Problem with mc quay chiller.

[HARRY 7]

Hello guys.I have a problem with a mc quay water cooled chiller model ESH.D.120 and compressor model MQC 806 s.I started the system and after a minute it stopped from oil pressure.Suction pressure 4 bar,oil pressure 4 bar,disharge pressure 8 bar.Any idea why is this happening?Does anybody have the manual of that chiller or compressor??

[frank]

Just a few guesses

Has the compressor been serviced lately? Is the oil pick up strainer clean?

Is the oil sight glass level correct?

Does the oil foam in the sight glass?

Oil safeties are there for a purpose.

[ptsac]

No oil pressure, should be about 6 to 8 bar above suction. If the compressor actually turned it could be that the oil pump is broken. There should be a linkage that sits in a slot on the end of the shaft to drive the oil pump.

[HARRY 7]

Thanks four your reply Frank.It is my first visit in this machine.I do not think that it has been serviced.The oil level is in the middle of the sight glass.No foam in the sight glass.Standing pressure of r22 is 7 bar.

[frank]

Have you measured the oil pressure on start up?

If you temporarily link out the oil control switch (2 minutes max above the knock out time) does the machine run?(to confirm that the switch is operational)

What about operating pressures during start up - are they correct?

[HARRY 7]

The oil pressure on start up is the same with suction pressure.The operating pressures until the compressor stops are LP 4 BAR,HP 8 BAR.

[frank]

The oil pressure on start up is the same with suction pressure.
I would suspect then that the oil pump needs some attention.
The oil pump should increase the oil pressure instantly on start up

[HARRY 7]

I agree with you Frank.But what about the refrigerant pressures?What do you believe about them?Thanks for your reply ptsac.

[ptsac]

The pressures will be dependent on chilled water temp and ambient. Oil pressure should still be developing regardless of level of charge.

[HARRY 7]

Temperature in water cooler 25 celcious.Temperature in cooling tower 30 celcious.

[ptsac]

There maybe a problem with charge level, however there does appear to be an oil pressure problem that will require the compressor to be opened for inspection, this is the immediate issue.

[HARRY 7]

Thanks ptsac.Do you have the service manual of this compressor??

[ptsac]

Unfortunately not, however look at Halltherms spares site
http://www.mcquayinternationalparts.co.uk/products/?cat=8130 you may get some idea from that.
There is a sump pan filter for oil pump suction, Oil is then straight to the oil pump and then fed to a filter and pressure relief device before going to bearings etc. There could be a possibility that this assembly has not been tightened properly previously and oil is escaping from the assembly. This assembly is accessible from outside the compressor I think. Gas is still going to have to be removed as is oil. prepare for some mess.

[HARRY 7]

Thank you very much ptsac.
I will check the site.But i still cannot understand the pressure difference.Don't you believe that high and low pressure are too close?
Refrigerant 22 in the circuit