Most pump problems start with a pump selected for the wrong duty. Giving a supplier the right information takes a few minutes and avoids a pump that runs off its curve, cavitates or wears out early.
The duty point
State the flow rate and the total head the pump must deliver at that flow. Total head includes the static lift and the friction losses in the pipework. If the duty varies, give the minimum, normal and maximum flows.
Suction conditions and NPSH
Net positive suction head available (NPSHa) depends on the suction pipework, liquid level, liquid temperature and altitude. It must exceed the pump's NPSH required with a margin, or the pump will cavitate. Describe the suction side: flooded or suction lift, pipe size and length, and fluid temperature.
The fluid
- Fluid name, temperature, density and viscosity
- Solids content, particle size and specific gravity for slurries
- Chemical composition and pH, to select casing, impeller and seal materials
Drive and connections
Give the supply voltage and frequency, any hazardous-area classification, and the flange standard and pressure rating of the connecting pipework. If the pump replaces an existing one, nameplate photos and baseplate dimensions help a supplier offer a drop-in replacement.