Centrifugal pump oversizing results in higher initial cost, higher operating costs, and increased maintenance problems over the life of the system when compared to a properly sized pump. It is easy to preach that pumps must not be oversized, in spite of publications and guidance that goes well back in time, pumps are still being specified for much greater head than actually required by the system. Experience in working with a large number of designers has uncovered many factors that lead to pump oversizing. Some of these are pure misunderstanding or failure to adequately analyze the system pumping requirements. These factors can be addressed by training, making sure designers know the elements of pump selection and sizing. Other factors are not so easy to remedy, leaving even experienced, knowledgeable designers with the real possibility that the pumps they specify will be oversized. This paper will detail the reasons that pumps get oversized and offer some suggestions about how to solve the problem.

Units: Dual