Grundfos SP 3A-25 supplies clean groundwater for domestic water systems, irrigation and pressure boosting, with a rated flow of 3m3/h (50L/min) at 111m head. This rated duty describes flow and head together. Actual flow depends on pumping lift, required outlet pressure and pipe resistance; the matching 50Hz curve helps assess expected flow for the installation.
The outlet is 32mm (1 1/4") Rp / BSP female thread. The pump handles clean, thin, non-aggressive water with a maximum sand content of 50g/m3. A built-in non-return valve reduces return flow when the pump stops.
The 240V single-phase three-wire motor uses an external starter, which is included with this package. The motor requires external protection that cuts power if the motor overloads. This protection can be incorporated in the starter/control box or provided separately, with settings matched to the motor nameplate.
For automatic operation, connect suitable tank-level or pressure controls. Where the water level could fall below the pump inlet, use dry-running protection to stop the pump before it draws in air. Extend the motor lead with correctly sized submersible cable and a suitable waterproof cable joint for the installation depth.
Keep the pump inlet submerged below the lowest water level reached while pumping. At least 0.5m of water above the inlet is recommended; greater submergence may be needed to maintain adequate pressure at the inlet. Maximum installation depth is 150m below the water surface. Install vertically with the motor below the pump and support the assembly with suitable pipework and installation hardware. Do not lift or suspend it by its electrical cable.
Liquid temperature is +2 to +40°C.
Water must pass around the outside of the motor at a speed of at least 0.15m/s (15cm/s) to cool it. In a wider bore, the same pump flow moves more slowly around the motor. Fit a cooling sleeve if the installation cannot provide the required speed; the sleeve directs water past the motor. The pump can run continuously without scheduled cooling stops while the inlet stays submerged and the specified flow, motor cooling and liquid temperature limits are maintained.
The pump and impellers are AISI 304 stainless steel. Multiple impeller stages build head through the pump, while water-lubricated bearings support the rotating assembly. The Grundfos MS402 submersible motor is rated IP68 with Class B insulation.
Two-year limited manufacturer warranty, subject to Grundfos warranty terms and applicable consumer rights.
SP 3A Official 50Hz Performance Curve
SP Installation & Operating Instructions
