R22 Foaming reciprocating compressor crankcase oil

[RANGER1]

Have a question on oil "foaming".
What could be considered normal in real life practical terms.
Why does it foam?

Any good articles or previous posts appreciated.

Thanks in advance

[martinw58]

it may be refrigerant in the oil is the oil heater working

[chemi-cool]

refrigeration oil can not foam on its own, it needs an other substance to foam.

When liquid refrigerant gets into the oil in the compressor sump, it boils and what we call "foaming" are the refrigerant liquid bubbles that goes up and out of the oil.
Time to check why refrigerant liquid return to the compressor.It shouldn't.

[Steve186]

Is this an 06e compressor by an chance
Carrier flowtronic

[Glenn Moore]

Hi Ranger
Please pm your email and I’ll send you some articles on why compressors fail which explains this foaming or I think their still on the Danfoss web site . I wrote them due to the amount of Maneurop compressors I was getting back under warranty when they were obvious site issues

[RANGER1]

Glenn, thanks, sent you email.

[mbc]

Hi
Refrigerant slove in the oil and when comparssor is start pressure comes down and gas goes to bubbleing inside oil

To solve that we use heater to warm up oil and decrease refrigerant in oil

[Steve186]

Hi Ranger
When CFC/HCFC refrigerants are used with Mineral or Alkylbenzene Oils, foam in the sight glass normally indicates
serious liquid flood back or the running gear is hitting the oil due to a very high oil level
very high oil level can be due to either too much oil or excessive liquid refrigerant in the crankcase
what i would do is carry out 2 or 3 pump downs to remove any liquid refrigerant in the crankcase
then recording the suction pressure and suction super heat and crankcase temperature at 100% RLA
this will confirm if the circuit is flooding back.
Also its possible that the incorrect oil has been used this would cause foaming

not teaching you how to suck eggs Ranger as you appear to be a very competent engineer
but ive had this issue many times on the 06E Compressors causing oil pressure issues due to liquid flood back


this will indicate if the circuit is flooding back or not

[RANGER1]

Thanks for responses.
In this case industrial compressor
synthetic oil
oil temperature in crankcase 45 to 50 degC
SST -10 deg C
sometimes foam on top of oil, if loads up or suction pressure suddenly drops all oil foams.
oil pressure always good.
flooded evaporator on R22
Cylinder banks warm under/ around heads.

discharge temperature 65 to 70 deg C

All seems normal to me, others say floodback

If liquid in sump, thought oil temperature would drop, oil pressure fluctuate, or trip on low oil pressure.
Discharge would be cooler.
Maybe I’m in denial

[seanf]

Would liquid coming through the oil seperator cause it to be less effected by the warm oil temp?

[RANGER1]

Would liquid coming through the oil seperator cause it to be less effected by the warm oil temp?

Seanf,
Thanks, I don't think oil separator oil return is an issue in this case, as it returns to pilot oil reservoir that is vented to a lower pressure.
Oil return from oil separator can be an issue if discharge check valve leaks & condensed refrigerant ends up in oil separator in off cycle.
If there was refrigerant in oil separator you would notice it expanding with refrigeration effect through oil return float.
Open to any ideas, or theories.

[seanf]

Are you able to prove its not floodback?

Would oil analysis be able to tell you anything? do refrigerant oils have anti foaming agents? is it actually the right oil?

[seanf]

Don't think it would be likely but. What if the oil separators valve is stuck open bubbling discharge gas into the cooler oil in the reservoir (a high level or inlet normally below the oil level).