HVAC 156 Nitrogen test with trace gas

Part 4 Nitrogen pressure test with Trace gas

We add a trace (small amount) of refrigerant to the system and then pressure test with nitrogen. The trace gases allows an electronic "sniffer" type leak detector to pick up a refrigerant leak while the nitrogen provides the pressure needed to push it out.

We also discuss using the equipment data tag's lowest pressure test point for pressure testing.
1 techs over pressure equipment and cause leaks
2 techs can damage metering devices, pressure switches, pressure transducers or Electronic expansion valves.
3 The electrical connection in the compressor (Copland fusite) is not designed to handled high pressure and can be damaged
4 Its possible for the nitrogen pressure to push under the suction valve and mix nitrogen with the refrigerant causing refrigerant contamination

The Nitrogen trace gas method has some drawbacks
A: The temperature pressure compensation will not work with a mixed gas
B: in some cases the nitrogen and the refrigerant does not mix and the nitrogen can leak out without the refrigerant and the detector is unable to sense the leak.

This method is beneficial if a tech already has a "sniffer" style leak detector and does not have digital gauges.

Its about knowing multiple methods and applying the one that best fits the needs for the circumstance.