R134a -why POE?

[phil68]

I've learnt a few things since joining this forum, most recently the fact that R134a was invented back in the 1930's a couple of years after R12, by the same bloke, which was a bit of an eye-opener for me as I thought it was invented quickly to take over from R12 in the early 90's. My question is why do we need to use POE oil with R134a as it didn't exist back in the 30's & I'm a bit of a sceptic

[old gas bottle]

1930,s ? is that right, along a similar line,is it also true that mineral oil was used in conjuction with R404A in the early days,i have come accross this more than once.

[Johnny Rod]

I believe it's because mineral oil won't dissolve appreciably in R134a - you'd get problems with oil return. The oil dissolves in the liquid refrigerant, but also gets blown along by vapour. The easier it dissolves the easier it gets back to the comp.

Don't know who invented what when but if oyu had the choice of R134a and R12 I don't think I need to ask which you'd go for. Presumably in the 30s they just used whatever oil there was and figured out ways around the problems.

[rbartlett]

or maybe they waited for 60 years for the right oil to be manufacturered?

cheers

richard

[John Wood]

If you ever have the misfortune to come accross a system charged with R134a and mineral oil you will find it has low suction temperature and low suction superheat. The oil will have turned to vaseline inside the evaporator and virtually stopped any heat exchange. There is a cure, recover the refrigerant and recharge with R413a.
Early R134a systems all used pag oil (cars still do) polyolester was used slightly later, but rapidly adopted because it is less carcinogenic and will mix with mineral oil and R12, allowing retrofitting.
Hope this helps.

[D.D.KORANNE]

Probably It Has The Rigt Mix Of Chemistry !

D.d.koranne

[monkey spanners]

Back when retrofits were all the go, i made up a short piece 1 1/8" pipe with a piece of 3/8" in one end with a sight glass and shraeder valve, put some mineral oil in vac out and charged a small amount of R134a into it. the two fluids never mixed and when shook up would go cloudy/milky. Nothing like seeing it for yourself. When we used to do a lot of retrofits we would sometimes find a yellow enamel type deposit on the sump plug, guys from castrol said it was sulpher from poorly refined mineral oil. We used to have a customer with a frigidare open drive that he ran on duckhams engine oil (green one) because the shaft seal leaked and the previous engineer had told him to use it as it was thicker! Can't remember how well it worked as i was six or seven at the time.
cheers Jon