404a and 507

[kepons]

Hi!
I'd like to know why R404a can't be used with mineral oil while 507 can be with small amounts of R290 added for oil movement? Is it because of R134a added to 404a or what?

Regards,
Kepons

[WINJA]

isceon 49 contains r134a and can be used with straight mineral oil , I could only conclude that the r134a was diluted enough not to break down the oil, i came across a
frascold semi hermatic recip compressor which had mineral oil in it and it was on 404a it ran ok for about a year before the error was picked up, I changed the oil which looked burnt
orange colour put in poe and it runs fine

[750 Valve]

Hi!
I'd like to know why R404a can't be used with mineral oil while 507 can be with small amounts of R290 added for oil movement? Is it because of R134a added to 404a or what?

Regards,
Kepons

I've never heard of this before - adding r290 to R507... how much do you add? I'm a bit suspect on this practice, why would it not be possible to change the oil to POE?

Incidently, the first large commercial retrofit to R134a that took place in Australia was on a pub and club system that ran flooded low side vessels for beverage coolers (temprites), the 134a was added and the mineral oil retained as it was too large a task to remove all the mineral oil, actually it was impossible due to a temprite's design - low side float, and although a few issues were noted with the temprites, the plant ran for approx 8 to 10 years before being ripped out on a refurbishment of the club. There were no oil issues as no oil was lost, as it wasn't miscible it did not get past the oil separator and was returned to the compressor.