Over the years , we usually come across User /Customer telling us give them a pump at X M3/hr at 6 bar or 8 bar, which sometime overestimated or guesswork without actual calculation. This resulted in over rated motor KW or oversized pump , which is wasteful in term of energy and pump size

Even , the working head is only 2.5 bar , customer specifiy much higher thinking it is better or as a safety factor

Not all engineers are fluid dynamics people , therefore it would be best a simple sketch showing piping diameter in the system and let pump suppliers work out the System Head closest to the requirement

user may consider Energy Efficient Drives / Motor , IE 2 or IE 3 , where many countries are phasing out IE 1 , with about 200 pumps in a palm oil refineries ,definitely much saving on energy cost

Operating with Frequency Invertors will also help a lot , that is supply as per demand .Not necessary for the Pumps to operate full load , especially in HVAC application ,There are hours where building is empty and coooling capacity can be reduced