Question -
Will a relief valve used for a hydraulic system operate at the same setting if subjected to test using gas?
I need to validate the operation of an RV used with oil but only have a test rig for testing valves using air. Will the test be valid if i use air as a test medium??
(obviously gas will expand but oil will not so I dont know how this affects the process of the test)
regards SS
S; I don't know of any place to tell you to go to find a written answer to your question. My educated guess would testing with air would wind up with the relief valve relieving at a higher pressure when used with oil. My reasoning is that the poppet on the valve would have to open only a small amount to pass air so a tighter spring setting would be necessary. When oil is applied to the air adjusted valve the poppet would have to open more to pass the higher viscosity fluid and cause more spring tension which would result in a higher setting.
I know I tried to preset a large relief valve with hand pump and found it actually relieved at a much higher pressure when applied to the 185 GPM pump it was to protect from over pressure.
One other suggestion, try your question on the Fluid Power Societies web site
I wouln't bank on getting representative results from a gas test. Gas is 'softer' with its built in spring (and higher stored energy - beware!)
Couldn't you rig a big grease gun filled with oil and plumbed with a pressure gage?
Brian Whatcott
Hmm..I may just have the thing...... I've got a high pressure grease injection gun that may just do that job......
Ta Brian... ss
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