EngiMetric Arena / Design Challenge
What total dynamic head must the pump produce?
Competency Design and sizing primary Quantitative reasoning supporting Systems and balances supporting
What you should take away: Assemble total dynamic head from its four components, including converting residual pressure to head.
The situation
What is happening
A pump lifts water 18 m, overcomes 7.5 m of pipe friction and 2.1 m of minor losses, and must leave the discharge at 1.5 bar gauge. What total dynamic head must the pump produce?
Given
| Quantity | Value | Unit | Note |
|---|---|---|---|
| Static lift | 18 | m | Elevation difference. |
| Friction loss | 7.5 | m | Pipe friction at design flow. |
| Minor losses | 2.1 | m | Fittings, valves and entrance/exit losses. |
| Residual pressure | 1.5 | bar g | Required pressure at the discharge. |
Assumptions this challenge makes
- The friction and minor losses are already evaluated at the design flow.
- The residual pressure is gauge pressure at the pump discharge reference.
- Water density is 1 000 kg/m3 and 1 bar equals 10.1972 m of water.
Your call
Your answer
Hints
- Convert the residual pressure from bar to metres of water before adding it.
- Total dynamic head is the sum of static lift, friction loss, minor loss and residual head.
- Keep all four terms in the same unit. Do not drop the residual pressure because it is not a physical lift.
Your answer Engine result
Where that comes from
Each limit, checked
Why
- Residual head is 1.5 x 10.1972 = 15.2958 m.
- Total dynamic head is 18 + 7.5 + 2.1 + 15.2958 = 42.8958 m.
- The residual pressure is a real head requirement even though it is not an elevation change. The pump must produce it at the discharge.
- The result is the pump duty head. Selecting a pump also requires the design flow, efficiency, NPSH margin and motor sizing.
- The calculation does not include suction-side conditions or a separate pressure drop in the discharge nozzle.
What this challenge does not establish
- Friction and minor losses are inputs; they must be computed for the actual pipe route and flow.
- The residual pressure is a project requirement, not a code-derived value.
- Suction lift, NPSH available, viscosity and solids are not modelled.
- The result is a head duty, not a pump selection or a guarantee of the operating point.