System effects in positive displacement pumping

摘要

In the September 1998 issue of World Pumps, Stan Shiels discussed the system effects on rotodynamic pump performance and efficiency. This month, Brian Nesbitt looks at how positive displacement pumps react to systems and clarifies the importantdifferences. In two respects PD pumps behave exactly the same as rotodynamic pumps. Firstly, the pump can only operate at the intersection of the pump and system characteristics. Secondly, overestimating the discharge pressure or adding safety marginsreduces operating efficiency.