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QQQ
09-07-2003, 05:54 PM
The screw compressor has stopped on a low level of oil.
(Chiller of climatic application(R22))
Please educate under What conditions the oil is carried away
and, most important,
How it to return back???
Kind health all!

Dan
10-07-2003, 04:26 AM
Hello, QQQ.

Is the low level an actual level control or is it a flow switch? What sort of oil separator is installed?

Oil return problems are very difficult to diagnose without tremendous amounts of information.

It is nice to hear from somebody in Russia. Now the honeymoon is over.:)

1. What compressor system do you have?
2. Is it a refrigeration or air-conditioning application?
3. If it is air-conditioning, does it use a secondary refrigerant (glycol, for example)?
4. How long has it been in operation?
5. When does the oil failure happen?
6. Can you tell us anything more about this system?

I will stop there. I think you have some ideas what the problem could be.

QQQ
10-07-2003, 04:46 AM
Hi Dan
-Is applied flow switch
-oil separator not installed
1. HARTFORD
2. air-conditioning application
3. use a secondary refrigerant
4. I think one day (in abnormal conditions)
5. Yesterday in afternoon
6.Two-circuit chiller (7C - 12Ñ)
Air cooling 750000 BTU/h

Andy
10-07-2003, 03:38 PM
Hi QQQ,:)
More questions:-

What way is your oil cooled?
Is your refrigerant charge adequate?
Is the condensing conditions above normal?

Kind regards. Andy
:)

Dan
11-07-2003, 04:45 AM
There has to be an oil separator. Perhaps it is indigenous to the compressor? What does "Two-circuit chiller (7C - 12Ñ)" mean?

QQQ
11-07-2003, 03:54 PM
HI DAN!
HI ANDY!
You are absolutely right, is present internal oil separator.
I wanted to say - two independent refrigerating systems in one box,
on standard conditions 44F - 49F.
For restoration of system I perform the following actions:
1. Loaded oil into the compressor for removal of a protection's signal
( Approximately 4kg)
2. Manually start and load up the compressor about 40%.
3. After two hours I have drainage out 2kg oil.
4. Further I have increased loading up to 65 %.
5. After one hour I have stopped the machine,and drainage out 2kg oil
again.The level of oil has come in a normal condition,
It is visible on sight glass.
6.At last I have switched on the machine in automatic control.
Now system run okey.
I'll to find out How there could be such damage.
If there are any ideas please inform.
Large thanks for moral support.
Best regards!

Dan
12-07-2003, 02:08 AM
Andy, QQQ seems to be pretty sharp. Where do we go next? Risers are a thought, among a thousand others.

QQQ, your measurements are indicating a failure to return oil, but they could also be indicating a failure to capture the oil in the separator. Andy knows screws much better than I do, so let's both enjoy his questions together.

Andy
12-07-2003, 09:47 PM
Hi QQQ:)
If you overheat a screw the oil thins and is carried around the system. Let the compressor cool down add oil then run, removing oil as it returns.
I would check you oil cooling a peak (summer type) loading.
First establish what type of oil cooling used.
I would suspect liquid injection, if anything.
Then check it's effectiveness by measuring the compressor discharge temperature. (for water chilling this should be below 70deg C) if not you may have a problem.
Regards. Andy:)

FreezerGeezer
14-07-2003, 12:30 PM
This reminds me of an occasion when 3 APV screw packs lost their oil around the system. It was the middle of summer, and someone thought they'd be helpful & prop the plant room doors open 'to keep the plant cool'!
Well, the oil thinned, just as Andy says, and we had to do just what QQQ says he did to get the packs running again. You can imagine the supermarket's panic when the refrigeration for the entire store shut down!