Buyer guide
Water Pump Total Head vs Flow Rate: A Practical Buyer Guide
Catalogues quote a maximum head and a maximum flow for each pump. Buyers add them together in their heads — “28 metres and 60 cubic metres an hour” — and then find the delivered flow is far below what they expected once the pipe run and lift are real.
The short answer
- The two figures describe the ends of one curve, not two abilities. Flow falls as head rises; at maximum head the flow is effectively zero.
- Specify a duty point — a flow at a head — not a pump model. The duty point is what the job needs, and it is what a supplier should quote against.
- Total head is lift plus friction plus outlet pressure. Most underestimated part is friction, which grows with hose length and falls sharply with larger hose diameter.
- If the duty point sits near the right-hand end of the curve, the next size up is normally the cheaper decision over a season.
Catalogue endpoints for the four pump sizes
Read from the catalogue row for each model. Scroll the table sideways on a phone.
| Model | Connections | Maximum flow | Maximum head | Suction lift | Net weight |
|---|---|---|---|---|---|
| FSHWP20 | 50*50, 2*2 | 36 m³/h | 46 m | 8 m | 26 kg |
| FSHWP30 | 80*80, 3*3 | 60 m³/h | 32 m | 8 m | 28 kg |
| FSHWP40 | 100*100, 4*4 | 80 m³/h | 28 m | 8 m | 32 kg |
| FSHWP60 | 150*150, 6*6 | 160 m³/h | 26 m | 8 m | 90 kg |
These are the catalogue endpoints. Fujiheng publishes the operating curve for a model on request rather than restating an intermediate point here, because a real curve cannot be reconstructed from two endpoints.
How to choose
Calculate the static lift
Height from the water surface to the outlet, in metres. Use the lowest water level you expect, not the average — a falling water table is what strands a pump.
Calculate the friction head
Length of pipe, number of bends, valves and the hose diameter. Halving the diameter multiplies friction many times over; this is where most installations lose their performance.
Add the outlet pressure you need
If the water goes into a pressurised line, a sprinkler or a tank at height, that requirement is part of the total head.
Turn the total into a duty point
You now have a required flow at a required head. Give both numbers to the supplier and ask which model meets that point with margin, and for the curve to show it.
Check the suction side separately
The suction lift maximum is measured under good conditions. A long suction hose, a dirty strainer or a high installation all reduce it, and cavitation shows up as noise and reduced flow.
Suited to
- Any installation where the run is long, the lift is significant, or the flow matters.
- Comparing two pump sizes before buying.
Not the right choice when
- Reading maximum head and maximum flow as simultaneous capabilities.
- Sizing on the outlet connection size alone.
How this is checked before it ships
Why the endpoints are published and the curve is quoted
A catalogue row gives one head and one flow per model. Publishing an intermediate figure without the test data behind it would be a guess, so the curve is supplied for the specific model on request.
Per-model packing and loading
Container quantities are stated per model so a mixed order can be planned: 330 units per 20 ft for the 2 and 3 inch sets, 120 for the 6 inch set.
More on the production sequence and the documents issued with an order: certifications, testing and quality control.
Models and pages referred to in this guide
About this guide
- Prepared by
- Fujiheng technical sales team
- How the figures were checked
- Figures cross-checked against the printed catalogue row for each model. Third-party engine figures are taken from the maker’s published data and labelled in the text.
- Last reviewed
- 2026-10-20
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Contact
Tell us what you need
Send us your market, required output and configuration and we will come back with a suitable model and quotation. We reply to enquiries within one working day.
- Telephone
- 0086-18662020695
- Factory and office
- Yancheng Fujiheng Power Machinery Co., Ltd.
Teyong Industrial Park, Sheyang County, Yancheng, Jiangsu, China
Teyong Industrial Park, Sheyang County, Yancheng, Jiangsu, China
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