This rotor is equipped with grooves in which the vanes are inserted. Because of the centrifugal force, during the rotation the vanes are pushed into contact with the body, creating close spaces that increase their volume drawing air from the container to be emptied and expelling it from the “outlet duct”. Oil-free rotary vane pumps can run continuously both at atmospheric pressure and at the highest vacuum. However, they cannot be used when the aspirated air contains moisture, oil or other traces of liquid.
All versions can be used as compressors.
These pumps may run continuously within certain pressure ranges, or connected to containers to be emptied, whose volume is appropriately sized for the pump flow rate. Long-term use at atmospheric pressure is not recommended.
The lubrification allows this pumps to intake water vapour. To avoid a condensation of the water vapour, the lubricated rotary vane vacuum pumps are equipped with the gas ballast, a system that introduces air in the compression stage and changes the vapour saturation pressure thus avoiding the condensation. Into the WR pump version the gas ballast system is improved and reinforced.
Moreover, the shaft sealing is ensured by a dynamic gasket preventing any leakage.
These lobe pumps should always be used together with a primary lubricated rotary vane vacuum pump increasing the total flow rate at low operating pressures and reaching a great improvement of the final pressure.
Small vortexes of air created by the centrifugal force and the rotation are dragged by the vanes from the aspiration toward the drain. There are no parts in contact, thus the blowers do not require routine maintenance but, since the intake air is also used as cooling fluid, they can operate continuously only within certain ranges of pressure. To prevent a damage of the engine it is indeed necessary to install vacuum and pressure limiting valves.
All versions can be used as compressors. If used as a compressor, the output flow is clean and free of pulsations.