Steam or gases, vents of high velocity, have an extremely high noise level, when critical (Sonic) flow occurs in the valve or nozzle. To provide the high attenuation, the required silencer must have a very elaborated device.
The reactive disipative silencer (SRD):
The SRDT silencer series meet some outstanding features, including jet chamber, (reactive section) diffusers, a perforated tube bundle or annular rings with high absortive filling (dissipative section) and a proper acustic packing protection. Standard nominal sizes: From DN 50 (2") outlet to DN 1000 (40"). The length of absortion section vary depending upon the attenuation required.
Some examples are:
Safety or relief valves, boilers starting up test, compressed air blowers, starting up ejectors, autoclave vents, piping blow off.
The dissipative reactive silencer ring (ARDS) differs in that the dissipative part consists of a series of concentric rings. Your attenuation is slightly less than the tube, but is cheaper and very suitable for large capacities.