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Proportional Valve

Proportional Valve

Proportional Valve

I have a 0 to plus or minus 10 volt proportional valve that is controlling a cylinder. It is a parker D31fh type. The hydraulic pressure ranges from 1600 to 1850. The pump will start at 1600 and shut off at 1850. My problem is with the new proportional valve it cycles the pump every 4 minutes versus the 20 minutes it cycled with the old D3W directional control valve. We have replaced all the lines and filter to clean the oil and even rebuilt the cylinder the valve was feeding. We feel like the oil is clean. With the higher cycle times we are goig to have more equipment failures. Any suggetions?

RE: Proportional Valve

The proportional valve doesn't do the control some controller does that. Could some change have happened to the 'controller'? How does the controller work? Usually the controller monitor something to do some math and come to a command output to run the proportional valve. That sensing could also be at fault.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Proportional Valve

Thanks. It is controlled by a plc output. It seems to be controlling well. With the internal leakage of the proportional valve it is causing more cycling of the pump and motor. I am not sure what is causing the internal leakage. Can the proportional valve be calibrated to zero? the manual says it can. Would a sandwich valve help with the leakage?

RE: Proportional Valve


Can the proportional valve be calibrated to zero? the manual says it can. Would a sandwich valve help with the leakage?
No, the leakage is a function of tolerances and how the spool is cut. The D31FH has a little bit of overlap so the spool shouldn't be leaking much when at rest. There will always be some leakage.

Peter Nachtwey
Delta Computer Systems

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