Nitrogen purging is the process of flowing dry nitrogen through copper refrigerant lines while they are being Brazed. This step is critical because it prevents "oxidation" (soot and scale) from forming inside the pipe, which could later clog the Expansion Valve. Without nitrogen, the internal scale will eventually travel into the Compressor and cause permanent damage. This is a mandatory step for any professional ACIq or MrCool installation involving a line set. You can find nitrogen regulators and tank accessories in our Parts department for technicians. Purging ensures that the inside of your pipes remains as clean and shiny as the day they were made. It is a hallmark of a high-quality "best practices" installation that many cut-rate installers skip. Taking the time to nitrogen purge is the best way to protect your system's long-term efficiency and warranty.