Question
Download Solution PDFNet positive suction head (NPSH), which plays an important role in the proper selection of pumps is given by ________.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
The Net Positive Suction Head (NPSH) is defined as the absolute pressure head at the inlet to the pump, minus the vapour pressure head (in absolute units) plus the velocity head.
\({\rm{NPSH}} = \frac{{{P_1}}}{{\rho g}} - \frac{{{P_v}}}{{\rho g}} + \frac{{{v_s}^2}}{{2g}}\)
Where,
P1: Absolute pressure at the inlet of the pump
Pv: Vapour pressure at the inlet
vs= velocity of the fluid in the suction pipe
As the pump speed increases, vs will also increase. But NPSH may increase or decrease because it depends upon other factors also
Effect of Vapor Pressure on NPSH
- Vapor pressure is the amount of pressure required for a specific liquid to stay in liquid form.
- As the temperature of the liquid increases, the vapor pressure increases, decreasing the amount of NPSHA.
- If consideration is not taken into the fluid temperature and vapor pressure met, the liquid could flash to a gas state near the pump suction.
Last updated on May 28, 2025
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