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