Start with the flow you need at the outlet. Allow for the height the water must rise and the losses through pipes and fittings, then check the working point on the pump curve.
Compare CP200 and CP400 when cast iron suits the installation. CP400SL has a cast stainless steel casing. The 20m figures in the summary give a common comparison point. The chart shows how flow changes at other heads.
Allow for separate controls if the pump needs to start and stop automatically.
Fill the pump casing and suction line with clean water before starting. Keep suction joints airtight. Fit a foot valve at the intake for suction lift or a long suction line, following Orange’s installation instructions.
Orange Pumps catalogue
Orange Pumps installation instructions