Digital Vacuum Gauge with Case

JB's DV-24N reads vacuum in seven international units: microns, lb/sq-inA, in Hg, mBars, Pascals, Torr, and mTorr. The DV-22 has a micron range of 20 - 9000 micron. It is a good idea to attach the micron gauge to the vacuum pump before evacuation to make sure the pump pulls down to at least 50 micron. If it doesn't, your pump oil is contaminated and should be changed. A compound gauge only indicates that a vacuum is being produced, but does not tell you if moisture and acids are still present in the system. Micron gauges are the only tool to accurately read the low pressure produced when evacuation/dehydration is complete.