Grundfos SEG.50.31.2.50B Pump
Spare Parts for SEG.50.31.2.50B Grinder Pump
Product Summary
The Grundfos SEG.50.31.2.50B is a 3.1 kW submersible grinder pump designed for pumping untreated sewage and wastewater in pressurized systems. Equipped with a patented grinder system, it reduces solids to small pieces, enabling the use of smaller discharge pipes. This robust pump supports both auto-coupling and free-standing installations, offering reliable operation in demanding environments.
- Patented Grinder System: A robust grinder system at the inlet effectively grinds solid particles, preventing clogging and ensuring reliable transport.
- High-Flow Design: The SEG.50 series features a DN 50 discharge port for higher flow requirements compared to the standard DN 40 models.
- SmartTrim Adjustment: The patented SmartTrim system allows for easy adjustment of the impeller clearance (Position 68) to maintain maximum efficiency.
- Clamp Connection: A stainless steel clamp (Position 92) secures the motor to the pump housing, facilitating tool-free disassembly for maintenance.
- Watertight Cable Plug: The cable plug (Position 1) is filled with polyurethane, ensuring a watertight seal that prevents liquid from entering the motor through the cable.
Spare Parts List
| Select | Qty | Part Number | Description | Material / Spec |
|---|---|---|---|---|
| 1 | 98453210 | Grinder System Kit (Head, Ring, Screw) | Hardened Steel | |
| 1 | 96645160 | Shaft Seal Complete (2.6-4.0 kW) | NBR / Mechanical | |
| 1 | 99346046 | Impeller Complete (w/ Key & Nut) | Cast Iron | |
| 1 | 96645275 | Shaft Seal Complete (2.6-4.0 kW) | FKM / Mechanical | |
| 1 | 96076125 | O-Ring Service Kit (2.6-4.0 kW) | NBR | |
| 1 | 96646062 | O-Ring Service Kit (2.6-4.0 kW) | FKM | |
| 1 | 99346058 | Shaft with Rotor Complete (3.1-4.0 kW) | Steel / Copper | |
| 1 | 96690428 | Lifting Bracket & Screw (2.6-4.0 kW) | Stainless Steel | |
| 1 | 96586753 | Oil (1 Litre) | Paraffinic Oil | |
| 1 | Pos. 44 | Grinder Ring | Hardened Steel | |
| 1 | Pos. 45 | Grinder Head | Hardened Steel | |
| 1 | Pos. 92 | Clamp | Stainless Steel | |
| 1 | Pos. 50 | Pump Housing (Volute) | Cast Iron (EN-GJL-200) | |
| 1 | Pos. 105 | Shaft Seal | Cartridge Type | |
| 1 | Pos. 1 | Cable Plug Assembly | Polyurethane / Rubber | |
| 2 | Pos. 193 | Oil Screw | Steel | |
| 1 | Pos. 68 | Adjusting Nut (Impeller) | Steel |
Exploded Parts Views
Key Technical Specifications
| Parameter | Value |
|---|---|
| Model / Curve | SEG.50.31.2.50B |
| Rated Power | 3.1 kW (4.2 HP) |
| Voltage / Frequency | 3 x 400-415 V / 50 Hz |
| Rated Current | See Motor Nameplate |
| Discharge Connection | DN 50 (Flange) |
| Impeller Type | Semi-Open with Grinder System |
| Installation Type | Submersible (Auto-Coupling or Free-Standing) |
Troubleshooting, Common Faults & Solutions
Pump does not start / Fuses blow
Likely Cause: Power supply failure, short circuit in cable/motor, or blocked impeller.
Action / Part: Check electrical installation and clean the Impeller (Pos. 49).
Pump runs but no liquid delivered
Likely Cause: Outlet/non-return valve blocked or air in the pump.
Action / Part: Clean valves and vent the pump by tilting it.
Motor protector trips shortly after start
Likely Cause: Incorrect impeller clearance or voltage drop.
Action / Part: Readjust impeller via Adjusting Nut (Pos. 68) or check voltage supply.
Below-standard performance
Likely Cause: Wrong direction of rotation or clogged impeller.
Action / Part: Swap two phases (3-phase pumps) or clean the impeller.
Pump is blocked
Likely Cause: The grinder system is worn or jammed.
Action / Part: Replace the Grinder System (Kit 98453210).
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