I have been experiencing major oil loss in our low stage 250vld Mycom screw compressor.
The problem became expensive 2 years ago.
At first the losses were minimal having to add oil once a week.
2 years ago I changed out the coalescers with frick coalescers not realizing the error I had made. Oil loss was crazy. I changed back to the proper Mycom coalescers and the problem continued.
I have spoken with Mycom about the problem periodically and really have made no progress.
The suction check valve was changed and oil loss to the low side was eliminated. Half the battle was won as we were still losing out of the discharge to the intermediate side.
I noticed that at some point the liquid drainer on the coalescer section of the seperator (oil return to suction of compressor) was removed. I tried installing one with results. The coalescer glass was showing an oil level (I know not a good thing) but I was loosing less oil (Approx 5 gal per day)
Ideas are running out.
If the load is removed from the compressor as soon as it starts unloading it will cutout on low oil pressure. When this happens before the compressor can be started the slide valve must be unloaded. During this process we need to add 5 to 10 gallons of oil to keep the pump pressure up and unload the slide valve.
By the way it is a full time oil pump and oil temperature is where it should be.
Mycom keeps thinking that the oil seperator is undersized which it is but I beleive another problem is there as why would the problem get worse.

We have also tried an anti-foaming agent with no success.

Could this be a clearance issue?
Could this be a bad seal on the slide valve piston?
Does anyone have any other suggestion?

Thanks for reading sorry to carry on but I wanted to give as much info as possible.