The TSURUMI LB-800A is a single-phase submersible dewatering pump from Tsurumi's LB-A series (officially classed as a portable dewatering pump, automatic operation type). It has a 50 mm (2-inch) discharge and a 0.75 kW 2-pole single-phase motor. A built-in electrode level relay starts the pump when water reaches the probe and stops it about one minute after the water falls below it, so no float switch and no attendant are needed. The slim body fits inside an 8-inch pipe or well casing, and the pump is built for site sumps, basement seepage and rain water carrying a small amount of sand and silt.
Selection note: the LB-800A is a dewatering pump, not a sewage or slurry pump. It handles water with some sand and silt and passes solids up to 6 mm, so it is not suitable for domestic sewage, wastewater with fibrous solids, or slurry. Its pump performance is identical to the standard LB-800; the only difference is the electrode auto-operation. For a smaller automatic model, see the LB-480A. If your site runs on a 110V supply, choose the LB-800A 110V version and confirm voltage and frequency on the nameplate.
Key features
- Electrode auto-operation: the pump runs while the probe is submerged. When the water drops below the probe, a timer starts and the pump stops after about one minute; it restarts when the water touches the probe again. This prevents dry-running and the rapid on-off cycling caused by a turbulent water surface. Tsurumi states up to 40% lower power use than non-automatic pumps (Tsurumi comparison).
- Top-discharge, flow-thru design: pumped water cools the motor efficiently, allowing continuous running at low water levels.
- Slim body: 223 mm overall diameter including the relay unit, so it fits inside an 8-inch pipe or well casing for well-point or deep-well dewatering.
- Multi-directional hose coupling: the discharge can be set vertical or inclined to stop the hose from kinking; loosen the cap nut on the coupling to change it.
- Dual inside mechanical seals: silicon carbide (SiC) faces running in an oil chamber, with Tsurumi's original Oil Lifter keeping the seals lubricated down to about one third of the normal oil level.
- NBR V-ring: acts as a dust seal that keeps abrasive particles away from the mechanical seal.
- Built-in circle thermal protector (CTP): cuts power on motor overheating or overcurrent and resets automatically once the motor cools.
- Anti-wicking cable entry: treated cable cores limit water creeping along the conductors into the motor.
- Abrasion-resistant materials: a semi-vortex urethane rubber impeller and a synthetic rubber casing. Tsurumi rates their durability as equivalent to its three-phase drainage pumps.
Applications
- Construction sites: draining pits, excavations and sumps, with automatic level-controlled pumping when unattended
- Basements and underground facilities: seepage and standing water removal
- Storms and flooding: rain water and emergency drainage
- Well-point and deep-well dewatering: installed inside an 8-inch pipe or well casing
For water only, at 0–40 °C (may contain sand and silt, up to 10% dry matter, pH 5–9). Not for seawater or salt water, oil, organic solvents, chemicals, or potable or drinking water.
Performance
At 50 Hz, the 15.0 m maximum head is the head at near-zero flow, and the 0.31 m³/min (310 L/min, about 18.6 m³/h) maximum capacity is the end point of the performance curve. The two do not occur together: actual flow falls as total head (static head plus hose friction loss) rises. Select the pump from the performance curve using your site's total head. Performance is identical to the standard LB-800. The 18.0 m maximum head quoted for 60 Hz builds does not apply to Hong Kong's 50 Hz supply.
Technical specifications
TSURUMI LB-800A technical specifications (50 Hz)
| Item | Specification |
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| General |
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| Model | LB-800A |
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| Series | LB-A (portable dewatering pump, automatic operation type) |
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| Discharge bore | 50 mm (2 in); 80 mm available on special order |
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| Discharge connection | Multi-directional hose coupling (standard); male threaded coupling on special order |
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| Automatic control | Electrode level relay unit (no float switch) |
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| Hydraulic performance |
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| Max. head (at zero flow) | 15.0 m |
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| Max. capacity (curve end point) | 0.31 m³/min (310 L/min / approx. 18.6 m³/h) |
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| Solids passage | 6 mm |
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| Starting water level | 170 mm (can be lowered with the optional extension probes) |
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| Stop | About 1 minute after the water falls below the probe |
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| Electrical |
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| Motor output | 0.75 kW |
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| Motor | Dry-type induction motor, continuous-duty rated, 2-pole, insulation class E |
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| Synchronous speed | 3,000 min⁻¹ (50 Hz) |
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| Power supply | Single-phase 50 Hz (voltage as per nameplate) |
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| Starting method | Capacitor run |
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| Motor protection | Built-in circle thermal protector (CTP), auto reset |
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| Cable | PVC, 5 m (Tsurumi catalogue standard) |
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| Seals and bearings |
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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 (non-additive), 155 ml |
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| V-ring | Nitrile butadiene rubber (NBR) |
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| Bearings | Shielded ball bearings |
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| Materials |
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| Impeller | Semi-vortex, urethane rubber |
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| Pump casing | Synthetic rubber |
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| Shaft | 403 stainless steel |
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| Liquid limits |
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| Liquid | Clean water or site, seepage and rain water containing sand and silt |
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| Liquid temperature | 0–40 °C |
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| pH | 5–9 |
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| Max. dry matter | 10% |
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| Max. use pressure | 0.2 MPa (about 20 m submergence plus discharge pressure) |
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| Dimensions and weight |
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| Dry weight (excl. cable) | 13.7 kg |
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| Height | 341 mm |
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| Overall diameter (incl. relay unit) | 223 mm |
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Sources: Tsurumi single-phase portable pumps catalogue (IB101), the Tsurumi LB series operation manual, the tsurumi.com.hk LB-A product page and Tsurumi Europe LB series data (50 Hz). Voltage, cable and rated current of the Hong Kong supply version are as per the nameplate; Tsurumi advises obtaining the delivery specification sheet before use.
