The air vacuum pump is a venturi-type AC pump that eliminates moisture from air-con systems, making it safe and easy to add refrigerant. The air flow vacuum pump is easy to operate and pulls full vacuum within two mins of being connected to an air range. Contains 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 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.