carlosfandango
Mechanical
- Jun 29, 2017
- 3
All,
I've an application coming up where we're doing some R&D testing on air compressors, this requires a pressure map to be completed at various speeds and back pressures. Back pressure on the compressor is normally controlled via a valve downstream of the compressor outlet and subsequently controlled by a PID controller of types.
The problem is as the compressor is reasonable high flow we have a 8" pipe on the outlet but require very accurate pressure control down to 10-20 mbar level, the compressor on test will be capable of 2 bar maximum.
I'm not sure with using such a large valve on the outlet we can get this type of control accuracy on the outlet of the compressor. What has been discussed is using two valves in parallel to control the pressure ?. One larger 8" valve to manually set at a fixed point roughly around the pressure required and a much smaller valve in parallel in a PID loop to automatically trim the pressure into the desired range. Haven't managed to find an application like this online either because nobody has really tried it or it just doesn't work !!!
I've had a few recommendations on single large valve but from experience we just don't seem to be able to get the accuracy on the pressure control. Our application has a large tank on the outlet of the compressor but before the valve to damp out any pressure oscillations.
Anybody any experience or knowledge of a parallel valve application to control pressure along with knowledge of the control side of it ?, any pointers or help gratefully received.
Thanks
I've an application coming up where we're doing some R&D testing on air compressors, this requires a pressure map to be completed at various speeds and back pressures. Back pressure on the compressor is normally controlled via a valve downstream of the compressor outlet and subsequently controlled by a PID controller of types.
The problem is as the compressor is reasonable high flow we have a 8" pipe on the outlet but require very accurate pressure control down to 10-20 mbar level, the compressor on test will be capable of 2 bar maximum.
I'm not sure with using such a large valve on the outlet we can get this type of control accuracy on the outlet of the compressor. What has been discussed is using two valves in parallel to control the pressure ?. One larger 8" valve to manually set at a fixed point roughly around the pressure required and a much smaller valve in parallel in a PID loop to automatically trim the pressure into the desired range. Haven't managed to find an application like this online either because nobody has really tried it or it just doesn't work !!!
I've had a few recommendations on single large valve but from experience we just don't seem to be able to get the accuracy on the pressure control. Our application has a large tank on the outlet of the compressor but before the valve to damp out any pressure oscillations.
Anybody any experience or knowledge of a parallel valve application to control pressure along with knowledge of the control side of it ?, any pointers or help gratefully received.
Thanks