ABSTRACT
The problem of the frequency and regularity of complete overhauls of centrifugal pumps is a very controversial one. Most pump designers and specialists consider that a centrifugal pump need not be opened for inspection unless evidence, of either a factual or circumstantial nature, is available to indicate that overhaul is necessary. A schedule should be set up for a fairly frequent complete test of the pumping unit so that the results of this test can be compared with the performance of the pump in its initial condition and so that any sudden falling off in performance can be detected without delay. Circumstantial evidence refers to data accumulated through past experience, either with the pump in question or with similar equipment or similar service. Several criteria are used to determine whether a pump should be subjected to an internal inspection and, possibly, complete overhaul.
