What does NPSH stand for?

• A. What does NPSH stand for?
• B. Net Positive Suction Head Available
• C. Net Pressure Suction Head Available
• D. Net Positive Suction Head Required

Answer: (B)

Net Positive Suction Head Available is the energy on the suction side of the pump that can be converted to pressure to keep the liquid from cavitating at the impeller. Cavitation occurs when suction pressure falls near or below the liquid’s vapor pressure, so having enough NPSH_available helps prevent that. It is determined by the system upstream of the pump (tank height, piping pressure, velocity heads, and friction losses) and is then compared to the pump’s required head to avoid cavitation (NPSH_required). That relationship—available versus required—keeps the pump operating safely at the chosen flow. The other phrases aren’t the standard term for what NPSH stands for.