Specific speed The specific speed assigns every hydraulic design to an impeller type and shows how steep the pump curve is.
Input (at best efficiency point)
min⁻¹
m³/h
m
–
Result
Specific speed nq
– min⁻¹
–
nq = n · √Q / (H / i)0.75Q in m³/s, H in m, n in rpm
| Reference | Technical book, chap. 3.4.1 · The pump curve |
|---|---|
| Classification | n_q < 40 radial · 40–160 mixed-flow · > 160 axial |
| Wastewater | Typical wastewater impellers are in the range n_q 20–60. |