View Full Version : Best way to identify a refrigerant in a working system?

08-04-2017, 07:28 PM
Hello from NY and thanks for looking at my question. I would like advice on what is the best way to identify what refrigerant is being used in a system. I get called to repair problems at walk-in coolers, most are old, abused, dirty and unlabeled, not even a clue written with magic marker. I take the pressure readings and measure the temperature on the tubes in the center of each coil. I look at the P/T chart and see what comes closest to my readings. Is this ok? I worry about NCGs in the system that are upsetting my P/T comparisons. Is there any other method I can use to confirm the identity of mystery refrigerants? best regards

The Viking
08-04-2017, 09:01 PM
Normally the best way to identify what should be in the system is the expansion valve if one is fitted.
If the system is running OK and keeping temperature, I would look at sub cooling (liquid line pressure/temperature) and super heat (suction line pressure/temperature), assume around 4K on each, look at the P/T charts to see which refrigerant is closest and if they both point towards the same refrigerant that would be my guess.

Another option is to draw some liquid refrigerant out of the system in to a clean cylinder and do the P/T comparison on that.

But it would still only be best guess...
Only true answer comes from a laboratory doing a full analysis.


09-04-2017, 12:54 AM
In your position I would if need be remove the gas and retrofit it depending on what the condensing unit can handle,oil is the issue if you need to top up the system then it's a minefield,but let's say the oil is mineral as badged by the manufacturer then again your limited,over here when I meet old kit it's better to convince the client to scrap the old kit and install new trying to guess what's in there is a fools journey,your clients need to understand that doing detective work costs with no certainty of a solution the long and short of it is change old kit for new? But I may be wrong if they trust your judgement and you can convince them to reinvest hey ho,but clowns who break the rules and do not mark up equipment with labels and documentation do not deserve to be in our industry a box of labels written in ink! cost little.