Minimaler Einlassdruck (Net Positive Inlet Pressure)

Net positive inlet pressure is the absolute pressure required at the inlet of the pump to prevent cavitation. Similar to net positive suction head (NPSH).

Net positive inlet pressure can be noted with the suffix “A” (NPIPa) for available NPIP from the system or "R" (NPIPr) for NPIP required by the pump. Similar to Net Positive Suction Head (NPSH).

Pump cavitation occurs when the pressure at the pump inlet drops below the vapor pressure of the liquid. Vapor bubbles form at the inlet of the pump and are moved to the outlet where they collapse, often taking small pieces of the pump with them.

Cavitation is often characterized by:

1. Loud noise often described as a grinding or “marbles” in the pump
2. Loss of capacity (bubbles are now taking up space where liquid should be)
3. Pitting damage to parts as material is removed by the collapsing bubbles

To learn more, watch this video about cavitation.