Read pressure breakdown, NPSH margin, and sensitivity to vapor pressure or suction loss to find risky operating conditions.
Parameters
Suction absolute pressure
kPa
Absolute pressure at pump or valve inlet.
Vapor pressure
kPa
Saturation vapor pressure at liquid temperature.
Suction loss
m
Head loss in suction piping and fittings.
Required NPSH
m
Equipment NPSHr.
Results
—
NPSHa
—
NPSH margin
—
NPSH ratio
—
Risk index
NPSH breakdown
Cavitation risk
Loss sensitivity curve
Model and equations
$$NPSH_a=\frac{p_s-p_v}{\rho g}+z-h_f$$
NPSHa expresses the available head before liquid vaporizes at pump suction. Vapor pressure strongly depends on temperature, so warm liquids or high elevation can quickly consume margin.
How to read it
The breakdown view subtracts vapor pressure and suction loss from suction pressure.
The risk view highlights conditions below required NPSH.
The curve view shows how loss or vapor pressure consumes margin.
Learn Cavitation Npsh Margin Detail by dialogue
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When reading Cavitation Npsh Margin Detail, where should I look first? Moving Suction absolute pressure changes both the plots and the result cards.
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Start with NPSHa, but do not treat the number as the whole answer. Use NPSH breakdown to confirm the assumed state, then read Cavitation risk for the distribution or trend. The breakdown view subtracts vapor pressure and suction loss from suction pressure.
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I can see why Suction absolute pressure changes NPSHa. How should I judge the influence of Vapor pressure?
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Move Vapor pressure in small steps and watch NPSH margin. That reveals which term is controlling the result. NPSHa expresses the available head before liquid vaporizes at pump suction. Vapor pressure strongly depends on temperature, so warm liquids or high elevation can quickly consume margin. A single operating point is not enough; sweep the realistic scatter range.
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What is Loss sensitivity curve for? It feels like the ordinary curve already tells the story.
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Loss sensitivity curve is for finding boundaries where the condition becomes risky or margin collapses quickly. The risk view highlights conditions below required NPSH. In Suction-condition checks during pump selection, the important question is often what happens after a small change, not only the nominal value.
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So if NPSHa is within the target, can I accept the condition?
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Treat this as a first-pass review. It helps with Assessing piping-loss changes after layout revisions and Reviewing cavitation margin at elevated liquid temperature, but final decisions still need standards, measured data, detailed analysis, and vendor limits. The curve view shows how loss or vapor pressure consumes margin.
Practical use
Suction-condition checks during pump selection.
Assessing piping-loss changes after layout revisions.
Reviewing cavitation margin at elevated liquid temperature.
FAQ
Start with NPSHa and NPSH margin. Then use NPSH breakdown to confirm the assumed state and Cavitation risk to read distribution or bias. The breakdown view subtracts vapor pressure and suction loss from suction pressure
Move Suction absolute pressure alone, then move Vapor pressure by a comparable amount and compare the change in NPSHa. Loss sensitivity curve shows combinations where margin or performance changes quickly.
Use it for Suction-condition checks during pump selection. Instead of trusting a single point, widen the input range and check whether NPSHa keeps enough margin before moving to detailed analysis.
NPSHa expresses the available head before liquid vaporizes at pump suction. Vapor pressure strongly depends on temperature, so warm liquids or high elevation can quickly consume margin. Final decisions still require standards, measured data, detailed analysis, and vendor limits.