There is concern abouthe accuracy or uncertainty of any method of predicting the sound pressure levels of an air distribution system compared with actual sound pressure levels for the final installation. The air distribution system may consist of such components as air volume control devices, distributing ductwork, and air outlets.

To determine the accuracy of the proposed Industry Standard 885 method of predicting sound pressure levels, an air volume control device was tested to yield sound power levels under the prescribed conditions of Industry Standard 880 and then installed in a physical mock-up of an atypical application representing a hospital system requiring clean supply air.

A comparison was then made between the sound pressure levels of the actual air distribution system and the predicted sound pressure levels using the methods presented in Industry Standard 885.

Results are presented for the sound power level data of the air volume control device, the calculated sound pressure levels predicted by the Industry Standard 885 method, and the actual sound pressure levels measured in the physical mock-up.

The manufacturer’s method of determining sound power levels, the calculations for Industry Standard 885 predicted sound pressure level, and the method used in measuring the sound pressure levels in the physical mock- up are described.