Hvac School - For Techs, By Techs

In this short podcast, Bryan talks about where to place the micron gauge during evacuation and how to think about micron gauge positioning. Evacuation (deep vacuum) doesn't remove solid contaminants, and vaporizing liquid water is a time-consuming process; its main purpose is to remove water vapor, air, and nitrogen gases from the HVAC/R system. When you pull down below 500 microns and hold that pressure, we can make sure we have a clean, dry, and tight (leak-free) system. As we started using R-410A and POE oil, water in the system became a much bigger issue than it was with mineral oil (it was never to have water in the system, but it breaks down POE oil). Before we start pulling a vacuum on the system, we need to attach our micron gauge to the pump while it's isolated to make sure the pump is working. A modern vacuum pump should pull down below 100 microns in 30-60 seconds; if your pump can't pull down to 100 microns in under a minute when isolated, then you'll want to change the oil (possibly multiple time