Rotary Screw
In a rotary screw rotor compressor the air is trapped and sealed with oil between the male and female rotor profiles. As the rotors rotate and mesh the air is pushed along the rotors into a smaller and smaller space. The pressure will increase to allow the given volume of air to fit into the cavities in the compression chamber.
Industrial Air Power carries rotary screw air compressors from 5 to 50 HP.