prEN ISO 7235 rev

Acoustics — Laboratory measurement procedures for ducted silencers and air-terminal units — Insertion loss, flow noise and total pressure loss prEN ISO 7235 rev

Scope

<p>This document specifies methods for determining</p>
<ul>
<li>the insertion loss, in frequency bands, of ducted silencers with and without airflow,</li>
<li>the sound power level, in frequency bands, of the flow noise (or regenerated sound) generated by ducted silencers,</li>
<li>the total pressure loss of silencers with airflow, and</li>
<li>the transmission loss, in frequency bands, of air-terminal units.</li>
</ul>
<p>The measurement procedures are intended for laboratory measurements at ambient temperature. Measurements on silencers <em>in situ</em> are specified in ISO 11820.</p>
<p>It is to be noted that the results determined in a laboratory according to this document will not necessarily be the same as those obtained <em>in situ</em> (installation), as different sound and flow fields will yield different results. For example, the pressure loss will be lower under laboratory conditions than <em>in situ</em>, but will be comparable between different laboratories.</p>
<p>This document is applicable to all types of silencer including silencers for ventilating and air-conditioning systems, air intake and exhaust of flue gases, and similar applications. Other passive air-handling devices, such as bends, air-terminal units or T-connectors, can also be tested using this International Standard.</p>
<p>It is not applicable to reactive silencers used for motor vehicles.</p>