View Full Version : Hallscrew compressor

09-11-2007, 06:09 AM

We had a problem with a HS2028 on a water chiller PHE system. It has been in for a number of years. We have just started service work for the client so not sure of history. Anyway the compressor would start and have high discharge temp problems straight away. We have had the side cover off and found the internal oil drain mechanisim is not there, just a hole. Has it been taken out or has it somehow come out during operation? Anyone struck this before?

09-12-2007, 05:16 AM
Yes ,years ago it was an external danfoss check valve NRMA danfoss. later models had a ball bearing installed internally between suction chamber and discharge line. The only way to replace it is to remove comp of base.I think circlip comes adrift and ball drops out.This ball or NRVA check valve (without spring) is for draining oil out of main rotor / suction chamber before start up,when pressures are equal.Because unit usually has prelube pump for bearings and to unload it if required.

15-12-2007, 05:56 PM
hi guys,

hall screw needs control over discharge temeprature.
that's why hall has liquid injectin port for such event.

it is between 80 to 90degC of discharge temp you have to maintain otherwise many other problems come.

we have installed few from scratch. not a single problem we face to date.

16-12-2007, 06:32 AM
Hi Defriguy,
What is your oil cooling system? external or liquid injection? Do you have good compression?