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Start Flowing Nitrogen Sooner
My technician (and brother-in-law), Bert, made a good point. (It's hard for me to admit it, but it's true.) When he needs to open the refrigerant circuit to make a repair, regardless of whether he is recovering or pumping down, he pulls out his nitrogen tank and his regulator. (We like the Western Enterprises VN-500 shown above. You can get it at TruTechTools.com and get a discount when you use the code GETSCHOOLED at checkout.)
How Bert flows nitrogen while brazing
Once the refrigerant has been fully pumped down or recovered, instead of opening the system to the atmosphere and exposing it to air and moisture, he simply puts it in “BRZ” mode. That's brazing mode; he introduces a very low flow of nitrogen, only 2-5 standard cubic feet per hour (SCFH). Now, when he cuts into the system to replace a line drier, a coil, a compressor, or an accumulator (you get the idea), the system will stay dry. It will also be less likely that anything undesirable enters the system. You simply connect the regulator to your center hose and direct the flow to the high side, low side, or both, depending on what part of the system you have open.
Once the system is all dry and has been fit into place, you're ready to flow nitrogen while brazing, do a nitrogen pressure test, and even triple evacuate if nitrogen is needed for that.
What prevents techs from flowing nitrogen while brazing?
The biggest hurdle to getting techs to flow nitrogen while brazing is getting the nitrogen tank off the truck. If you get in the habit of connecting nitrogen before you ever cut or open the lines, it even further reduces the chance that you “forget.” It also increases the chances that your system is clean and dry.
Just a thought (from Bert).
If you want to watch a video of Bert explaining how to flow nitrogen while brazing, you can head on over to our YouTube channel and watch him do his thing HERE. We've also written another article that explains WHY we flow nitrogen while brazing, which you can read HERE.
This is the way I taught to braze in 1983. are you saying there technicians out there that don’t use nitrogen whenever the system is about to be opened?
Always used nitrogen prior to the everyday use of a micron gauge in the 80’s & 90’s. It never failed me.