Grasso Compressor Oil carryover

Gents,
Dealing with an issue and need your suggestion please...
1)We have Grasso P type screw compressors (Model: PR-P36S-28) working on NH3 for cold store plant. Our LS compressor is under breakdowna and replacment underway. Currently running Swing and HS compressors.
2) Our Swing compressor oil separator is constantly showing low oil level from sight glass(extremly bottom) even after charging oil. SP= 2.3 bars, DP =11.7 bars, OP =14 bars, DP for fine fiters =3.2 bars as everything is normal. We already replaced the fine filter catridges and oil filter as well with proper torque(this problem is not after changing and is before).
3) We have cleaned the return line and its filter, flushed the service valve line to separator.
4) When we are depressurising, oil level is returning back to separator from compressor.
Need your guys opinion please....

Thanks & BR.

Hi Amjad123,

Check your suction valve NRV (non return valve). Maybe you losing oil on the spin back when the machine cycles off / shuts down. Also check the oil return from coalesce section is correctly set.

Amjad123,

DP for fine filters is 3,2 bar, so this is pressure across coalescer filters in oil separator?
If so, not correct, what is high side compressor pressure drop.

Horizontal, or vertical oil separator?
Type of oil cooler

Oil return would expect to feel warm, maybe sight glass can indicate as well

If you add oil, it disappears, are you then draining it from somewhere, does another machine oil level increase?