COMPRESSOR RENEWAL-OIL CHANGE REQUIRED (R22 to R407C).

[Daikin=Overated]

My first post in some time, so I should start by saying hello again to you all. I'm a big fan of the site, and appreciate everybodies contributions, of which I've learnt so much from :)

I have a question regarding a failed Bristol compressor in a Hitecsu ducted condensing unit. Essentially it's seized and needs replacement.

The manufacturers have advised that there is no direct replacement available due to the exisiting Bristol pot being R22 which I can understand. They have come up with a replacement R407c Bristol compressor that physically is identical, only the oil would require changing from Esther (spelling?) to Mineral oil avoid contamination.

I need to get the oil replaced to within 5% appartantly, but how? Am I to simply turn the compressor upside down and drain the old oil out-if so any tips ( I was thinking of weighing it out to know how much to put back in). Do I need to flush through with any specific product, and would I need to prove conclusively with some sort of test kit that the oil is within 5%?????

Final question, could there be a further need to pump the oil manually through the suction side of the system, theres no oil site level glass, only I'll need to invest in a pump if so.:D

Cheers in advance.

[BigJon3475]

I think your oils are backwards. POE should be used with 407c. 5% refers to the maximum amount allowed to be within the specs for POE oil.


From DuPont:

"When converting a CFC system to an HFC refrigerant
(Suva® 134a, HP62, 507, 407C, or 95), POE is the
recommended lubricant. At least 95% of the MO, or AB
should be replaced with POE of similar viscosity. This
typically requires multiple oil changes."

http://www.refron.com/InfoCenter/TechData/DuPont_Replacement_Guide.pdf


This info may be useful to you .....then again maybe not good luck.

[Brian_UK]

One way to check the oil out of a sealed pot is to very carefully drill a hole at the base of the pot. Start with a small drill and work up to the final size required.

The oil inside should push any swarf out of the hole.

You could then flush the oil using the the suction stub as a fill point.

When you're ahppy that the unwanted oil is gone you can either braze the drilled hole over or braze in an access fitting for future draining/testing etc.

[monkey spanners]

Hi

If its a reciprocating compressor or a scroll and not too heavy i usually tip the oil out the suction connection into a jug and then tip the same amount back in. If its a big one you can feed some small bore silione pipe (model car/plane type fuel hose, model shop) down into the sump and suck it out, either with a large syringe or a conveted disposeable refrigerant bottle, and again put back what came out.
Ester oil is compatable with R22, R12 andR502, so i'm not sure you even need to change it, unless other parts of the system and incompatable( solenoids, seals, gaskets etc)
All the CFC/HCFC to HFC conversions rely on using ester oil with the existing CFC/HCFC and four or so oil changes to flush the old oil out to allow the refrigerant to be changed, so you would in effect have a first stage of a conversion in the system. Maybe the wholesalers are unsure and are being cautious. This is just my opinion, you must make your own mind up;)

[Thermatech]

You need to get hold of a Refractrometer.
Basically every type of oil has a refractive index which you can see as part of the oil specification.
For example if you took a reading of 20/50 engine oil you would get a refractive index reading but if you then took another for say... cooking oil you would then get a completely diferent reading.
1/ So first take a reading with the refractrometer for virgin mineral oil then take a reading for virgin POE synthetic oil. Note these readings & divide by 100. Then for any given mixture you can calculate the % mix. Really 5% is only just about readable on the refractrometer scale.
2/ After the systems been running for a few days any old mineral oil should be mixed with the new synthetic oil. A sample of this mixture will give a reading between the two virgin samples.
3/ Drain down & replace with new synthetic oil & let system run for a few more days.
You will see an improvement in the mixture each time you change the oil untill the mixture reading is just about the same as the virgin synthetic oil.
Replace the oil in the compressor by drilling a hole at the bottom & braze in a 1/4 service port to carry out the oil changes & use an oil pump to refill.
Because there is no sight glass you need to very carefully measure the volume of oil removed & replace with exact volume of new oil at each oil change.
You need the correct model refractrometer because there are many types for different applications.for example Bee keepers use them for measuring honey.
Got my refractrometer from HRP but that was about 11 years ago when we first started retrofitting the hated 407c.
If you do not get down to 5% the system can eventually get clogged up with sludge & your into replacing the complete system.

Happy oil changing.

[Daikin=Overated]

Many thanks to all of you above who have replied, that's plenty of food for thought to keep me going on.
All the best!

[Naqee]

Thanks dude i registered this site for this post! I love it