Dry vacuum pump
The definition of a dry vacuum pump is a pump that does not use any fluids to create a vacuum or contact the process gas and can also discharge to atmosphere. ... Timing gears with oil reservoirs and close clearances between the rotors and housing are additional attributes that make up a dry vacuum pump.
Principle of Operation
Dry screw vacuum pumps operate with two screw rotors rotating in opposite directions. This traps the medium to be pumped between the cylinder and the screw chambers and transports it to the gas discharge. ... It also results in a lower heat load of the compressed gas.