Although they might sound similar, rotary vane air compressors and rotary screw air compressors employ different methods to produce compressed air. Within the casing of a rotary vane compressor, a rotor, usually offset from the center of the casing has vanes or blades which extend outwards to form an airtight seal against the casing. As atmospheric air enters the rotary vane compressor, the rotor spins and the vanes force this air into an increasingly smaller space thus compressing it.
By contrast, a rotary screw compressor uses two tightly interleaved helical screw rotors which, when rotating, pull in atmospheric air. This becomes trapped in the space between the rotors. The rotors are designed so that the space between them progressively decreases. As more air is pulled into the compressor is forced into these increasing tighter spaces between the helical rotors thus compressing it. Both rotary vane and rotary screw air compressors are designed for continuous, long-term running in industrial or manufacturing environments that constantly require high volumes of compressed air provided by technology that produces minimal noise and requires little maintenance.