, with or without reheat coils. CRA devices provide unique features and the following benefits:
? No change in terminal box size. Box is easier to install in tight ceiling plenums to ensure minimum casing noise under all conditions.
? Factory-fabricated box and casing noise eliminator, a one-piece assembly, reduces cost of installation. Only one box is hung. Only one duct
connection is made.
? Quick-opening access door is provided in box. This ensures easy and convenient access to all operating parts without having to cut and patch field-fabricated enclosures.
? Equipment is laboratory tested and performance rated. Engineering measurements are made in accordance with industry standards. Thus, on-the-job performance is ensured. Quiet rooms result and owner satisfaction is assured.