How worse is the R 134-A ? 2

[sha3rawy]

is the R 134-a has any cleaning or corrosive effect on the metal of the piping , here is my problem i have an air conditioning unit with carrier compressor it has been modified from R-12 to R-134-A after 100 hrs of operation a sample of oil shows some dirts (oil is black ) no metal content or any theme of metal failure a complete check has been done but no system leaks no metal failure no damage so why the oil turns to black ,some people says that R 134-A has aclean effect on the piping although R-12 has not.

 

[DrRTU]

Was the type of oil changed during the conversion? The system may have been changed from a mineral base to a POE oil. POE is more aggressive than mineral oil on seals and electrical windings. Check if the system was flushed and if the cores were changed. Are the seals/winding compatible with the new oil.

 

[MintJulep]

Have you checked the oil for acid?

 

[sha3rawy]

Yes the type of the oil has been changed, and also the system has been flushed with the recoverd R-12 ( old charge ),but I wonder its the manufacture modification not me or any body else so
why the manufacture didnot inform us with that ? and
Is there any action I can do to adequate my equipment with this modification?.

Thanks for concern I would like to know what is the core refers to ? may be we use another term.

 

[imok2]

General Retrofit Procedure: Centrifugal, Reciprocating AC and Refrigeration Systems

1. If the system is able to run – collect system data and operating conditions prior to retrofit.
2. Isolate the compressor and recover the R-12. Change the lubricant in the compressor to
polyol ester (POE). For hermetic compressors this may require removal of the compressor.
3. Replace any oil in auxilliary components such as oil separators or oil feed systems.
4. Close the system and run with R-12 for 24 hours to circulate the POE and flush the mineral
oil back to the compressor.
5. Repeat steps 1-4 until residual mineral oil level is below 5%. (If the unit is not operational
then perform the oil flushing procedure immediately after startup with R-134a.)
6. Recover the R-12 from the entire system.
7. Perform any maintenance, repair or component replacements, and change filter/driers.
8. Evacuate the system to manufacturer’s specifications.
9. Charge the system with the proper amount of R-134a (usually 85% to 90% of the original
R-12 charge by weight).
10. Operate the system and record new system operation data. Make adjustments to controls
as needed to ensure proper operation.
11. Label the system with the new refrigerant and lubricant type.
Most Common Areas that Require Adjustment or Attention:
• Changing the lubricant to POE
• TXV valve adjustment / superheat setting

 

[sha3rawy]

Thanks imok2
For step (2) I know that for the R-12 refrigerant it has aspecial oil ( mineral oil )to have the designed solubility value and on the other hand the R-134-a has another type of oil not matching with the R-12.also the oil that I am using it now for the 134-a is synthetic polyol ester ( PN EMKARATE RL68H),and the lubricant specification sheet doesnt show it can be used with R-12 or not.

I flush the system with R-12 with the mineral oil and I didnot use the POE eith R-12 during the flushing process so is this the problem .by the way the system has no oil separators so what is the place in the system that may have oil residuals still there ? I think that the compressor is the only place for the oil to accummulate in.

Thanks