Input Parameters

Commercial / Industrial Mode

System Flow Rate (m³/h)

Pipe Internal Diameter (mm)

Total Pipe Length (m)

Water Temperature (°C)

Used for water density correction

Friction Coefficient λ

New steel pipe ≈ 0.015, Old steel pipe ≈ 0.02–0.03

Local Loss Ratio (fraction of friction loss)

Typical systems 0.2–0.5; more valves/elbows → higher value

Static Head (m)

Usually 0 for closed-loop systems; required for open systems

Formula Reference

Darcy-Weisbach equation:

h_f = λ × (L/d) × (v² / 2g)

Local loss estimation:

h_j = local loss ratio × h_f

Total head:

H = static head + h_f + h_j

Power estimation (pump efficiency η=0.7):

P = ρ g Q H / (1000 η) kW

How this pump head calculator works

This calculator estimates required pump head using Darcy-Weisbach friction loss plus an allowance for local losses. It then adds static head and estimates shaft power using water density and assumed pump efficiency.

Inputs explained

Flow rate and pipe diameter determine average velocity.
Pipe length and friction coefficient determine straight-pipe friction loss.
Local loss ratio approximates valves, fittings, bends, and equipment losses.
Static head accounts for elevation difference when applicable.
Water temperature adjusts density for the power estimate.

FAQ

Is this a pump selection tool?

It provides a preliminary head and power estimate. Final pump selection should use a full system curve and manufacturer pump curves.

What friction coefficient should I use?

The default is a typical preliminary value. Use project-specific pipe material, diameter, roughness, and Reynolds number for detailed design.

Does static head always matter?

In closed hydronic loops, static elevation may not define operating head in the same way as open systems. Apply it according to the system type.

Pump Head Calculator