Carrier chiller oil migration

I am new here and already looking for some help. I hope this is in the right place.

I'm working on a 30gb200-600 Serial X396113 Carrier liquid chiller, air cooled. It's an 83 model. Each of the two circuits is made up of four 275 compressors. Each side has one liquid line and two suction lines branching into four suction lines going to the compressors. This unit does not have the big oil equalizer lines out of the sight glass holes. It does have the 1/4" pressure equalizing lines out of the bottom of the compressor motor barrel connecting all four compressors together.

Circuit 2 only has compressor 2 & 4 running at this time. Before I started the unit up I adjusted the oil levels to the recommended bottom of sight glass to 3/8 of sight glass as usual for the 06E short stroke compressors. After several hours of running the oil in the non running #6 & #8 compressor has migrated down to the running #2 & #4 compressors. The oil level reached the point that I need to drain some out to avoid valve damage I think.

Can someone please help me out with what's going on? I thought the small 1/4" pressure equalizing lines were supposed to keep the suction pressure equal between the operating and the non operating compressors to keep the oil from migrating. What's happening? What can I do to stop it?

I don't have any manuals on this old machine. I'm not a Carrier dealer and have to rely on Mingledorff, my local carrier distributor for literature and they can't seem to find anything this old. Does anyone have a link to a control and operation manual?

Quote:

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Originally Posted by lowtech

I am new here and already looking for some help. I hope this is in the right place.

I'm working on a 30gb200-600 Serial X396113 Carrier liquid chiller, air cooled. It's an 83 model. Each of the two circuits is made up of four 275 compressors. Each side has one liquid line and two suction lines branching into four suction lines going to the compressors. This unit does not have the big oil equalizer lines out of the sight glass holes. It does have the 1/4" pressure equalizing lines out of the bottom of the compressor motor barrel connecting all four compressors together.

Circuit 2 only has compressor 2 & 4 running at this time. Before I started the unit up I adjusted the oil levels to the recommended bottom of sight glass to 3/8 of sight glass as usual for the 06E short stroke compressors. After several hours of running the oil in the non running #6 & #8 compressor has migrated down to the running #2 & #4 compressors. The oil level reached the point that I need to drain some out to avoid valve damage I think.

Can someone please help me out with what's going on? I thought the small 1/4" pressure equalizing lines were supposed to keep the suction pressure equal between the operating and the non operating compressors to keep the oil from migrating. What's happening? What can I do to stop it?

I don't have any manuals on this old machine. I'm not a Carrier dealer and have to rely on Mingledorff, my local carrier distributor for literature and they can't seem to find anything this old. Does anyone have a link to a control and operation manual?

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go here

http://www.xpedio.carrier.com/idc/gr.../?SMSESSION=NO

cheers

richard

Quote by Lowtech
I am new here and already looking for some help. I hope this is in the right place.

After several hours of running the oil in the non running #6 & #8 compressor has migrated down to the running #2 & #4 compressors. The oil level reached the point that I need to drain some out to avoid valve damage I think.

Can someone please help me out with what's going on? I thought the small 1/4" pressure equalizing lines were supposed to keep the suction pressure equal between the operating and the non operating compressors to keep the oil from migrating. What's happening? What can I do to stop it?


The oil is being sucked out by the running machines. If you can even out the run hours the oil levels will sort themselves:)

Larger bore connections, especially above the oil level will help, the idea set up would be a branch header connecting all the sightglasses, with the same diameter as the sight glasses, with new sightglasses fitted on the header.

Best of luck:D

Kind Regards. Andy:)

I seen that problem on heaps of Carrier air cooled chillers , I wouldnt worry about it to much excessive oil levels are only a real problem once the oil level reaches the crank shaft bearings as the refrigerant in the oil washes the oil out and destroys the white metal of the bearings. You could try running a larger equilizer between the crank cases , but correct oil charge is fairly crictical so just trim the oil charge until your happy.
As said correct compressor staging will help.h

Lowtech,
Early 30GB and larger capacity 30GT chillers generally had a large oil equalisation pipe from each sight glass which worked fine through all loading stages, but was a pain when changing out a compressor or doing repairs, isolation valves / flanges between each compressor with sight glasses can resolve this, if the client is happy to pay.

From memory, Carrier did this model on the cheap as there was only two oil failure switches per unit - one on each lead compressor on each circuit. So much for the lag ones.

Cheers

Hi Lowtech, check the oil equalization check valve installed in the rotor locking bolt in each of the compressors. You can check the valves by removing the suction filters on the compressors. I hope this helps. Dimitris