running the oil pump to check oil level

I've got two 750 ton York OTS4G chiller units (old school, vintage '75). Our operators have been checking the oil level in the standby unit (the one not in operation) by running the oil pump for 5 minutes and then recording the oil level. They do this once per day, every day on their rounds. Keep in mind that we swap chillers every two weeks, so the one in standby has this done once a day every day for 14 days before it is placed in service. One tech rep told me that wasn't a good indicator of oil level because running the oil pump without the chiller in operation moves the oil around in the chiller without the oil return system functioning to bring it back to the reservoir, and that some oil could migrate to the condenser. I'm looking for some additional technical justification to remove this activity from their rounds. Any thoughts?

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Originally Posted by Ice Queen

I've got two 750 ton York OTS4G chiller units (old school, vintage '75). Our operators have been checking the oil level in the standby unit (the one not in operation) by running the oil pump for 5 minutes and then recording the oil level. They do this once per day, every day on their rounds. Keep in mind that we swap chillers every two weeks, so the one in standby has this done once a day every day for 14 days before it is placed in service. One tech rep told me that wasn't a good indicator of oil level because running the oil pump without the chiller in operation moves the oil around in the chiller without the oil return system functioning to bring it back to the reservoir, and that some oil could migrate to the condenser. I'm looking for some additional technical justification to remove this activity from their rounds. Any thoughts?

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Great choice of name Heather.

Well I have quite a good reference Library of York data.
But I doubt I will have anything that goes back to 1975.
As they say I will have to "phone a friend" but I doubt there are any electronic manuals.
I have to say running the pump to read the oil level does sound strange.
Have you asked the operators if anyone can remember why they do this??
I suppose you could argue that the oil whilst it is being pumped around the Comp was the closest to a Running condition without actually running it!
But why! Surely 2 sets of readings are OK.
Good luck with this one!
Cheers Grizzly

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Originally Posted by Grizzly

Great choice of name Heather.

Well I have quite a good reference Library of York data.
But I doubt I will have anything that goes back to 1975.
As they say I will have to "phone a friend" but I doubt there are any electronic manuals.
I have to say running the pump to read the oil level does sound strange.
Have you asked the operators if anyone can remember why they do this??
I suppose you could argue that the oil whilst it is being pumped around the Comp was the closest to a Running condition without actually running it!
But why! Surely 2 sets of readings are OK.
Good luck with this one!
Cheers Grizzly

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When I ask, "Why? When did you start doing it this way?" they all seem to remember nothing...but I get, "We've always done it this way," or "10 or more years ago, when this other guy was the engineer, he had us start doing this..." The York Tech Rep says not a good idea, but I'm going to need more technical information than that to have a firm basis for taking it out of their rounds guidance. And this may not be particular to the vintage chillers I have...I mean, even the new ones come with oil pumps, right? I wonder what the guidance is on the new ones for checking oil level? Any thoughts?

Ice Queen.
We have some exceedingly good and experienced Engineers Form your side of the pond.
So hopefully they can respond.
Personally I have a fair amount of York experience amoungst others.
And I cannot think of Any Manufacturer that requires what you describe.
My reason for caution was that I know from experience that Some York equipment is different in U.S.A. to ours (U.K.)
The only time that I can think of when a pump is ran without the comp is "pre-lube" prior to start up.
Anyway hopefully some of the other guys can help.

Interesting post thanks Grizzly

Heather

On the more modern york centrifs the prestart sequence was to run the oil pump then look at the flow switch to check flow, we had one site that had a continuous enable signal but no flow, hence all the oil was pumped out of the resevoir and the unit would fault on low oil level.

just a long winded example of what may eventually happen if your maintenance guys keep doing this, then again running the pump keeps the shaft seal lubricated!!:p

Alec

the york chillers ran the aux oil pump for a time pre and during start up and for a period during shut down some tradesmen charged the chillers with oil using the auxillary oil pump but my "old school tradesman" was stirrup pump only saying it was the only way to get a proper oil level that was a LONG time ago!

My thought process says that oil doesn't migrate unless another medium takes it away (refrigerant) or it leaves by gravity flow.

I agree with some of the others here who go with the pre-lube theory.

on a centrif the oil cicuit is not 100 % tight some oil will be discharged into the ref circuit with just the pump running so if you have a job where the bas is starting/stopping the chiller alot you may not have enough run time for the oil recovery system to return oil to the sump.