Rotary vane combination compressor and vacuum pumps generate air pressure or vacuum in the same unit. Two ports are available to connect a hose, one for pressure and one for vacuum. Rotary vane units create continuous pressure or vacuum that is higher in air volume than diaphragm or piston combination pumps. They continuously draw air into the air chamber where rotating vanes generate air pressure or vacuum. These combination units are used for continuous-duty low-pressure and low-vacuum applications. They are often used for quiet operation applications in medical and dental offices, or for pond aeration.