Vent Silencers

In process industries countless safety valves and control valves are to be found as in petro-chemical, chemical plants and in electricity power generating stations. Opening of these valves to vent steam, gas or vapour is accompanied by high levels of noise; 150 to 160 dB(A) is not uncommon. Potentially a great risk of operator hearing damage in addition to the burden upon the environment especially through venting during the night hours. Stringent limitations on noise production are imposed. Fitting vent silencers can reduce accidents arising from shock reactions, eliminate noise-induced hearing damage in personnel and prevent complaints from neighbours.

Principle of Operation

Basically each Q.E. vent silencer comprises a diffuser, an expansion chamber and an absorption section. In the diffuser and expansion chamber the pressure of the venting vapour is reduced in stages to atmospheric pressure , even from 100 bar. At the same time the vapour velocity is reduced. A shift in the noise spectrum towards higher frequencies is achieved so that absorption at these frequencies is more easily made. The venting vapour is lead through vapour channels in the absorption section where sound energy is converted to friction heat.

Available As

Standard Silencers
Q.E. standard silencers economically priced in carbon steel (internally and externally) with absorption material in mineral wool. The exterior is particle-blasted to SA 2.5 and coated with 40 micron DFT of zinc rich prime paint.

Custom Design
Q.E. has also specialised in designs of silencers to comply with customer specifications. Our extended experience is at your disposal in solving complex noise problems and in the translation of extreme demands into practical solutions and our continuing drive to be leaders in our chosen fields is evidenced by the successes that we have demonstrated.

Calculation

All components exposed to internal pressure are calculated and constructed to comply with the ruling Pressure Vessel Code for the district or industry in which the silencer is to operate. Examples of such codes are ASME VIII divisions 1 and 2, EN 13445 (European code) or National PV Codes like AD2000, CODAP, BS5500, Dutch Rules of Pressure vessels, GB150 etc. The final design will be based upon:

• - The fluid being vented
• - Its quantity (in mass flow units ‚ kg/h)
• - The fluid temperature
• - The fluid pressure upstream and downstream from the    valve
• - The required (or permitted) noise level
• - The nozzle connection size