Issue:
Mineral Oil Contamination Cleanup
Resolution:
Hudson Technologies is the best way to handle mineral oil contamination, but if they are not available the following procedure will work.
The mineral oil when used in R134a is not miscible. The mineral oil will turn to a thick wax-like substance that floats on the liquid in the evaporator and coats the tubes with a layer of wax. You will need to use a solvent to dissolve the mineral oil.
Use R22 as the solvent. Connect a drum of the R22 to the bottom of the chiller, and fill the shells with liquid R22 using a transfer pump. Vent the vapor back to the drum. Then drain the refrigerant (contaminated with mineral oil) from the shells. This flushing procedure will dissolve the wax and allowing it to be removed from the shells. Then run the contaminated R22 through a distilling process to separate out the mineral oil.
You will need to do this for both shells, and you will need to somehow flush the interconnecting lines and internal surfaces of the compressor as well. To accomplish this could take a large amount of liquid, perhaps 3 times the normal system charge. If you have isolation valves that will help.
As an alternate, if you can get your hands on some R12, it will work equally good in dissolving the oil. You could even run the RTHC/RTAC for a couple hours to flush the I/C pipes and the compressor. A second alternative would be to charge the chiller with R22 and run it for a couple of hours, while being careful to keep condensing pressure below 200 psig. Both of these approaches would reduce the amount of R22 required to flush the system and would be more effective in getting the mineral oil out.
You will probably need to do this at least twice. Our experience has been that the residual of mineral oil left in the system must drop to 1%, or less. So a chemical sample should be taken of the R22 that has been withdrawn to see how contaminated with mineral oil it is after each flushing procedure.
Notes:
Changes:
Other Question/Problem/Cause Statements:
- Mineral Oil Contamination Cleanup
Facts:
- RTAC
- RTHD
Document Identifier: DOC-77178
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.