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Minor losses

In addition to friction along the pipe itself, valves, bends and constrictions cause an extra pressure loss, called a minor or local loss. The loss is proportional to the dynamic pressure and a loss coefficient that depends on the component's geometry, given in tables.

h_{minor} = K\dfrac{v^2}{2g}

minor loss

Symbols

$K$	loss coefficient (from a table)
$v$	speed in the pipe	m/s

Example

A valve has $K = 2.0$ and the speed in the pipe is $v = 1.8$ m/s. $h_{minor} = 2.0\cdot 1.8^2/(2\cdot 9.81) \approx 0.330$ m.

With many components, add up all the minor losses and the friction loss before computing the total pump power.

Practise pipe flow and dimensionless numbers for free →

← Darcy–Weisbach equation · Pump power →

Part of Fluid Mechanics: Pipe flow and dimensionless numbers.