The work principle and advantages and disadvantages of variable displacement pump (2)

（ ） Reciprocating pumps, rotary vane vacuum pumps, vacuum pumps, roots pump is reciprocating or by gas drainage, compression and discharge rotary piston. Their advantage is that, in using the new vacuum pump is relatively high, but the piston moving parts, so the wear of piston is inevitable, because in the increase of the maintenance work will continue to decline, until the vacuum production cannot meet the requirements. This kind of pump noise, fuel consumption, high failure rate is the fatal flaws, usually need to open the spare one, this virtually increases the equipment investment and operation cost. In addition, if such a water vapour and other gases pumped coagulation, lubricating oil so only applies to the condensate pump ( Air type) Gas, it cannot use particle medium pump, to limit its scope.
( ） By the water ring vacuum pump is installed in the pump shell is more eccentric rotor blade rotation, throw the pump shell and the pump shell, form the concentric circles, hydrosphere and rotor blade, form a volume cycle, the gas suction, compression and emissions. Its low vacuum suction capacity, water and steam is condensed gas. The disadvantage is that the vacuum is low; Can't pump with granular media; The rotor high-speed rotation is not easy to do the anti-corrosion treatment, it is not pumping corrosive medium.