Popular Pumps & Systems columnist Jim Elsey is a mechanical engineer with five decades of design and operating experience, primarily focused on rotating equipment reliability in most all industrial applications and markets around the world. Elsey is an active member of the American Society of Mechanical Engineers, the American Society of Metals, the National Association of Corrosion Engineers and the Naval Submarine League. He is the principal of MaDDog Pump Consultants LLC. He may be reached at jim.elsey@spiohio.com.

The impeller and casing must be matched to each other or the results will be a disaster.
Inspired by recent events, I hope to clear up the continual confusion around net positive suction head (NPSH), specifically as it pertains to self-priming pumps on a lift application.