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AOBB
18-11-2007, 01:07 PM
Does any one know a suitable way to change the refrigerant from a CFC/HCFC to a transitional zeotropic blended refrigerant that is miscible with mineral oil? thanks:confused:

Argus
18-11-2007, 02:08 PM
.

There’s no one-part answer to your question.

First you decide on the refrigerants that you want to use. Most HFC blends, and most of the HC blends are zeotropes.

Using existing mineral oils reduces your choice of refrigerant somewhat, as most of the new HFC blends need synthetic oils.

You will then need to check that the chosen refrigerant is approved by the equipment manufacturer, as changes may voids warranties. Then consider changes to the circuit to make it compatible – TXVs, condensing controls, etc.

The manufacturers of the refrigerant will offer suggestions about refrigerant changing techniques and they should also reflect the type of system that you are converting.

Finally, the old reclaimed refrigerant and oils are now, legally speaking, Hazardous Waste. Depending where you are located, you and your customer are both covered by the new Hazardous Waste regulations.

.

TXiceman
18-11-2007, 05:55 PM
If you want a zeotropic refrigerant, look at the 500 series. All of the 400 series are blends.

I would not run a mineral oil in any of the newer refrigerants. You will need a POE or POA oil for the various refrigerants.

There are a few specialty blends that claim to operate with mineral oil and you will just need to go to the manufacturers site and read about the change out procedure.

Ken

fridg
19-11-2007, 08:07 AM
this is a good point to remember



old refrigerants will work with new oils.


new refrigerants will not work with old oils.

Chris Burton
13-12-2007, 08:44 PM
I would'nt use mix synthetic oils with the old CFC's on recips, they are so miscible together i had a lot of problems with increased bearing wear due to poor lubrication:(

Grizzly
14-12-2007, 12:01 AM
Chris.
Your bearing wear may of been occuring for a slightly different reason than you think.
When I was Site Engineer for a large Cold Storage Group.
A National agreement was struck with Mobil. All 35 stores changed from Shell Clavus 68 to the sythetic
"Arctic" series of oils.
All was well apart from the fact that I started to have to change my shaft seals more often and we changed the oil more often. As for a while it was bringing back old mineral oil mixed with it.
Anyway for some other reason a lot of us got together and whilst talking about "issues" realised that these issues were not isolated. When it was looked into further, it was discovered that.
The new oils had a cleaning action. ( Have you ever
wiped up spilt synthetic oil from the floor, to find the spilt area cleaner than the surrounding area?)
And all the pipework etc was being cleaned and flushed through. This "mix" was wearing out the optical surfaces on the shaft seals. Also certain "o" rings seemed to fail more often. Filters would fail more often and oil pressure / lubrication issues occured.
Anyways after about 2 years everything returned to normal. And a much cleaner and stable system was observed
More importantly you can run the newer oils with R22. But as it will be redundant shortly, I am not sure wether it's relevant anymore.
ONE fact is relevant though when considering what new or replacement refrigerant to use.
You have GOT TO concider what oil is going to be used with it and what traces of what oil will still be in it?
Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif

thermo prince
14-12-2007, 05:32 AM
Grizzly makes good points above.

The POE oils with HFC's likewise are noted for their 'scouring' action on the inside of cu tubing and will bring a lot of crud back to the compressor.

In early days of the HFC changeover, Westinghouse (W)STC did a lot of research on lubricants for TK, whom they owned at the time.
I heard stories of previously dull cu tubing looking like 'a shiny new penny' internally after short period on test.

As a footnote, (W) -TK settled on Solest35 for the aluminum bodied x214/x426/x430 series of recips after a lot of testing. Refrig +A / C application both.

regards
T-P

hendry
14-12-2007, 04:48 PM
AOBB,
your Q is the way to do it right.

1] compatiblity check on refrigerant & gasket materials.
2] drain old oil & charge in new; run few days & send sample for analaysis.
3] repeat step 2 until safe level obtained.
4] reclaim original refrigerant via safe method; vacuum system until -1barG & hold.
5] charge new refrigerant.
6] run & monitor the response.
7] tuning is necessary.

Hope the above answer your Q. write to me directly if you wants more advice/s.