Dump Tubes or multi stage expansion stage orifices can be used where high pressure media must be expanded:
During free venting or expansion of pressurised steam or gas, kinetic energy in terms of waves with high pressure amplitudes is released which leads to loud noise.
At minor amounts of venting media (500 – 1000 m³/h) and relatively low expansion pressures (1 – 2 bar), this effect causes a quite high sound pressure level – depending on application – of 115 to 125 dB(A) in 1m distance from blow off opening (e.g. piping, etc.). At bigger blow off flow and higher expansion, e.g. blowing of safety valves, the sound pressure level SPL can increase up to 150 dB(A). This generation of noise can be reduced by using Dump Tubes /expansion orifices inside the piping system. Using special designs of the multi hole cylinders, a noise reduction (sound transmission loss) of up to 30 dB(A) can be achieved.