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.