Sampling Techniques: Refrigeration Compressors

Sampling the oil of refrigeration compressors requires care and attention to detail. Compressor fluid is under pressure when the compressor is operating. Sampling should be performed only by HVAC certified technicians.

1. If chiller is operating for at least 30 minutes, Locate a stopcock valve or line fitting between the oil pump and oil filter. Open the valve (Loosen the fitting) and allow at least 2 fl. oz (30 ml or 1/3 of a standard sampling bottle) to flow so as to remove any dead leg debris.
2. Grab a sample of the oil from the flow and fill 7/8 full. Do not fill completely! Place the cap on loosely and allow any excess freon/ammonia to escape. When oil has cooled to room temperature, secure lid tightly.
3. Fill out the label and registration form and place in mailing container and send to laboratory.
4. If chiller is not operating, run auxiliary oil pump for at least 30 minutes before grabbing a sample as directed above.

Note: When oil pump is running, the oil system from the pump to the bearings is positive pressure regardless of type of refrigerant used.

For routine sampling it is suggested to place a ball check-sampling valve between the oil pump and filter. Use a sampling probe for grabbing samples.