View Full Version : Oil Lifting Problem -Bitzer Screw Compressor

14-12-2014, 04:55 AM
Hi forum ..

Recently we Installed new Screw Compressor , Bitzer Semi Hermetic - HSN7471 Compressor.

In the Oil was lifting continuously and not coming back to compressor.
Initially there was suction accumulator , we removed it ,after 4 days oil separator is almost empty. at that suction pressure is 10psi, discharge pressure is 190 psi ,oil pressure is 175 psi.
chiller inlet minus 14deg outlet minus 18.4 deg.
Chiller is operating with electronic expansion valve

Please any one suggest what may be the issue, why oil is not coming back .


Glenn Moore
14-12-2014, 03:55 PM
Can you tell us what refrigerant your using, the type of oil in the compressor , and also the model of oil seperator fitted

15-12-2014, 12:06 AM
What was the logic behind removing suction accumulator?
as per previous post, refrigerant used etc.. Bitzer screws require factory recommended oil and it will be hot entering compressor, loading sequences are important as well during pull down, if gas velocities are too high the oil will carry over into system.

15-12-2014, 02:59 AM
after you checked all thing as Magoo said ,
you check the liquid coming back from you system and check your electronic expansion valve
also when it happen ? is it in start time or changing the capacity of system?