The air vacuum pump is a venturi-type AC pump that eliminates moisture from air-con systems, which makes it safe and easy to add refrigerant. The air flow vacuum pump is easy to operate and pulls complete vacuum within two mins of being linked to an air line. Includes 1/2 in. ACME (R134a) and R12 connectors.
Air-driven vacuum pumps work when compressed air passing through an orifice increases its velocity and lowers its air 
pressure. Ambient surroundings is used through stations in the generator, creating suction and vacuum. The air flow stream exits through the exhaust. … These functions require vacuum pumps.