MICROFICHE REFERENCE LIBFUUW - Cd3wd.com

87auger pumps can be produced by light industry in developing countries.In Thailand, such a device, called a “Debbharid,” is produced by some 25factories at the rate of 47,000 per year (Kishida, 1971).3.3.3 RotorAnother subclass of rotary water lifters are those which employ ahigh speed rotor within a fixed casing (or stator) and are commonly calledrotary pumps. A wide variety of rotor designs and combinations have beendeveloped. All rotary pumps operate in basically the same manner--therotor (or rotors) traps water between itself and the stator and then pushesit from the inlet to a higher head outlet. An interesting feature of rotarypumps is that they can pump in either direction, i.e., the suction ordischarge line can be attached to either orifice, if, of course, the driveris connected appropriately. Although the discharge is separated intoindividual massess by the appendages of the rotor(s), the high speedoperation of these pumps (normally 40-3600 rpm) presents an almostcontinuous flow of water. Like reciprocating pumps, rotary pumps maintainan almost constant Q for varying H , and because pressure is usuallythe major concern in their application, pressure (e.g., psi), rather thanQ , is often the common abscissa.Because rotary pumps must trap the water with relatively no leakagein order to be efficient, only very small clearances (0.001-0.002 in.)must be allowed between rotor and stator. Therefore, with only twoexceptions, rotary pumps cannot handle abrasive fluids without excessivewear. They have been found to be used most advantageously in pumping highviscosity fluids at low Q and high H --however, they are not limitedto those applications.Rotary pumps have been developed to handle upwards