What does NPSH stand for?

• A. Net Positive Suction Head
• B. Net Positive Supply Head
• C. Negative Pressure Suction Head
• D. Net Pressure Suction Head

Answer: (A)

Net Positive Suction Head describes the pressure energy available on the pump’s suction side to keep the liquid from flashing into vapor and cavitating. In practical terms, it’s the height of liquid column (head) that can be sustained at the suction before vaporization begins. This term is used as Net Positive Suction Head, with two related concepts: the available head (NPSHa) and the required head (NPSHr) the pump needs to avoid cavitation. The correct choice uses the established name that reflects suction-side pressure energy and positive head to prevent cavitation.

The other options aren’t standard terms for this concept. Net Positive Supply Head would imply a supply-side term not used in this context, Negative Pressure Suction Head would misrepresent the positive head needed to prevent cavitation, and Net Pressure Suction Head substitutes “Pressure” for the conventional “Suction” phrasing, which isn’t the accepted terminology.