How to Select a Pump by Flow and Head

Flow is the liquid volume required per unit time. Total dynamic head is the sum of static elevation, pressure difference and velocity/friction losses expressed as liquid head. It is not simply the building height. Calculate normal, minimum and maximum cases and plot the system curve. The operating point is where that curve meets the pump curve. Prefer an efficient stable region and check minimum continuous flow, driver power and control method. Then verify liquid density, viscosity, temperature, vapour pressure, solids and corrosion. These can change power, performance, materials and pump type. Finally compare NPSHa with NPSHr using an appropriate engineering margin. Provide the piping sketch and each assumption with an enquiry so the duty point can be independently checked.