A screw air compressor is a type of gas compressor, such as an air compressor, that uses a rotary-type positive-displacement mechanism. These compressors are common in industrial applications and replace more traditional piston compressors where larger volumes of compressed gas are needed, e.g. for large refrigeration cycles such as chillers, or for compressed air systems to operate food processing or packaging equipment. For smaller rotor sizes the inherent leakage in the rotors becomes much more significant, leading to this type of mechanism being less suitable for smaller compressors than piston compressors.