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Blow Off Silencers

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Silencing equipment

We will help you with your requirements for silencing equipment. Most common application that we handle is for blow off or start-up of steam or other gases, but we can also provide silencers for ventilation ducts , chimneys, gas turbines, fans, compressors, steam turbines and many other types of applications.


Blow off and start-up silencers

When releasing high pressure gases to atmosphere, a large amount of cinetic energy is freed due to the pressure difference. The pressure difference causes a dramatic increase in velocity which results in high sound emissions which need to be reduced.

The emissions can very simply be decreased by means of our well proven solutions with multi-stage silencers. First stage is the inlet pipe itself, second stage is the expansion unit and if required (most common) a final step with absorption silencing is applied.  Our expert knowledge base and knowhow is in the expansion unit, where the gas volume is allowed to expand in stages inside down to atmospheric pressure. Depending on its design a sound reduction of up to 70 dB(A) can be achieved at best.

All of our silencers are custom built to the specific application requirements.

Want to know more about silencers?

Peter Sundbaum

+46 -36 36 126 peter@campreq.se

To design the best silencer fit for your application we will need the following information

  • Sound level requirement, incl confirmed distance and direction (angle) to the measuring point
  • Gas flow (kg/h, incl. possible variations min/design/max)
  • Gas composition
  • Temperature and pressure before valve
  • Temperature and pressure before silencer (if unsure, we will ask you some simple follow up questions to help calculate this)
  • Possible deviating / off-set operation points (such as special pipe design requirements, if any)
  • Dimension of the incoming piping
  • Type of required connection (welded in place or flange connection)
  • Possible material preferences



Silencers for gas turbines, fans, compressors and steam generators

The acoustic requirements for gas turbine plants are increasing. Therefore, sound-absorbing equipment is required. The noise level from turbines is very high, especially at low frequencies. Silencers for gas turbines are specially designed to withstand high temperatures in combination with high gas velocity and turbulent flow. The mufflers can be placed directly after the gas turbine in the exhaust duct and / or after the exhaust boiler.


For dimensioning of silencers, the following must be taken into account:

  • Gasflow & temperature
  • Dynamic damping
  • Flow rate and pressure drop across silencer
  • Transmission losses through exhaust boiler, chimney, ducts and bends
  • Secondary sound sources (burners, etc.)
  • Mechanical strength of materials to withstand vibrations and turbulent flow

Sound insulation and sound hoods

Laws and regulations require sound-absorbing equipment in industrial plants and surroundings. Sound insulation and sound hoods are installed to absorb sound emitted from machines and other equipment to minimize the sound effect in the environment. The sound-insulating properties of sound insulation and sound hoods are largely dependent on the density of the sound-absorbing material.

Diesel and gas-powered internal combustion engines, chillers and compressors generate low-frequency noise, partly with significant frequencies and max. levels up to about 200 Hz. In gas and steam turbines, high-frequency sound dominates with a sound maximum at 1000 to 4000 Hz

Inline silencers

In many industries there are long channels and wires that form a source of sound. The sound is created by control dampers, compressors and fans and the like that are installed in the lines. To reduce sound from channels, an inline muffler must be installed. This muffler muffles both gas-borne sound and body sound from ducts.

Reactive silencers

In lines with pulsating sound, very high noise levels occur with clear sound peaks. An effective reduction of the sound level can be achieved with a reactive muffler.

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