Keperluan Nitrogen Semasa Brazing

Is nitrogen a must while brazing AC lines?

 I have an R410A unit and I've read that an inert gas must be used to sweep the lines while brazing due to the r410a's ability to move the oxidation through the system than compared to an R22. Most people prefer nitrogen from what I've been reading, but it is becoming too hard or too expensive for me to get it.
I do have an air compressor and the air seems pretty dry. I have a filter from the factory on the liquid line of the condensor and I'm installing a moisture indicator as well.
I've heard that some still don't purge the lines if using a filter, bad idea? I can't imagine the oxidation to be that large and the filter would likely trap it and not clog the filter.
Thanks for the help!

 

failing to purge a 410a system with nitrogen before/during brazing wont necessarily cause a problem but increases the chance of a problem..the filter/drier in the liquid line will catch the "flakes" that form on the inside of the pipe and circulate through the system but even if you locate the drier near the indoor coil,you still have the solder joint at the outlet of the drier who's flakes wont be captured by the drier screen because they are downsteam of the body of the drier...those flakes could clog the strainer inside the txv,or otherwise affect the txv...i dont know why 410a systems are more prone to problems from failing to purge while brazing but i've been told that either the refrigerant itself or the "poe"oil in the compressor has a greater attraction to moisture than r-22 systems and their type oil..therfore doing everything by the book is more important on a 410a system,such as installing a large liquid drier [thats rated for puron],,purging with nitrogen while brazing,and evacuating system thoroughly before charging.......the flakes produced while brazing without nitrogen are caused by the presence of oxygen,not moisture.. nitrogen is basically air without the oxygen and moisture...it doesnt require very much nitrogen to purge the system,,just need to have a LITTLE pressure going in while leaving the other port open so it can flow without building any pressure that could cause solder joint leak from nitrogen exiting systen through the solder joint while brazing.....also be sure to take pressure and temperature readings while charging,,and charge per mfr recommendations....usually 10-12 deg "subcooling" is required...dont just add puron until the line gets cold........dan

 

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