How to take fridge and air compressor samples

Sampling Guidelines for Refrigeration/Gas Compressors

· For routine sampling it is suggested to place a ball check-sampling valve. Where possible use a sampling probe for grabbing samples.

· Samples should be taken downstream of bearings/oil pump and upstream of filters

· Only draw oil samples from machines that are running at normal operating conditions.  

· Do not draw an oil sample from a machine that is not running or just after start up. If the compressor has recently been turned on allow the compressor to run for at least 20 minutes

· At each compressor allow enough oil to be drained out to ensure the drain valve or sample port is clear of contaminants and also any tubing being used to sample is flushed through to clean the tubing and the sample bottle.

· Once a clean flow has been obtained take the sample of the oil from the flow and fill the sample bottle to ~50%. Do not fill completely! This then allows the bottle to be cleaned with the oil you are sampling.  

· Swill the oil around the bottle and then discard.

· Repeat the sample drawing procedure and fill the bottle to ~80% of the bottle volume.

· Place the cap on loosely and allow any excess refrigerant to escape. When oil has cooled to approximately room temperature, secure the sample bottle lid tightly.  

· On occasions oil drawn from a compressor can contain excess foam – in this instance a larger clean sample bottle should be used which allows the foaming to subside and obtain enough sample of the oil to fill the sample bottle.  

· Refrigeration oils can build up a little pressure and care should be exercised to de-gas the sample bottle before shipping to the lab. This may mean cracking the lid to relieve the built up gas and then securing the lid prior to dispatch.

· Fill out sample label completely including sample date, fluid and machinery hours, serial numbers  

· Send in samples as soon as possible to the lab on the same day they are drawn from the machinery

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