Reading your result — MEP Tools
What the headline number, the KPI row and each evidence card in the result panel mean.
The result panel appears after you press Calculate (see Getting started for how the Calculate / Recalculate / STALE cycle works). This page explains what each part of it means.
The headline
- Total pump head, in metres, is the hero number.
- Next to it, a status chip names the flow regime: Laminar, Transitional, Turbulent, or No flow. This tool makes no pass/fail judgement — it has no code limit or sizing table — so Transitional is the only regime flagged as a caution; the rest are neutral.
- Two sub-lines echo the total as an equivalent pressure (kPa, at the density you entered) and the Reynolds number, flow, diameter and length used for the run.
The KPI row
| KPI | Unit | Notes |
|---|---|---|
| Velocity | m/s | |
| Pipe + fitting Δp | kPa | Straight-pipe friction drop plus fitting/valve minor loss. |
| Hydraulic power | kW | P_hyd = ρ g Q H. |
| Shaft power | kW | Shown as — when Pump efficiency is left blank. |
Where the head goes
A composition card breaks the total head into its four components — pipe friction, fittings and valves, static lift (or gravity assist when your static head is negative), and required residual pressure — and adds one line naming whichever term is the largest contributor, for example "Pipe friction is the dominant term — a larger bore or a shorter route is the only lever." Two special cases override that: a total head at or below zero reads "no pump head is required for this arrangement," and zero flow reads "there are no friction or fitting losses — the head is static lift and residual pressure only." A transitional-flow caveat is appended to either message when the regime is Transitional.
Evidence cards
Below the headline, expandable cards give the full working:
- Head breakdown — a table of friction / fittings / static / residual / total, each with its head (m), pressure (kPa) and share of the gross demand.
- Fittings and valves — every row from your fitting schedule with its K, head and pressure contribution, plus your source note (or a "no source cited" flag).
- Calculation steps — all 14 steps from pipe area through shaft power, each shown symbolically, then substituted with your numbers, then as a result, linked to its formula reference.
- Assumptions and warnings — see Warnings & limits for what each one means.
- Formulas and references — the same equation list as Methods & formulas.
- Report — a print preview and the Print / Export PDF buttons; see Saving, sharing & exporting.
Editing after a run
Change any input once a result is showing and the result is marked STALE — it still shows the previous run's numbers until you press Recalculate, so the panel never silently blends a result with edits it hasn't accounted for yet.
