This is of a dry vacuum pump is a pump that does not use any fluids to make a vacuum or contact the process gas and may also discharge to atmosphere. … Timing gears with oil reservoirs and close clearances between the rotors and casing are extra attributes that make up a dried out vacuum pump.
Principle of Operation
Dried out screw vacuum pumps operate with two screw rotors rotating in opposite directions. This traps the moderate to be pumped between your cylinder and the screw chambers and transports it to the gas discharge. … It also results in a lower heat load of the compressed gas.