Professional-use disclosure

1. Screening outputs, not approvals

Calculator results, reference values, guides, and Workspace reports are provided for informational screening. They are not detailed engineering, not a code compliance determination, not a custody measurement, not a vendor quotation, and not a promise of savings or performance. Do not size safety devices, set relief setpoints, or approve purchases from a screening number alone.

2. Governing requirements always win

Where this site discusses sizing or selection practice, the applicable codes and standards (e.g. IEC 60534 for control valves, ISO 5167 for differential-pressure metering), the authority having jurisdiction, and the equipment manufacturer's instructions govern. If a calculator result and a governing requirement disagree, the requirement wins — file the discrepancy, do not average it.

3. Fluid data and datasheets must be verified

• Confirm the fluid datasheet at flowing temperature: density, viscosity, and vapor pressure. The tools never look these up; wrong properties in means wrong answers out.
• Confirm the measured duty at the operating point: flow, suction and discharge pressures, static heads, and levels — plus one known duty to calibrate any system curve.
• Confirm equipment facts from primary sources: rated Cv(h) tables or rangeability R, pump curves with NPSHr at the operating flow (not just BEP), meter calibration factor C with beta and straight-run compliance, and vessel strapping tables including heads.

4. Known model limits, stated plainly

• Valve opening estimates without datasheet curve data are blocked by design; the estimator shows a gate warning and refuses to compute.
• Friction screening uses Blasius for smooth turbulent flow; rough pipe or Re beyond 1e5 needs Colebrook/Moody before detailed design.
• Gas-valve numbers are screening with a choked-flow flag at P2/P1 ≤ 0.5; full sizing follows IEC 60534.
• NPSH screening demands ≥ 1 m margin; anything under 0.5 m is a stop-work condition, not a judgment call.
• Orifice and totalizer tools screen operations; money measurement follows full ISO 5167 with calibrated hardware.
• Steady-state only: no water hammer, startup surge, or loop-dynamics analysis anywhere on this site.

5. No conflicts, no paid placement

Calculator defaults and guide examples are editorial choices, not endorsements. The site does not accept payment to favor equipment, vendors, or rate plans in its tools or content. If that ever changes for a specific page, the relationship will be stated on that page, adjacent to the affected numbers.

6. Corrections

If a page contains an unclear definition, a broken result, a stale reference, or missing source context, send the URL and the specific issue through Contact the site. Verified corrections are fixed in the source catalog, re-tested through the engine suite, re-synced, and noted on the page with a revision date.