@hvacschool: “How can you know when you’ve purged enough?” My son Gavin, who’s a refrigeration tech, asked me that yesterday about a job he’s working on. If my own kid has that question, I figure a lot of other techs do too. At Kalos, we’d had cases where we knew we flowed nitrogen while brazing—and still found copper oxide inside the piping. We were scratching our heads. The missing step was clearing the air before we started heating. Purging clears the air first. Low flow keeps it out while you braze. On a big refrigeration job, that difference can mean far more time and nitrogen than you expect. I put together a tech tip with practical regulator setups, large-pipe and small-pipe outlet details, podcasts and videos, and a calculator for purge time and cylinder use. One pipe volume is a planning estimate, not proof that all the air is gone. Read it and try the calculator: https://www.hvacrschool.com/flowing-nitrogen-purge-first/ —Bryan

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Sunday 06 September 2026 23:26:14 GMT