A decompression silencer is necessary to limit the noise of the thermodynamic process of venting a gas, or more generally: a pressurized fluid.
On the one hand, it is a question of protecting personnel, i.e. limiting their exposure to noise levels liable to cause significant hearing problems, sometimes irreversible (recognition of deafness as an occupational disease is only a very small consolation for the one who undergoes it).
On the other hand, the noise impact of a decompression vent must not cause disturbances for the neighborhood; in France, the emergence i.e. the difference between the A-weighted equivalent continuous pressure levels of ambient noise (vent in operation) and residual noise (in the absence of noise generated by the vent, but measured over the operating period of the vent) must be limited - as the case may be 5 or 6 dB (A) during the day and 3 or 4 dB (A) during the night - in Zones with Regulated Emergence (ZRE) e.g. to protect, nearby: homes, building areas and areas occupied by third parties - Public Acces Buildings (PAB) and other industrial establishments: included -.
Most of the time, these two concerns simultaneously motivate the consideration of a decompression silencer, and are at the origin of the inherent definition of its acoustic performance, which, for a noise level setpoint to be respected, of course depends on the level noise upstream of the silencer (and, as always when it comes to noise: on its frequency distribution).
With regard to such an objective, the design of a decompression silencer must take into account the process data: nature, pressure, temperature, flow rate of the fluid; its construction must consider the imperatives of durability and non-corrosion (election of materials according to the nature of the conveyed fluid, and possible exposure to bad weather) as well as resistance (application of a specific construction code e.g. CODAP, ASME ).
ITS participated in the construction of a decompression silencer for a steam network for a pharmaceutical site in Belgium.
It came to a vent: the decompression silencer allowed the fluid under pressure and at very high temperature to be blow-off into the atmosphere at high temperature whereas controlling the undesirable noise emissions due to turbulence and shock phenomena.