pressure relieving proportional valve oscillating

[djhurayt]

We are trying to replace a manually controlled pressure reliving valve in a very simple hydraulic system with a Parker AP04G2YP21CN valve.

hydraulic circuit

However every time we start to energize the valve (increase pressure to the application) the valve oscillates uncontrollably. As we try to increase the system more, the frequency of the oscillations just increases. If we reduce the input signal the oscillation rate decrease until the valve is almost wide open (virtually no application pressure) at which point the oscillations stop. If we put the manual valve back in the issue goes away. We even tried it with a different electronically controlled valve with the same oscillating results.

Any thoughts welcomed.

david

 

[itsmoked]

That valve should probably be mounted close to the pump discharge not down a pipe away from the outlet. The valve incurs a time-of-flight delay that causes a feedback delay that can lead to oscillation.

Keith Cress
kcress -

http://www.flaminsystems.com