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FluidsMay 9, 2026|3 min read

Head Loss

Head Loss is a core engineering term. Definition, usage notes, and a practical example.

Definition

Head loss is the energy lost to friction and local resistances during flow.

Why it matters

It is essential for pump selection, energy use, and process stability.

How it is used

In a design check, first define the relevant load, dimension, material, or flow condition. Then interpret this term by its role in the formula and compare it with limits.

Basic expression

Darcy loss = friction factor x length / diameter x velocity head

Example

Long pipe, small diameter, and many elbows increase head loss.

Formulas

Basic expression
Darcy loss = friction factor x length / diameter x velocity head