Comparison of the New Test Procedure Proposed by Hevac for Acoustic Louvres With in-Duct Silencer Static Insertion Loss Measurements

The British Standard for testing in-duct ilencers.354713, specifically excludes acoustic louvres and states that they should he considered as a partition which should be tested between two reverberant rooms using 552750.It is considered more appropriate by some manufacturers to test louvres as though they were in-duct silencers.pending publication of any new standards.The Heating, Ventilating and Air Conditioning Manulacturers Association, HEVAC, Acoustic Group 1990.have proposed a method of testing which attempts to simulate industrial installations by comparing the noise emission from an aperture in the external wall of a reverherant chamber with and without the acoustic louvre installed.This method also produces additional iniormation on directivity.This paper compares these test methods and also the results obtained from sound pressure and intensity measurements.