The specific speed (Ns) of a pump is given by the expression
1
\({{\rm{N}}_{\rm{s}}} = \frac{{{\rm{N}}{\sqrt{Q}}}}{{{{\rm{H_m}}^{5/4}}}}\)
2
\({{\rm{N}}_{\rm{s}}} = \frac{{{\rm{N}}{\sqrt{P}}}}{{{{\rm{H_m}}^{3/4}}}}\)
3
\({{\rm{N}}_{\rm{s}}} = \frac{{{\rm{N}}{\sqrt{Q}}}}{{{{\rm{H_m}}^{3/4}}}}\)
4
\({{\rm{N}}_{\rm{s}}} = \frac{{{\rm{N}}{\sqrt{P}}}}{{{{\rm{H_m}}^{5/4}}}}\)