Quote Originally Posted by l2embo View Post
1. Evaporator is a flooded flake ice drum ( with surge drum ) with an oil trap at the bottom of it and an oil drain valve. we regularly open and drain the oil which carried from the system. The oil is very dirty and not usable.
2.Evaporator superheat is 5 degree centigrade
3. The oil is suniso 4GS and refrigerant is R22
4. Oil separator pipe size and discharge line size are the same. Usually for screw compressors we use bigger oil separator than you can see in the picture but since the catalog doesn't mention any possibilities for using an external oil separator we use this.
5. Yes, the oil almost always foam in sight glass.
6. Discharge temperature is about 90 degree centigrade and discharge pressure is 150-165 psi.
7. We are mostly sure that the oil return from oil separator. but there is a doubt that oil could possibly migrate into 3 meter vertical suction line and to the surge drum because of the pressure difference. ( discharge pressure 150/suction pressure 25 psi) there is no connection embedded for the oil return so we used suction connection for that. there are also doubt for using oil cooler route for oil return which we again worries of oil wrong direction passage from oil cooler to oil separator due to little pressure difference.

The other point is that when we reduce the capacity from 100 to 75 and so on the oil foam will return in sight glass more.

this is the link for the instruction manual for this compressor for your reference. https://www.hosbv.com/data/specifica...HandBook_E.pdf
your advises would be precious for me.
Originally you say you were draining oil from ice machine & was very dirty?
Now you get nothing.
You can return oil from evaporator automatically if set up correctly, but if in condenser, which I find hard to believe, then eventually it will pass into evaporator.
Pump out condenser, see if any oil in it like people suggest.
Better still, put R32 & air in it, then pump it down, but wear fire suit