|Maximum Pressure||20 mpa to 29.4 mpa|
300.sml3",400.sml4",500.sml.5",600,sml.6". Gear pump is the most versatile rotary positive displacement pump & it scores over other types of pd pumps viz. Screw, vane, lobe, tracoidal, radial piston etc. & therefore it is used for the widest range of application i.e. Loading-unloading, transfer, fuel pressurizing, hydraulic, lubrication in ic engines, polymers metering applications etc. Gear pump can develop high pressure uo tp 210 bar in same configuration simply by tightening the working clearances & improving the workmanship, whereas in screw pump the thread length is needed to increase making the pump bulky & difficult to manufacture. In gear pump each tooth gap contributes to the capacity while in screw pump only one pitch length contributes to the capacity thus gear pumps are always cpmpact & efficient. The capacity of the pump varies directly with speed but remain constant against pressure, however some liquid always by-passes to suction due to running clearance between the casing & impeller causing slip which depends upon the differential pressure, viscosity of the liquid & the workmanship. Gear pumps are capable of handling liquids of any viscosity, th slip reduces with increse in viscocity but the frictional power increses. Though the pump has a self priming capability some net positive suction head(npsh) is always required to avoid cavitation, this again depends on the viscosity of the liquid to be pumped & the pumping speed.