These high differential pressures are achieved by generally using two stage rotary vane vacuum pump. The pumping action is done in two cylinder-like chambers with rotating shafts on which several vanes "scoop" the vapour and force it through a system of one-way reed valves.
The tolerances between all moving parts are so close that by-passing vapour is minimized. Oil is used in these liquid ring vacuum pump to cool, reduce friction, lubricate and to further reduce vapour by-pass. Different manufacturers recommend specific types of oil with characteristics that optimize the performance of their pump designs.
All high vacuum pumps generally cost over one thousand and sometimes several thousand dollars. Therefore selection of the appropriate pump for the application is critical.
Like an automotive engine, the oil must be kept clean by changing regularly in order to provide optimum performance and reduce expensive repairs. A regular scheduled maintenance program should be introduced that enforces this discipline. Some manufacturers suggest oil changes at least every year.
On-site preventive maintenance consists of flushing the pump of old oil and debris, filling with new oil, changing worn motor belt, and testing the water ring vacuum pumps performance
If your facility does not have a technical service person or group, the best way to ensure this maintenance is achieved is to engage an outside service provider. Pumps may be set up on a scheduled preventive maintenance program where service is performed on site at least once per year or may be delivered to our service shop air conditioning vacuum pump.