Printable View
Hi
Was asked to have a look at a mates fridge in his pub kitchen, its an old fosters no date on the label but running off R12(so round about 1995 i guess) anyway fridge had been worked on in the past (apparent regas!!) 18 months ago. put my gauges on and their is no pressure but compressor pulls a slight vac.
When it was regassed would it have been done with R12 18 months ago? OR was it 134a if so the compressor would not have lasted this long OR WOULD IT? :)
No in short R12 went long before that might have been a drop in
But how long would a compressor last running off 134 if it was designed for r12 in a fridge with cappilary tube. would it fail because of the lack of ludrication in the compressor or would there be other reasons?
The problem is with the mineral oil used in R12 comps as its isn't soluable in R134a.Quote:
Originally Posted by bob007
It is most likely that a 'drop in' refrigerant such as R413A/R437A/R409A etc has been used, these are generally a mixture of R134a, another refrigerant and propane,butane. The propane/butane is what brings the oil back as it mixes ok with mineral oil.
The compressor would most likely be ok with R134a, but not with a lack of oil return or blockages in the system.
Jon :)
Thanks for that monkey spanner, i knew the oil and lubrication would be the problem but wondered how long it would run for, its as old as the hills and thought if i used 134 it could get them through the next 3 months till they buy some new kit.
thanks
I don't know how long it would work for, i would not be surprised if it failed within a day or so.
I have heard of R134a being used in R600a fridges without problems but i suspect that the residual R600a in the oil helps bring the oil back, but its just a gut feeling, nothing technical.
oil change in compressor required..........mineral to polyolester, even if you think it has already been done do it again then if the comp is still a runner give it a long vacuum after finding where and if the charge fell out of course, if there is still any residual refrigerant in the system you may also consider adding an acid neutalizer............enjoy.......Quote:
Originally Posted by bob007
I know this is a big bump. but you guys in the uK haven't heard of sp34e?
Hell I haven't seen it for ages, but basically it was 97% R134a and 3% propane. It was around in australia for ages, the little bit of propane sorted out the mineral oil compatibilty.
It was a straight drop in. R134a doesn't hate mineral oil, it just doesn't transport it very well.
It's hard to say how long systems ran on sp34e, most systems obviously were very old when changing refrigerant.
But also at the same time, I was involved in many full retrofits with oil changes and flushes, valve and seal changes and testing, and I can say they for sure they didn't last very long before leaks etc either. SP34e was 2 years too late for me, but surprised it didn't become retrofit standard and no one bother with full change overs. Unless you guys have heard of it and there was a big problem I didn't hang around long enough in the commercial world to hear about
Do you really think a 3% of the blend can bring all MO to the compressor?Quote:
Originally Posted by paul_h
You should ask in Renault's Factory in Sevilla, Spain, they have broken above 30 compressors since they decided to brilliantly retrofit to R417 and no oil change...(it's more or less the same blend, around 3% of butane-propane)
regards,
Nando.
Quote:
Originally Posted by paul_h
As said, just asking because it seems to be unpopular, and I've long ago stopped working on such systems. It was a question.Quote:
Originally Posted by Fri3Oil System
:) Sure :) I was just informing :)
Maybe reclaimed refrigerant, you can use R134 if the oil was flushed.
You can use a 60-40 propane and butane mix. It's a direct replacement. Charge HALF the weight of R12. It would work okay with both oils
If you want you can cut about half the capilary and use only R600 (butane). It's much more efficient (that's what A class fridges use these days);)
I have come across 134a in r12 fosters units before , working well over 3 years since having it put in as a drop in . Also 409a and even R22 but the 134a is still in there and working well. The only issue is the oil obviously but replacing with ester solves the prob. If its only short term then flip a coin but have known short term turn into years. ;)