Back in the days of new construction when we would install a new system in a house, furnace,a/c, duct work, and gas pipe. I would charge the gas pipe with 20#'s of air for the pressure test. And let it set overnight for the inspector to see it was air tight. If it was a 70 degree day when I filled it with air then the outdoor temperature dropped to 45 degree's. When the mech inspector checked the pressure gauge it would be at about 17#'s, not 20#'s. The temperature affected the final reading. Will the same thing happen when using nitrogen?
I filled a lineset with 150# of nitrogen after fixing a couple leaks I found. Last service call of a very long 12 hour day. I'm going back tomorrow after 4 days because the customer was leaving town that night. There is going to be a 35degree temperature difference from the time I put the nitrogen in the lineset. Will there be a different affect with the nitrogen because of no moisture in nitrogen? Does temperature make nitrogen expand and contract like CO2 ?