JE Hall HSO 4222 screw not pumping down.

Gents,

First time posting so bear with me,

I have a JE hall HSO4222 that has been tripping on oil pressure, it appears as though the compressor is not pumping, I have carried out a pump down test and it will sit there running with the suction dropping slightly but not pumping down.

I tested this on another unit on the site and it pumped down straight away, the compressor that was proved to pump down was installed in position of the original (that wouldn't pump down), after the unit was vacced and charged it ran up nicely pulled the temps down all pressures looking good, watched it for an hour or so and went on our way happy it was repaired.

Following day got a call to say the plant had gone down again, to find it was doing exactly the same again with the replacement compressor in place.

Proper confused...

Anyone else had this issue, or can somebody throw some ideas my way as I'm stumped?

Thanks in advance

:o

Hi Did you inspect the star wheel on the removed screw?
Would recommend inspecting removed unit and you may have a similar failure on replaced unit ie liquid slugging back etc

Have you checked external loading controls (probably operated by oil pressure). Maybe its running unloaded and thats why its not pumping down?

A compressor can't and won't "pump" that's what pumps are for, the secret is in the name ;)