Specific Speed Ns

Shaft speedrpmFlow at BEPm³/hHead at BEPm

Specific speed Ns: 34.69 -

Changing the inputs requires JavaScript. The calculator above shows its default inputs and result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

N_s = \frac{N \cdot \sqrt{Q}}{H^{3/4}}

Symbol	Meaning	Unit
$N$	rpm	rpm
$Q$	Flow at BEP	m³/s
$H$	Head at BEP	m

Source: Hydraulic Institute ANSI/HI 9.1-9.5

In short

Dimensionless ratio that characterises pump type.

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