Abstract
A 2 1/2 in. model pump was tested on an unbleached sulphite stock. The test setup was incorporated with a screw feeder of disc-refiner so that a thick stock can be forced into the pump. The pump was run at oven-dry consistencies ranging from 3.08 percent to 10.48 percent at high discharge pressure.Beyond this consistency, the motor of screw feeder would be overloaded. Therefore, satisfactory operation in this test was limited to 10 percent consistency. At the high speed of the test, it was observed that volumetric and overall efficiency increased consistency of stock. And these increased values may explain the higher resistance to internal leakage. Comparing the curves for 220 r.p.m. and 550 r.p.m. for which the fiberizing consistency was the same, the higher speed gave lower internal leakage.For the same reason, it may explain that the efficiency increases with consistency of stock at a given speed.
The advantages of this pump over reciprocating pumps are quiet operation and absence of excessive stress in the pipe line owing to the uniform discharge, and the advantages over centrifugal pumps are its flexibility in regard to capacity, positive displacement, high pumping head and its nearly uniform efficiency under a wide range of conditions.
