Studies on the Durability of Roller Pump (No. 2)

Abstract

An investigation on the durability of a roller pump, particularly the wearing of the pump body and the expansibility of the nylon roller, was conducted. The following are the findings on this study:
(1) The amount of wearing of the outer part of the rotor (HS22) is larger than that of the side wall (Hs34), though both becomes higher with the increase of delivery pressure.
(2) A long run test, using Bordeaux mixture (6-6), at a delivery pressure of 5kg/cm² and 1200 r. p. m., results in a gradual decrease of efficiency for the first 100 hours running time. It has been observed that the decrease in efficiency is more rapid for the next 50 hours running. The fall of efficiency is remarkable in higher pressure.
(3) The influence of the clearance between rotor and side-wall becomes less when the revolution velocity and the delivery pressure is increased.
In a clearance test from 0.1 to 0.3mm, the efficiency is reduced by 10 per cent at least, as the clearance is increased by 0.1mm.
(4) In a comparative test of different roller sizes, one with 17.57mm and another 16.41mm in diameter, both having the same width of rotor ditch at 17.8±0.1mm, total efficiency showed that the larger roller has higher value than the other, especially in higher delivery pressure.
(5) The trouble in operation of the roller pump is often caused by the expansion of the nylon roller.
The roller expands in accordance with the running time, water temperature and the increase of delivery pressure.
The shrinkage of the nylon roller occurs when it is picked out of the water, though it requires longer time than that of expansion under water for the same length of change.