Silencers for safety valves

Every industry makes use of safety valves to protect systems against overpressure. When these safety valves are opened to vent steam, gas or vapour it is often accompanied by excessive noise levels. Values as high as 150 to 160 dB(A) are not unheard of. Such high noise levels could compromise the hearing of your employees and complaints may also be received from surrounding residential areas or factories.

ERIKS has a complete range of vent silencers / silencers available and we can help you choose the type that is most suitable for your needs.

Operating principle

While venting a safety valve, kinetic energy from the medium is converted into pressure waves with a high amplitude.

This effect causes, even at a low capacity or a low reduction of capacity of 1 to 2 bar, a sound pressure level of between 115 and 125 dB(A) at a distance of 1 metre from the opening, depending on the application. With large volumes, combined with high pressure drops (e.g. with safety valves) the sound pressure level at a distance of 1 metre could even elevate as high as the aforementioned 150/160 dB (A).

A silencer consists of a diffuser, an expansion chamber and an absorption chamber. In the diffuser and the expansion chamber pressure is reduced in several steps, independent of the initial pressure, to atmospheric pressure. 


Speed is simultaneously removed from the medium and the medium passes through channels in the absorption area where the sound is reduced even further.

Information required

The following process values are required to make the appropriate selection:

  • Medium
  • Capacity
  • Medium temperature
  • Pressure before the valve and after the valve
  • Sound level required
  • Connection size


When it comes to safety valve noise absorption the maximum allowable counter-pressure caused by the silencer and piping after the safety valve depends on the construction of the safety valve. Without bellows the maximum counter-pressure can be increased up to 15% of the preset pressure. If this value is exceeded the safety valves may not vent at the correct preset pressure and as a result the calculated pressure cannot be obtained. These values are different for safety valves with bellows or Pilot Operated Safety Valves.

If you require more information, please contact our safety valve, bursting disc and silencer specialists.


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