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Pressione di ingresso netta positiva
La pressione assoluta richiesta all'ingresso della pompa per evitare la cavitazione, indicata con il suffisso “A” per disponibile dal sistema o “R” per richiesta dalla pompa. Simile all'NPSH.
What is net positive inlet pressure (NPIP)?
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).
What is cavitation?
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:
- Loud noise often described as a grinding or “marbles” in the pump
- Loss of capacity (bubbles are now taking up space where liquid should be)
- Pitting damage to parts as material is removed by the collapsing bubbles
To learn more, watch this video about cavitation.