For a pump with no air vessel, stroke length $=300mm,$ piston diameter $=125mm,$ suction pipe diameter $=75mm,$ length of suction pipe $=6m$ and suction head $=3m.$ Atmospheric pressure $=10\mathrm{.}3m$ of water and separation may be assumed to occur when the absolute pressure head in the cylinder falls below $2\mathrm{.}5$ m of water.

Calculate the maximum speed at which the pump may be run if separation is to be avoided.