Turbomachinery Laboratory, Texas A&M Engineering Experiment Station
Abstract
Case StudiesIt is well understood that static pressure at the inlet of reciprocating pumps, quantified typically by Net Positive Suction
Head Available (NPSHA), must be sufficient to avoid cavitation in the pump suction manifold and chamber. In an effort to
conserve NPSHA, pump designers generally rely on rules of thumb that resist the addition of pressure drop elements such
as restrictive orifice plates, choke tubes and line-size reductions to the inlet piping of all pumps, including reciprocating
pumps.
Another design consideration of reciprocating pumps is the generation of pressure pulsations due to pump piston and valve
motion. Uncontrolled pulsations can result in cavitation and vibration-related fatigue failures. In many cases, pressure drop
elements are required to control pressure pulsations. Can there be a balance between the pulsation control benefits of
pressure drop elements and the need to meet NPSHA?
This paper is of interest to designers and engineers working with reciprocating pump installations. It aims at challenging
industry resistance to using pressure drop elements in the suction piping of reciprocating pumps by, first, outlining the
virtues achieved in terms of pulsation and vibration control, and second, presenting results from numerical simulations
(one-dimensional pulsation and detailed CFD modelling). Recent field data from a quintuplex pump installation were used
to validate the 1-D pulsation model. The results show that well-designed orifice plates, and other pressure drop elements,
are beneficial for reducing pulsations and cavitation risks; and can be used in the suction piping of reciprocating pumps
