The TSURUMI 50B2.75 is a submersible sewage pump from Tsurumi's B series (officially classed as a sewage and wastewater pump with a channel impeller). It has a 50 mm discharge and a 0.75 kW 2-pole three-phase dry-type motor. Its grey cast-iron semi-open single-channel impeller passes solids up to 45 × 20 mm and is designed to minimise trouble from clogged solids and fibrous matter, making it suitable for sewage and wastewater containing solids (0–40 °C, pH 5–9). At just 25 kg dry, it is a compact choice for building sewage sumps and small pump rooms.
Selection note: the 50B2.75 is the standard-head three-phase model. The 50B2.75H is the high-head version (15.2 m max head) and the 50B2.75S is the single-phase version, both also 50 mm and 0.75 kW, so choose by your system head and power supply. This is a non-clog sewage and wastewater pump, not a slurry pump, and it is not suitable for dense sand, slurry or desilting work. The standard model is not seawater-resistant and is not rated for liquids above 40 °C; seawater-resistant and high-temperature (up to 80 °C) versions are special-order options.
Key features
- Anti-clogging channel impeller: the impeller itself forms a channel, so solids and fibrous matter are less likely to clog inside the pump. This model uses a semi-open single-channel impeller with 45 × 20 mm solids passage.
- Dual inside mechanical seals: silicon carbide (SiC) faces isolated in an oil chamber, away from the pumped liquid, which reduces the risk of failure from dry running and adhering matter.
- Tsurumi Oil Lifter: keeps the seal faces lubricated and cooled even when the oil drops to one-third of its normal level, extending seal life.
- Built-in circle thermal protector (CTP): directly cuts the motor circuit on overheating or overcurrent.
- Anti-wicking cable entry: stops water creeping into the motor by capillary action if the cable sheath is damaged or the cable end is submerged, and limits condensation inside the motor housing.
- Continuous-duty dry-type motor: 2-pole induction motor, IP68.
- Guide rail fitting available (TOS50B2.75): the pump can be lifted out and lowered back along guide pipes, so maintenance does not require entering the sump.
Applications
- Buildings and facilities: sewage and wastewater discharge from sumps and small sewage pump rooms
- Sewage and wastewater treatment: transfer of wastewater carrying solids and fibrous matter
- Industrial sites: industrial wastewater drainage
- Flood control: stormwater and floodwater drainage
- Irrigation and recreation facilities: drainage duties
Performance
The 12 m maximum head is the head at near-zero flow, and the 435 L/min (about 26.1 m³/h) maximum capacity is the end point of the 50 Hz performance curve. The two do not occur together: actual flow falls as total head (static head plus pipe friction loss) rises. Select the pump from Tsurumi's 50 Hz performance curve using your system's total head; Hong Kong mains is 50 Hz, so do not use 60 Hz data. For more head, consider the 50B2.75H (15.2 m max head); for more flow, consider the 80 mm 80B21.5 (1.5 kW, 1,000 L/min max capacity).
Technical specifications
TSURUMI 50B2.75 technical specifications (50 Hz)
| Item | Specification |
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| General |
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| Model | 50B2.75 |
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| Series | B series (sewage and wastewater pump, channel impeller) |
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| Discharge bore | 50 mm |
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| Discharge connection | Threaded oval flange (guide rail version: threaded JIS 10K flange) |
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| Hydraulic performance |
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| Max. head (at zero flow) | 12 m |
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| Max. capacity (curve end point) | 435 L/min (26.1 m³/h) |
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| Solids passage | 45 × 20 mm |
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| Impeller | Semi-open single-channel |
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| Electrical |
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| Motor output | 0.75 kW |
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| Motor | 2-pole dry-type induction motor, continuous duty, IP68, insulation class E or F (as per nameplate) |
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| Synchronous speed | 3,000 min⁻¹ (50 Hz) |
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| Power supply | 3-phase 50 Hz (voltage as per nameplate) |
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| Starting method | Direct-on-line (DOL) |
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| Motor protection | Built-in circle thermal protector (CTP) |
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| Cable | 6 m, PVC |
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| Shaft seal and lubrication |
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| Shaft seal | Dual inside mechanical seals, silicon carbide (SiC) faces, oil-lubricated, with Oil Lifter |
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| Lubricant | Turbine oil ISO VG32, 440 ml |
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| Materials |
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| Impeller | Grey cast iron |
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| Pump casing, suction cover | Grey cast iron |
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| Motor frame | Grey cast iron |
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| Shaft | 420 stainless steel |
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| Liquid limits |
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| Liquid | Sewage and wastewater |
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| Liquid temperature | 0–40 °C |
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| pH | 5–9 |
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| Dimensions and weight |
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| Dimensions, free-standing (L × W × H) | 405 × 250 × 439 mm |
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| Dimensions, guide rail (TOS50B2.75) | 621 × 250 × 479 mm |
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| Dry weight (excl. cable) | Free-standing 25 kg; guide rail 24 kg |
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| Lowest running water level | 170 mm |
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Sources: Tsurumi B-series catalogue (IA100) and Tsurumi Europe B-series data (50 Hz; max. head, max. capacity, solids passage, liquid limits, IP rating and lowest running water level). Voltage and rated current of the Hong Kong supply version are as per the nameplate and confirmation from the Hong Kong agent.
