This International Standard specifies the substitution method for determining the insertion loss of ducted silencers. It sets out requirements for determining
— the insertion loss, in frequency bands, of silencers with and without air flow;
— the sound power level, in frequency bands, of the flow noise generated by silencers;
— the total pressure loss of silencers with air flow.
The measurement procedures are intended for laboratory measurements on silencers but may also be used for in situ measurements on silencers if the requirements of this International Standard can be met.
This International Standard applies to silencers for ventilating and air-conditioning systems which are usually connected to duets or splitter absorbers mounted in duets. Other duet elements, such as bends or T-connectors, may also be tested using this International Standard.
This International Standard does not apply to reac-tive silencers used for motor vehicles.
NOTE 1 Exact information on the precision of the method cannot be given at this time. Interlaboratory tests are necessary for the determination of the reproducibility standard deviation ?R of the method (relevant terms and methods are given in ISO 5725). The following estimates of the reproducibility standard deviation, ?R, were deter-mined from tests made on splitter-type silencers.
DS/ISO 7235:1992 history
1992DS/ISO 7235:1992 Acoustics. Measurement procedures for ducted silencers. Insertion loss, flow noise and total pressure loss