R11 Centrifugal Chiller Oil Problem

We have 3 centrifugal chillers (water cooled) at a site in town. There is a problem with oil return/oil pressure and this has been happening off an on for a while. The service technician changed the filters etc last week, and left the valves on the oil line closed. We opened them up but the machine is still tripping out on low oil pressure. The sump is half full and empties when the oil pump runs. We backed off the chiller to try and get some oil back and I believe he added some to top up as well. I went over earlier and closed off the purge drum and tried to get the chiller running to get some oil back, but nothing would work. Our service people are going back to drain the oil from the evaporator and check the filters. Personally I think the compressor maybe the problem. condenser pressure was a little low, and oil at about 50kPa

Hi,
Check your compressor, low head pressure high suction... you will get low oil pressure.

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Originally Posted by guapo

Hi,
Check your compressor, low head pressure high suction... you will get low oil pressure.

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I thought it was the compressor as the suction pressure seemed high. Although in a vacuum, it was still high. The condenser pressure was on the low side, compared to the other two machines. It had been running at -45kPa suction. The other two machines oil pressure was at 150-200kPa. I think this machine had oil pressure of around 50-80kPa at most, and condenser pressure of 20kPa ?? (I'm struggling to get away from psi). Anyway, my thought was towards a worn bearing, as although the oil temp was OK initially, it could not maintain sufficent oil pressure, even after one of the service techs added oil to get the pressure up. It just seems that the compressor is not compressing properly. Although they are going to check the oil filters and drain out the oil and refill, I think the problem is deeper.

Excuse me! R11? (Not banned there yet?)

What brand?

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Originally Posted by Sanderh

Excuse me! R11? (Not banned there yet?)

What brand?

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You can run the chiller but if you recover the refrigerant it must be destroyed. York dating back to the very early 80s

Lucky B*st*rds! In Europe one's not even alowed to use it and you're the one's with the "hole" in the ozone layer!

We sometimes have problems with centri's running in low load is oil loss to the condensor which ends up in the evaporator. The older ones had just a return line to the compressor and the only way to get it back was adding some oil and let it run at full load for a few hours and then remeoving the excess oil. Leaving the extra oil in will result in the same problem.

What kind of oil pump is on it? could also be that it's not pumping enough or way too much an thus loosing the oil from the sump!

What Type And Model Is The Machine.

York Turbopak/codepak

These Have An Auxilary Oil Pump As Well As A Pump On The Drive Train.
Aux Pump Starts And Developes Oil Pressure.the Compressor Starts And The High Speed Drive Train Pump Takes Over.there Are A Series Of Venturis In The Oil Lines.
I Have Had A Problem Where The Machine Keeps Using Oil And We Found That The Large Circlip That Holds The High Speed Laybrinth Had Popped Off And The Oil Was Being Diluted Into The Refrigerant.

Cheers

What are the run hours on this chiller? Could be time for a rebuild. Any unusual noise at start up? Oil analysis results? If rebuilt a conversion to R123 is another option you could take. :)

another old thread,
yorks are notorious low load oil pumpers, high suction low discharge could just mean the machine is nt loaded , load the machine up if oil level is low check the oil return solenoid, is it energised, if not check magnetic switch on upper float,keep condenser pressure up this will help the oil return process.
obviously this will be of no help if there is a mechanical problem (worn bearings , thrusts , seals etc)