mixing refrigerant

[mondofromredondo]

Hi all,
I have a 20 year old Adler-Barbour refrigeration system.
I have to replace the condenser / compressor unit so when I disconnect the cold plate it will leave the old style refrigerant in the cold plate. So when I connect the new condenser / compressor unit loaded with the new stuff will that be a problem?

Thanks,
Keith

[captbillc]

search google ----- mixing refrigerants----you will find a lot of information about it there

[billyruffn]

You will probably need a refrig mechanic to help....you will need to pull a vacumn in the system to get all the old gas and any air out before the new gas goes in. There's also the issue of gas-compressor oil compatability. You may have a R-12 freon system and the oil in it will not work with the newer gases.

[EO32]

From what I've heard, the compressor oil in a R-12 system will turn to goo if you put R-134a in. I would think all of the advice given is correct.

With that said, when my 12volt AB didn't work, instead of spending $900 on a new compressor unit, I cut off the old compressor and brazed one on that I cut off an old R-134a 110vac mini fridge, added a filler plug and filled it with R-134a. It's been running for the last year on shorepower/inverter for the last year without any problems.

[JimsCAL]

DON'T MIX REFRIGERANTS!!! Remove the old refrigerant (probably R-12) from the cold plate. Technically it should be "recovered" by an EPA certified technician as R-12 is controlled substance which destroys the ozone layer and cannot legally be vented to the atmosphere. The new compressor unit will probably come pre-charged with R-134a and will have the proper oil as well. The small amount of "old" oil in the cold plate shouldn't be a problem.

[theartfuldodger]

If by chance you can remove all the R-12 you can recharge with the 134A you will also have to change up the oil to one which will be compatible with the old parts. One more thing the R-12 mixed with any tpye of flame is nerve gas the reason for the mention is people have been known to use a propane torch to heat up fittings so they can get them free. Best to have a licensed person do the work.

[captbillc]

johnsen's freeze 12 is supposed to be compatible with R12 & the oil in an R12 system. check it out on google. this looks like an easer way to go.

[captbillc]

you would have to get the 134A out of the new parts first & pull a vacuum on the system.

[denby]

It's not so much a refrigerant problem as a oil problem. The R-12 system used a mineral oil, probably 3Gs oil, the new system uses a man made oil, probably polyoester oil. If the two oils are mixed you get tar and the system is destroyed, the evaporator needs to be cleaned out with the proper cleaner first, then you can install the new condensing unit.

PS, I'm in the commercial and industrial refrigeration business.

[billyruffn]

Originally Posted by denby

It's not so much a refrigerant problem as a oil problem. The R-12 system used a mineral oil, probably 3Gs oil, the new system uses a man made oil, probably polyoester oil. If the two oils are mixed you get tar and the system is destroyed, the evaporator needs to be cleaned out with the proper cleaner first, then you can install the new condensing unit.

PS, I'm in the commercial and industrial refrigeration business.

Question for you Denby (with apologies for hijacking the thread, but the question is related to the topic of the OP):

How difficult is it to convert an R12 system to an R134 system?

I have two independent refrig systems on BR: one for the frig, the other for the freezer. The only difference between the systems is the size of the box. Five years ago in the Caribbean I had a new system installed -- call that system #2. I asked the refer mechanic to install system #2 with R-12 because I had another R12 system (call that one #1) aboard and the mechanic advised R12 was more efficient and I'm all for minimizing genset operating hours. (Before the greenies get on my case, I know, R12 kills ozone, but gensets burn diesel and that causes global warming ---- so what's a tree hugger to do????)

The refer guy said he could drain the oil that came with the compressor and install R12 compatible oil. He did and it's worked well ever since. Now the old R12 system (#1) has failed and I will need to replace it. Because we're in the US we can't / won't get an R12 replacement. So system #1 will probably be R 134 and as I would like both systems on the same gas, system #2 needs to be converted from R12 back to R134.

Question: how hard is it to get all the R12 oil out of the compressor so that it can be replaced with an R134 compatible oil? What are the economically reasonable options for dealing with this situation?