B series 50 mm model comparison
Tsurumi B series 50 mm model comparison (50 Hz)
| Model | Supply | Power | Max. head | Max. capacity |
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| 50B2.4 | Three-phase | 0.4 kW | 9 m | 263 L/min |
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| 50B2.4S | Single-phase | 0.4 kW | approx. 9 m | approx. 263 L/min |
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| 50B2.75 (this product) | Three-phase | 0.75 kW | 12 m | 435 L/min |
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| 50B2.75H | Three-phase (high head) | 0.75 kW | 15.2 m | 360 L/min |
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| 50B2.75S | Single-phase | 0.75 kW | approx. 15.2 m | approx. 360 L/min |
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Each single-phase model shares the 50 Hz performance curve of its three-phase counterpart (50B2.4S with 50B2.4; 50B2.75S with 50B2.75H); the approximate values are taken from that curve.
Optional accessories
- Guide rail fitting TOS50B2.75: includes a duckfoot bend, guide support with bolts and nuts, guide hook, 5 m lifting chain with shackles and a JIS 10K flange. Guide pipes are not supplied.
- Float switches: for level control through an external control panel. The MC-2 is a heavy-duty float switch with a shock absorber and selectable NO/NC contact, suited to liquids with suspended solids and scum; the MT-1 is an economy teardrop float with an integrated counterweight and SPDT switch, for emptying or filling control.
- External control panel: three-phase pumps must be connected through a control panel with overload protection.
- Mating flange: the free-standing discharge is a threaded oval flange and the guide rail version uses a JIS 10K flange; confirm the flange standard before connecting to local pipework.
Safety and installation
- Installation and electrical connection must be carried out by a registered electrical worker in line with local regulations. Earth the pump correctly and fit overload and earth-leakage protection in the control panel; set the overload relay to the nameplate rated current.
- Check that the rotation direction is correct before running a three-phase pump for the first time.
- After the built-in CTP trips, the motor may restart automatically once it cools. Always isolate the power before inspection or servicing.
- Keep the liquid at or above the lowest running water level (170 mm) and avoid prolonged dry running.
- Lift the pump by its handle or a lifting chain. Never lift it by the power cable.
- Never submerge the cable end or cut or damage the cable sheath; the anti-wicking cable entry is a safeguard only.
- Do not touch the pump or put your hands near the suction while it is energised. Follow confined-space and toxic-gas (e.g. hydrogen sulphide) precautions when working in sewage sumps; a guide rail fitting lets you lift the pump out for maintenance without entering the sump.
- Use only for sewage and wastewater at 0–40 °C and pH 5–9. Do not pump flammable, explosive or strongly corrosive liquids.
Wear parts and routine checks
- Main wear parts: impeller, suction cover and mechanical seals.
- Check the oil condition and level in the oil chamber regularly (turbine oil ISO VG32, 440 ml) to protect the mechanical seals. If the oil is cloudy or contains water, have the shaft seals inspected promptly.
- Regularly check the impeller for fibre wrapping or wear, and the cable sheath for damage.
