oil/refrigerant acidity

[Collie]

Question: Is it possible for the oil the fridge circuit of a chiller to be contaminated and acidic but the gas to remain ok?
I would assume that by carrying out an acidity test on the refrigerant it would pick up if the oil is acidic also as there would be oil entrained in the gas? Is this a correct assunption to make, any ideas?

[goshen]

what is the case here?

[R. skiffington]

Standard practce would be to carry out an acid test on the oil not the refrigerant, acid test kit are readily available at any refrig supplier. If your Oil is acidic obviously you'd want to change the oil, it would be good practce to replace the refrigerant charge aswell then retest the oil in a week or so, if still acidic, change the oil again and introduce acid neutraliser. Keep re checking until the oil is safe (remember to change drier cores)

[lowcool]

whats acid neutraliser?

[Collie]

Well, the compressor originally was shorting to earth from the windings so it was taken out and repaired. I didnt notice the harsh sulphuric smell you get when the oil is contaminated so I didnt fit a burn-out drier. We refit the compressor using new gas and new oil and it ran away fine for a few weeks but now the winding is shorting to earth again. I tested the refrigerant its ok. I used a Virginia ETK acid test kit on the oil, I followed the instructions. The test bottle was very cloudy abd I had to hold the bottle up to the light to see a colour, as you would do maybe with a glass of coca-cola to see its redish colour. According to the colour chart with the kit, the oil checks out ok, but I'm a little worried, should it be difficult to see the colour of the oil mix in the test bottle? Having left the bottle now for nearly a week the colour has changed but I dont think its of any relevance, its a 10-15 second test kit. I'm worried that the compressor has faulted due to something I've done or failed to do. Any more thoughts? thanks guys

[Yuri B.]

Hello.The motor (windings) of a compressor can burn of a hundred+ causes. It seems you have concentrated all your attention just on the acidity. Is EVERYTHING besides it all right?

[Collie]

What kind of checks can you recommend? I know that it was wired correctly, so I'm stuck as to where to go from here?

[Yuri B.]

Hello Collie.
Maybe a coinsidence, and the motor's rewound was of low-quality (such as varnish used incompatible with the refrigerant)?
Anyway you have given very little info.
All safety devices present and set correct?
What refrigerant is used?
What the type of unit is it at all?
What were pressures, temp-s, temp deltas, SH, subcooling, voltage, Current?
Crankcase heater ? Oil return? Fans? etc.

[Sledge]

Assuming that the repair to the compressor was good, new gas and new oil I think the trouble is with the power supply.

I have encountered this before. There were 2 Berg chillers cooling a water loop used to cool the welding tips for spot welding bumpers. Both chillers had rebuilt compressors, yet the chillers themselves were only 2 years old. I should have seen the signs but missed them. I changed the compressor, and turned it on, it failed immediately. I checked the power supply and my meter blew up. I had another, high quality meter in the truck and tried that one. I found that the normal power supply of 3 phase 600 volts (347v to ground) was now reading 1400 volts to ground. This lasted for about 10 minutes and then disappearred. I was unable to prove it and ended up having to change the compressor under warranty. 6 months later I met the former plant engineer at his new place of employ, and he revealed to me that the problem was caused by a short in a spot welder in the plant. Improper grounding allowed the voltage spike to find its ground through the compressor. They blew up a lot of stuff before it was identified.

I would install some kind of 3 phase protection module...unfortunately any that I know of will not detect balanced overvoltage, only phase imbalances. I would also monitor the power supply voltage with some kind of voltage recorder.

[tonyhavcr]

Well, the compressor originally was shorting to earth from the windings so it was taken out and repaired. I didnt notice the harsh sulphuric smell you get when the oil is contaminated so I didnt fit a burn-out drier. We refit the compressor using new gas and new oil and it ran away fine for a few weeks but now the winding is shorting to earth again. I tested the refrigerant its ok. I used a Virginia ETK acid test kit on the oil, I followed the instructions. The test bottle was very cloudy abd I had to hold the bottle up to the light to see a colour, as you would do maybe with a glass of coca-cola to see its redish colour. According to the colour chart with the kit, the oil checks out ok, but I'm a little worried, should it be difficult to see the colour of the oil mix in the test bottle? Having left the bottle now for nearly a week the colour has changed but I dont think its of any relevance, its a 10-15 second test kit. I'm worried that the compressor has faulted due to something I've done or failed to do. Any more thoughts? thanks guys


Hi Collie I think of all shorts to ground to be burns some just worst then others, on a vary bad burn I had to change after 1hr then 1 day then 1 month to clean it. I never use acid neutraliser just oil gas and dryer changes I have seen others lose a compressor after changing from poor clean up
(skiffington Re: oil/refrigerant acidity
Standard practce would be to carry out an acid test on the oil not the refrigerant, acid test kit are readily available at any refrig supplier. If your Oil is acidic obviously you'd want to change the oil, it would be good practce to replace the refrigerant charge aswell then retest the oil in a week or so, if still acidic, change the oil again and Keep re checking until the oil is safe (remember to change drier cores)

When you put the next one in I would use nitrogen and blow out any oil in condenser, then evaporator see what you get ? read refrigeration 101 so you can rule your system out. This will leave electrical to test I would all ways change a contactor with a compressor. If you do it step by step you will be able to post more info from what you find

[D.D.KORANNE]

Flushing with n2 the system, replacing oil several times until oil is free of acid , change of core are a must . But it has to be identified why the oil is becoming acidic. High discharge end temp , high superheat, fouled condenser , air in system etc need to be looked at. Basic issue to be addressed .

[Collie]

wow, great stuff guys thanks for the responses. sorry for the lack of temps, pressures etc., its just that I wasnt around when it was running, only now that its died :confused: have I been called in.
RE: Sledge. Hey, come to think of it, while i was wiring it up after the comp went back in after the first rewind, i was wedged between it and the compressor next to it, and at some point i reached out to push myself up and I got a shock, 230vAC. I had just assumed I had touched of a terminal in the compressor beside me but now that Im thinking of I dont think I was near any terminals. There maybe a leakage problem. I'll look into all the advice guys thanks alot:)

[ptsac]

Hi collie,
have the contactors been replaced, a fault current can do some damage to contact points.

[tonyhavcr]

Flushing with n2 the system, replacing oil several times until oil is free of acid , change of core are a must . But it has to be identified why the oil is becoming acidic. High discharge end temp , high superheat, fouled condenser , air in system etc need to be looked at. Basic issue to be addressed .


I got called to do a job where some one replaced a large
compressor 4 times ea. time it lasted less and less I found it was vary poor clean up the slug that came out the condenser all I will say is wow, plus I got a lot of oil out from all the past compressor that failed.

[Fri3Oil System]

Hi,

If you really want to be sure that you have eliminated all acids not only from the circuit, you have to use the correct technology, which is today available.

There is a system that enables you to recover and recycle on site any halocarbon refrigerant, and, with this refrigerant, flush/recirculate the plant/installation until you have extrated all oils + acids, til the last drop.
Using N2 will NOT eliminate the acids, since it is not miscible or solluble with them, AT ALL. So if you have changed the compressor, the next one will burn as well.
BY the way, this technology allows you to recycle and reuse the refrigerant afterwards... which a money saving, isn't it