Grundfos SP 3A pumps supply clean groundwater for domestic water systems, irrigation and pressure boosting. Rated flow is 3m3/h (50L/min), with rated heads from 27m to 280m across these models. Each head rating is stated at that same rated flow. 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 two-wire versions use MS402 motors at 0.37-0.75kW and ULTRA motors at 1.1kW. Two-wire versions have their starting equipment in the motor. The 240V single-phase three-wire packages include the external starter for their motor.
MS402 single-phase motors at 0.37-0.75kW have built-in thermal protection that cuts power if the motor overheats. The 1.1kW single-phase MS402 motor also requires external current protection. The 1.5kW single-phase MS402 and 2.2kW single-phase MS4000 motors require external motor protection, provided in a suitable starter/control box or as a separate device. All 415V three-phase versions require a motor-protection device that cuts power if the motor overloads. Match the protection settings 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 below the water surface is 150m for MS402 and ULTRA motor versions, and 600m for MS4000 versions. 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.
For the MS402 and MS4000 motor versions, 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. MS402 motors have IP68 protection and Class B insulation; MS4000 motors have IP68 protection and Class F insulation.
Grundfos motor versions have a two-year limited manufacturer warranty. The Australian catalogue specifies a one-year motor warranty for ULTRA motors. Warranty terms and applicable consumer rights apply.
SP 3A Official 50Hz Performance Curve
SP Installation & Operating Instructions
