5 replies to this topic

[alirah]

Hi everyone.

How can I calculate required pipe length between venting valve and it's downstream silencer? operating fluid is steam with specified conditions before valve. silencer is expected to handle full pressure drop. 

[fallah]

alirah,

 

In general, I think it's better to be as short as possible. If there is a significant pipe length between venting valve and the silencer, the pressure drop across the venting valve might lead to high noise level couldn't completely be absorbed by silencer...

[alirah]

fallah,

 

Do you know a formula that relates pressure drop across pipe to the produced noise level within the pipe? and also, do you think there is a minimum pipe length required for the flow to reach fully developed situation before entering the silencer?

[Zauberberg]

See some of the attached papers on noise prediction. You can also download a trial version of Cadna-A noise prediction software at: http://www.datakusti...products/cadnaa

 

I don't quite understand your original post in which you say that the silencer should take the entire pressure drop. What do you mean by that? If this is the design intent, then the silencer would impose significant backpressure on the vent valve. Can you post a simple sketch of this system?

 

I'd suggest you get in touch with unit suppliers. There is plenty of them around.

 

Attached Files

•  Pipe Noise.pdf   603.62KB   32 downloads
•  Noise Prediction.PDF   47.47KB   32 downloads
•  Calculation of the Noise Emission.pdf   220.5KB   33 downloads

[alirah]

See some of the attached papers on noise prediction. You can also download a trial version of Cadna-A noise prediction software at: http://www.datakusti...products/cadnaa

 

I don't quite understand your original post in which you say that the silencer should take the entire pressure drop. What do you mean by that? If this is the design intent, then the silencer would impose significant backpressure on the vent valve. Can you post a simple sketch of this system?

 

I'd suggest you get in touch with unit suppliers. There is plenty of them around.

 

Zauberberg,

 

Thanks a lot for valuable references. I think it means that when the valve is fully open, all of the inlet gauge pressure should drop across the silencer. for example if the pressure before valve is 7.5 barg, the silencer shall be designed for 7.5 barg pressure drop and given flow rate. see the sketch attached.

Attached Files

•  silencer-PID.pdf   84.51KB   35 downloads

[Zauberberg]

I agree with the design conditions. If the silencer gets blocked/plugged anytime in future, it will see full pressure of the upstream vessel.

 

I don't think the silencer will take full pressure drop though - there is a globe valve and piping upstream. The amount of actual pressure drop consumed by the silencer will depend on the silencer design. Manufacturer will tell you the details.