LB series comparison
Tsurumi LB / LB-A series model comparison (50 Hz)
| Model | Operation | Power | Max. head | Max. capacity | Dry weight | 110V version |
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| LB-480 | Standard (non-automatic) | 0.48 kW | 11.0 m | 220 L/min | 10.4 kg | LB-480 110V |
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| LB-480A | Automatic (electrodes) | 0.48 kW | 11.0 m | 220 L/min | 11 kg | LB-480A 110V |
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| LB-800 | Standard (non-automatic) | 0.75 kW | 15.0 m | 310 L/min | 13.1 kg | — |
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| LB-800A (this product) | Automatic (electrodes) | 0.75 kW | 15.0 m | 310 L/min | 13.7 kg | LB-800A 110V |
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What's in the box
- LB-800A pump with attached cable and multi-directional hose coupling × 1
- Hose band × 1
- Operation manual × 1
Optional accessories
- Extension probes × 2: coil-spring type that can be cut to length to set a lower starting water level.
- 50 mm (2-inch) hose: layflat or suction hose, pushed fully onto the coupling and secured with the hose band.
- Earth leakage circuit breaker and thermal overload relay: purchased separately; set the overload relay to the nameplate rated current.
- Special order: male threaded coupling for pipe connection, or an 80 mm discharge.
Safety and installation
- Electrical connection must be made by a registered electrical worker in line with local regulations, with earthing, an earth leakage circuit breaker and a thermal overload relay. Never connect the earth wire to a gas pipe, water pipe, lightning rod or telephone earth.
- Supply voltage and frequency must match the nameplate, with voltage within ±10% of the rating. The 110V and 220V builds are different and cannot be swapped. On a generator, avoid running other equipment from the same set.
- Never lift, hang or drag the pump by its cable or by the level relay unit. Use the handle with a rope or chain rated for the pump weight. Do not scratch, fold, twist or bundle the cable, and never use a damaged cable, plug or outlet.
- Do not megger-test between the plug and the electrodes, or between the relay unit electrodes and the plug: this damages the relay.
- Never run the pump while anyone is in the sump or water, and never start it while it is suspended.
- Switch off and unplug before inspection or maintenance, and never work with wet hands.
- The thermal protector resets automatically: after a trip, disconnect the power and remove the cause. After a power cut, switch off the supply, because the pump restarts when power returns.
- Run the pump upright. If it may draw in mud, stand it on a concrete block. Lay the hose as straight as possible with its outlet above the water surface to avoid kinks, air lock and back-siphoning.
- Do not run against a closed valve, at abnormally low head or with a clogged impeller.
- The pump is neither explosion-proof nor dust-proof. Do not use it where toxic, corrosive or explosive gas may be present, and never use it for potable water.
- The surface gets hot during and just after operation. Do not touch it with bare hands.
Wear parts and routine checks
- Main wear parts: impeller, mechanical seals, V-ring, shaft sleeve, and packings/O-rings. Drawing in large amounts of mud causes premature wear.
- Daily: measure the operating current (within the rated current) and the supply voltage.
- Monthly: measure insulation resistance; reference value at least 1 MΩ, and at least 20 MΩ on a new or repaired pump.
- Oil: inspect every 1,000 hours or 6 months, and change every 2,000 hours or 12 months, whichever comes first, using 155 ml of turbine oil ISO VG32 (non-additive). Milky oil or oil mixed with water points to a failed mechanical seal that needs repair.
- Overhaul every 2 to 5 years, sooner under continuous duty. Mechanical seal inspection and replacement must be done by the dealer or a Tsurumi service centre.
- For long-term storage, lift the pump out, wash and dry it, and store it indoors. If it stays submerged, run it regularly (for example once a week).
