References & further reading
- Karassik et al., Pump Handbook — NPSH definitions and field practice.
- ANSI/HI standards for rotodynamic pump tests where applicable to your workflow.
Model assumptions
- Single-line incompressible model; temperature-dependent vapor pressure must be entered consistently with fluid tables.
- NPSHa uses your stated margins and velocity head treatment as implemented in the tool; verify against internal company standards.
- Pump curves, control valve throttling, and transient events are not modeled.
Shareable URL
When the toolbar exposes “Copy shareable link”, inputs can be encoded in the URL so colleagues can reopen the same case. All computations run locally in your browser; this tool may not expose share links yet.
Frequently asked questions
- Why does NPSHa change when I tweak suction line losses?
- Because NPSHa is built from suction-side energy balance including hfs.
- What is the difference between NPSHa and NPSHr, and which does this tool compute?
- NPSHa (available net positive suction head) is set by the suction-side energy balance and is what this tool outputs; NPSHr (required) is a pump characteristic you must read from the manufacturer curve. The selection criterion is NPSHa ≥ NPSHr + safety margin; this tool does not include NPSHr.
- Is head expressed in metres or pressure units, and does it depend on density?
- Hydraulic head is expressed as a fluid-column height (m) and is independent of density; density enters only when converting to pressure (ΔP = ρg·H) or power. This tool computes in SI internally, and you can convert between m, kPa and bar in the unit converter.
Extended copy on this page (headings, references, assumptions, FAQs) may be drafted or localized with AI assistance; engineering judgment and governing codes still apply. Numerical models run locally in your browser as implemented. For contract-critical work, cite primary standards and qualified review.