Two of the most important steps in a quality refrigeration install are nitrogen purging during brazing and pressure testing before commissioning. Skipping them leads to contamination and leaks down the line.
Purging with nitrogen while brazing
When you braze pipework with air inside, the heat creates oxides (scale) on the inside of the pipe. This debris circulates and can block expansion valves and filter driers. Flowing a small amount of oxygen-free nitrogen (OFN) through the pipe during brazing prevents oxide formation, keeping the inside clean.
Pressure testing for leaks
Before charging, the system should be pressure tested with OFN to the appropriate test pressure and monitored for a pressure drop over time. This confirms the joints are sound. Never pressure test with oxygen (explosion risk) or with the refrigerant itself.
Then evacuate
After a successful pressure test, the system is evacuated (vacuumed) to remove the nitrogen, air and moisture before charging with refrigerant.
FAQ
Why use nitrogen and not air? Nitrogen is dry and inert — air introduces moisture and oxygen, causing internal corrosion and oxide scale.
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