In the field of soundproofing, silencers (mufflers) for purge and for valves are highly technical equipment.

In fact, it is necessary that they meet requirements of different kinds:

  • in terms of acoustics: they must (sufficiently) limit the noise linked to the sudden pressure variation, downstream of a pressurized fluid network, during venting, which (noise) is likely to create disorders for the neighborhood (even distant), and also (a fortiori) for personnel working or traveling nearby, then potentially exposed to sound levels likely to generate hearing trauma
  • in terms of fluid mechanics: they must cause an appropriate total pressure loss (depending on the case) to maintain a sufficient flow rate for the fluid transported (e.g. in relation to the duration of emptying of a tank) or to suitable operating conditions for components located upstream
  • in terms of mechanical resistance: they must withstand (in particular for their upstream stage) a pressure that is sometimes very substantial; they must have a high durability despite the physicochemical attacks linked to the transported fluid (and despite the possible expansion phenomena resulting from temperature variations if the operation is not continuous), and also despite exposure to climatic hazards (due to an outdoor installation)

This is why, to allow the expected functionality in terms of soundproofing to be maintained over time, the silencers (mufflers) for purge and for valves must be the subject of a very thorough design and of a particularly careful construction (it is not uncommon for a pressure vessel construction code to be used, and it is not uncommon for non-destructive testing of welds to be performed, even if such a silencer is not intended - during normal operatio - to contain a pressurized fluid, which it nevertheless carries).

Regarding the principles of soundproofing, silencers (mufflers) for purge and for valves generally consist of:

  • an upstream stage (single or multiple) called a "diffuser", which is a perforated sub-assembly at which the speed of the fluid can reach the speed of sound (it is therefore this which is subjected to the pressure)
  • a dissipative downstream stage, i.e. involving a lining (e.g. fibrous) absorbing sound, the geometry of which may vary according to the applications (being, depending on the case, maintained by perforated concentric shells, or by parallel perforated tubes or slots)

The sizing of the internal parts, which is the basis of the soundproofing properties of silencers (mufflers) for purge and for valves, naturally includes the consideration of the speed of the fluid in the different sections, such as to influence the phenomena of surface abrasion of the absorbing surfaces (generally covered with a fabric or metallic wool) and the self noise (i.e. the sound power related to the flow) of the silencer, which often has a major impact on the overall performance.

ITS participated in a soundproofing project near Toulon (France) by marketing a silencer (muffler) for purge and for valve, carried fluid being saturated steam.

The vast experience of ITS and its business partners in this field has enabled the development of an ad hoc noise attenuator, designed and manufactured at an affordable price, and a smooth project workflow.

Limitation of noise emissions in energy sector

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