Vacuum Pumps Explained Basic working principle HVACRotary vane vacuum pump 12cfm 3/4hp 29hg hvac milker machine hookup+check valve come with a bottle of vacuum oil, just dump it in, you are ready to go! Model VPDS12 Single-stage rotary vane pump 12.0 CFM single phase(110 VAC 60Hz) 3/4 HP motor Continuous Duty VACUUM PUMP, 29.9 inch Hg, Deep Vacuum, With a Built-in isolation Check valve and 2 intake ports!