What is the definition of Pumping Speed?

Pumping speed S (l/s, m³/h, cm³/s )
The pumping speed is the volumetric flow through the pump’s intake port.
S = (dV)/dt
If S remains constant during the pumping process, then one can use the difference quotient instead of the differential quotient:
S =(∆V)/∆t

(A conversion table for the various units of measure used in conjunction
with pumping speed is provided below).