dark vader refeigeration oil

[greg56]

I am in the process of cleaning up a system that has very dark oil... It is a 25 ton condensing unit,air cooled, which is matched up with equal sized chiller barrel....( york equipment about 15- 20 yrs old)I have installed new l.l. drier and suction core drier . I have changed the oil out of the crank(Semi-hermetic ) 2 times utilizing a manual oil pump.also i have changed the core 2 times already. works good but seems i am going to have to repeat this process many more times to obtain clean oil... Does anyone make or know of a method to do a "dialysis" on systems? I have read a couple of threads on a transfer pump but this is not a big enough system to justify the expense... any help? let me know... greg ;)

[The MG Pony]

could you make a simple system from some old parts laying about?

a rotary vane pump to bleed off the oil and push it through an ultrafine filter or such?

[monkey spanners]

Hi Greg,

I found some black oil in a prestcold 3hp compressor when i was changing the oil level sight glass after it developed a leak.
After a few months it was nearly as dark again, i think this is due to the fact that the valve plate on this compressor doesn't seal very well which results in the discharge temperature being a bit too high.
Unless you find and fix the cause of the discolouration it'll be back to black in a few months.
I think burnout driers (HH cores) are best for cleaning up this sort of contamination.

Cheers Jon:)

[Peter_1]

How I charge big quantities of oil: pour the oil in an old (or new :) ) liquid receiver after unscrewing the rotalock where the liquid enters the receiver.
Screw back the rotalock tight and vacuum the cylinder to remove air above the oil.
Connect outlet of receiver to the sump with a liquid line drier between it.

Pressurize receiver with the same refrigerant as the system.
I'm pretty sure that if the oil isn't acid (acid tester) you can re-use the oil and the particles in the oil will remain in the drier. Due to the big pressure difference, you don't have to apply manual force to add the oil.