How to select pressure vessel based on pump data?

The sizing of potable pressure vessels can be calculated using the following formula:

V = K x Amax x ((Pmax+1) x (Pmin+1)) / ((Pmax-Pmin) x (Pprec+1))

K = working efficiency of pump (see table)

Amax = average flow (litre/min)

Pmax = Maximum working pressure of the pump (bar)

Pmin = Minimum working pressure of the pump (bar)

Pprec = Pre-charge pressure of the pressure vessel

Please note – always set the pre-charge air pressure of the vessels0.2 bar less than the pump pressure.