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 2 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.