Atmospheric Vent Silencers - Frequently Asked Questions

Here are a some of the common things that we get asked about atmospheric silencers

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If you can't find the answer to your question in the list below send us an email and we will do our best to answer you directly

What noise level do I need to go for ?

There is no standard noise level for silencers, however international standards commonly agree that 85dB(A) at 1 metre is a safe level to protect workers from harmful levels.

What is "pressure drop" ?

Pressure drop is the difference between the pressure going into the equipment and that coming out of the equipment.

Why can't my pressure drop be zero ?

No, it is not possible to have zero pressure drop. You always need a change in pressure to get the flow to move from one part of the system to another. If the pressure was the same on the inlet as it was on the outlet, then there would be no flow.

What is the maximum pressure drop I can have ?

You can have as much pressure drop as you want, however you need to check that the capacity of the system to achieve the required flow is not adversely impacted by a high pressure drop across the silencer. Typically this might mean that pressure drop would be limited to 50% of the pressure at the inlet to the discharging valve. However, in cases where the details of the discharging valve are not known then it is normally safe to adopt a maximum pressure drop at 10% of the upstream pressure.

What is the minimum pressure drop I can have ?

Wind loads can be checked for all equipment, however it can be generalised that equipment that is small (less than 500mm in diameter) and short (less than 2,000 metres tall) will not be impacted by wind.

Is the inlet diffuser pressure rated ?

All our inlet diffusers are designed and tested as though they were part of the piping, so this will mean formal design calculations are done, material certification is provided, welding will be by certified welders, NDT, such as x-ray, and a pressure test will be carried out. If the diffuser is to be used in the European Union we will also CE mark the unit.

What is liquid carry over ?

Liquid carry over is where droplets of liquid are entrained in the gas stream and enter the silencer. In a separator silencer these droplets are removed from the gas stream in the knock out pot part of the silencer before the gas exhausts to atmosphere, whilst in a standard silencer they would be blown out of the discharge.


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