# Reading your result

Source: https://meptools.com/tools/water-pipe-pressure-drop-pump-head/docs/results/

The result panel appears after you press **Calculate** (see
[Getting started](/tools/water-pipe-pressure-drop-pump-head/docs/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.

![Water pipe calculator's worked-example result: headline pump head, regime chip and the KPI row](./_assets/water-pipe-result-panel.png)

## 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](/tools/water-pipe-pressure-drop-pump-head/docs/warnings-and-limits) for what
  each one means.
- **Formulas and references** — the same equation list as
  [Methods & formulas](/tools/water-pipe-pressure-drop-pump-head/docs/methods).
- **Report** — a print preview and the Print / Export PDF buttons; see
  [Saving, sharing & exporting](/tools/water-pipe-pressure-drop-pump-head/docs/exporting-and-saving).

## 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.

![Water pipe calculator with the STALE chip and Recalculate button on the action rail after an input changed](./_assets/water-pipe-stale-recalculate.png)