Noise & Vibration Considerations

As a consequence of the expansion and compression processes which are occurring within the Ejector, aerodynamic noise levels in excess of 100 dBA at 1.0m from the Ejector can sometimess be created during normal operation. Noise will be emitted from the unit from three sources; Discharge line, Suction line or the Ejector body itself.


Noise can sometimes be emitted from the discharge line of the Ejector into the downstream piping system. If not attenuated, this could cause noise propagating in the downstream piping and equipment. To prevent this (and to ensure the noise emitted from the downstream piping system is within the required limit), an in-line Silencer can be installed in the Ejector discharge piping. This will prevent the onward transmission of noise into the downstream pipework and equipment.

Ideally, this Silencer would be located immediately onto the discharge connection of the Ejector, as any exposed pipework between the Ejector discharge point and the Silencer could emit excessive noise. In these cases, noise can be reduced to acceptable levels by acoustically insulating such pipework sections.

Ejector complete with acoustic lagging for noise reduction
Sometimes noise can also be emitted from the suction line of the Ejector. Again, if not attenuated, this could cause noise propagating in the upstream piping and equipment. As above, the installation of a Silencer in the LP line upstream of the Ejector, together with the application of acoustic insulation of the line between the LP inlet point of the Ejector and the Silencer will reduce noise to acceptable levels.

Acoustic Insulation

Noise is often emitted from the body of the Ejector into the surrounding environment. This noise can be easily reduced to the required limits within the application by an appropriate acoustic insulation system. The typical acceptable noise level is 85dBa at 1m from the Ejector. Both Silencers and acoustic systems can be supplied to maintain even lower noise levels if required.

Ejector complete with acoustic lagging for noise reduction

For applications at un-manned facilities, it may be possible to omit some (or all) of the acoustic insulation, depending on noise levels and allowable limits. The Ejector and Silencers can be installed in any orientation to suit site conditions.

Anti-Vibration Mounts

Although very rare, the supports of the Ejector and Silencers can be fitted with custom designed Anti-Vibration Mounts. It must be stressed that this is only in exceptional circumstances and as such rarely required.

The use of Anti Vibration Mounts will reduce the transmission of vibration and noise from equipment to the support structure of the plant and simultaneously reduces the vibration induced noise from the structure. The resilient material (usually rubber) of the Anti Vibration Mount must be appropriate for the compressive stress to which it will be subjected. In turn, the compressive stress will be made up of the bolting load which attaches the AVM to the support structure, together with the compression load exerted by the equipment when in service.

Using an Ejector to replace a compressor stage.

When designing Anti-Vibration Mounts, it is important to know all the external loads that will be transmitted onto the Ejector or Silencers (from pipe loads for example) so that the compressive stress applied can be accurately calculated.