dfowler
Mechanical
- Sep 27, 2003
- 46
I am attempting to pressurize a chamber to pre-determined pressures for varying lengths of time. I am using a fan that can output 2500cfm at 14.5”SP. The fan is connected to a VFD. I am pressure testing against a garage door to simulate wind loads so I anticipate that there will be potentially a great amount of leakage across the door. It is not known to what extent this leakage will be and most likely it will increase as the time of the test progresses. Therefore I will need to dynamically adjust for this increased leakage. This can be done by turning up the VFD connected to the fan and delivering more cfm and pressure, but this most likely has too slow of a response to compensate.
I want to employ a valve that is to be open during the test. This valve can then modulate its orifice to allow lesser flow to escape (as more does across the door) and therefore hold pressure within the chamber. I know I could build a system myself with pressure transducers, a PLC, and a valve with an actuator - but it might have too slow of a response. I am wondering if there are any “off the shelf” products that would suit my needs. I have located one integrated smart throttle valve from MKS pressure measurement and control products that seems would work for me.
I intend to dial up the VFD to a calculated target frequency that should deliver flow somewhat above the desired pressure. The excess flow (and pressure) will then bleed off through a combination of the leaks in the door and through the exit valve orifice. If the pressure is sensed less than the desired amount the valve will close more and allow less flow to escape. If the pressure is sensed greater than the desired amount the valve will open more and allow more flow to escape. This needs to be a fast response action as it would not be favorable to have high amplitude on my pressure variations.
Does anyone have any experience with fast response active control valves? These are low pressures (less than .5 psi), but relatively large flow rates for a valve with such minimal pressure. I will probably need to bleed off between 400 and 1000 cfm most of the time. I think I need a valve size of at least 6” diameter. Thanks.
Davey
I want to employ a valve that is to be open during the test. This valve can then modulate its orifice to allow lesser flow to escape (as more does across the door) and therefore hold pressure within the chamber. I know I could build a system myself with pressure transducers, a PLC, and a valve with an actuator - but it might have too slow of a response. I am wondering if there are any “off the shelf” products that would suit my needs. I have located one integrated smart throttle valve from MKS pressure measurement and control products that seems would work for me.
I intend to dial up the VFD to a calculated target frequency that should deliver flow somewhat above the desired pressure. The excess flow (and pressure) will then bleed off through a combination of the leaks in the door and through the exit valve orifice. If the pressure is sensed less than the desired amount the valve will close more and allow less flow to escape. If the pressure is sensed greater than the desired amount the valve will open more and allow more flow to escape. This needs to be a fast response action as it would not be favorable to have high amplitude on my pressure variations.
Does anyone have any experience with fast response active control valves? These are low pressures (less than .5 psi), but relatively large flow rates for a valve with such minimal pressure. I will probably need to bleed off between 400 and 1000 cfm most of the time. I think I need a valve size of at least 6” diameter. Thanks.
Davey