The air vacuum pump is a venturi-type AC pump that eliminates moisture from air conditioning systems, which makes it safe and easy to add refrigerant. The air flow vacuum pump is easy to run and pulls full vacuum within two minutes of being connected to an air collection. Contains 1/2 in. ACME (R134a) and R12 connectors.
Air-driven vacuum pumps work when compressed air passing via an orifice increases its velocity and lowers its 
air pressure. Ambient air flow is drawn in through channels in the generator, creating suction and vacuum. The atmosphere stream exits through the exhaust. … These operations require vacuum pumps.