The TSURUMI LB-800 is a single-phase portable dewatering pump from Tsurumi's LB series (officially listed under Submersible Pumps > Dewatering > Portable Dewatering Pumps). It has a 50 mm (2-inch) discharge and a 0.75 kW 2-pole single-phase motor. The slim body fits inside an 8-inch pipe or well casing, and the semi-vortex urethane rubber impeller and synthetic rubber casing suit site water carrying sand and silt, seepage water and rain water, with a 6 mm solids passage.
Selection note: the LB-800 is a dewatering pump, not a sewage or slurry pump. It is for water only (sand and silt up to 10% dry matter) and is not suitable for sewage with fibrous solids, septic tanks or slurry transfer. The LB-800 is the standard (non-automatic) model; for automatic start/stop by water level, choose the LB-800A automatic type with its electrode level relay unit.
Key features
- Top discharge, flow-thru design: water passes around the motor for maximum cooling, so the pump can run continuously at low water levels and has extended dry-run capability.
- Slim body: fits inside an 8-inch pipe or well casing for well-point and deep-well dewatering.
- Multi-directional hose coupling: set the discharge vertical or inclined so the hose does not fold; loosen the cap nut on the coupling to change the direction.
- Dual inside mechanical seals: silicon carbide (SiC) faces running in an oil chamber, with Tsurumi's original Oil Lifter keeping the seal faces lubricated down to about one third of the normal oil level.
- NBR V-ring dust seal: keeps abrasive particles away from the mechanical seal.
- Built-in circle thermal protector (CTP): trips on overheating or overcurrent, including overheating from dry-running, and resets automatically once cooled.
- Anti-wicking cable entry: treated cable cores limit water creeping along the cable into the motor.
- Abrasion-resistant wear parts: Tsurumi rates their durability as equivalent to its three-phase drainage pumps.
Applications
- Construction sites: excavation, trench and basement dewatering
- Well-point and deep-well dewatering: fits inside 8-inch pipe or well casing
- Seepage and rain water: underground seepage and storm water removal
- General drainage: site water containing sand and silt (water only, not sewage or slurry)
Performance
At 50 Hz the LB-800 has a maximum head of 15.0 m, which is the head at near-zero flow, and a maximum capacity of 0.31 m³/min (310 L/min, about 18.6 m³/h), which 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, so select the pump from the performance curve using your site's total head. 60 Hz builds have different performance, so check the voltage and frequency on the nameplate. For lighter duty, consider the LB-480 (0.48 kW, 11.0 m max head).
Technical specifications
TSURUMI LB-800 technical specifications (50 Hz)
| Item | Specification |
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| General |
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| Model | LB-800 |
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| Series | LB (portable dewatering pump, standard non-automatic model) |
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| Discharge bore | 50 mm (2 in); 80 mm available on special order |
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| Discharge connection | Hose coupling (standard, vertical or inclined); male threaded pipe coupling on special order |
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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 / 18.6 m³/h) |
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| Solids passage | 6 mm |
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| Electrical |
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| Motor output | 0.75 kW |
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| Motor | Continuous-duty dry-type induction motor, 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 (voltage as per nameplate); supply within ±10% of the rated nameplate voltage |
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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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| Oil seal | V-ring, nitrile butadiene rubber (NBR) |
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| Lubricant | Turbine oil ISO VG32, 155 ml |
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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 | Water (site water containing sand and silt, seepage water, rain water) |
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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) | 13.1 kg |
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| Height | 341 mm |
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| Continuous running water level | 50 mm |
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| Pipe / well fit | Fits inside an 8-inch pipe or well casing |
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Sources: Tsurumi single-phase portable pumps catalogue (IB101), Tsurumi LB series operation manual and Tsurumi Europe LB series data (50 Hz). Voltage, frequency and cable of the Hong Kong supply version are as per the nameplate; Tsurumi advises obtaining the delivery specification sheet before use, as published specifications may change.
LB series comparison
Tsurumi LB series portable dewatering pump comparison (50 Hz)
| Model | Operation | Power | Max. head | Max. capacity | Dry weight |
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| LB-480 | Standard (manual) | 0.48 kW | 11.0 m | 220 L/min | 10.4 kg |
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| LB-480A | Automatic (electrodes) | 0.48 kW | 11.0 m | 220 L/min | 11 kg |
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| LB-800 (this product) | Standard (manual) | 0.75 kW | 15.0 m | 310 L/min | 13.1 kg |
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| LB-800A | Automatic (electrodes) | 0.75 kW | 15.0 m | 310 L/min | 13.7 kg |
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Single-phase 110V versions: LB-480 110V, LB-480A 110V and LB-800A 110V. 110V and 220V units are different builds and are not interchangeable.
What's in the box
- LB-800 pump with attached cable and hose coupling × 1
- Hose band × 1
- Operation manual × 1
Optional accessories
- External float switch: the LB-800 has no automatic operation of its own; an external float switch can be added for automatic start/stop.
- Male threaded pipe coupling: available on special order for pipe instead of hose connection.
- 80 mm discharge: available on special order.
- Earth leakage circuit breaker (ELCB) and thermal overload relay: set to the nameplate rated current; purchased separately.
Safety and installation
- Electrical work must be carried out by a registered electrical worker to local regulations, with earthing, an ELCB and a thermal overload relay. Never connect the earth wire to a gas pipe, water pipe, lightning rod or telephone earth.
- Never lift, suspend or drag the pump by its cable; use the handle with a rope or chain rated for the pump weight. Do not scratch, fold, twist, modify or bundle the cable, and never use a damaged cable, plug or outlet.
- Never run the pump while anyone is in the sump or water, and never start it while it is suspended, as it may jerk.
- Switch off and unplug before inspection or maintenance, and do not handle it with wet hands.
- The motor protector resets automatically: after a trip, disconnect the power and remove the cause. After a power cut, switch off the supply, otherwise the pump will restart when power returns.
- Do not run dry or against a closed valve; keep about 50 mm of water for continuous running, and do not run at abnormally low head or with a clogged impeller.
- Operate the pump upright. If it may draw in mud, stand it on a concrete block. Lay the discharge hose straight with its outlet above the water surface to avoid kinks, air lock and backflow or siphoning.
- For water at 0–40 °C only. Never use for oil, seawater or salt water, organic solvents or potable water. The pump is not explosion-proof or dust-proof; do not use it where toxic, corrosive or explosive gas is present.
- The surface gets hot during and right after operation; do not touch it with bare hands.
Wear parts and routine checks
- Daily: measure the operating current (must be within the rated current) and the supply voltage (within ±10% of the rated voltage).
- Monthly: measure insulation resistance (reference value for a pump in service: 1 MΩ minimum); if it is markedly lower than at the last check, have the motor inspected. A new or repaired pump must read at least 20 MΩ.
- Oil inspection: every 1,000 operating hours or 6 months, whichever comes first. Milky oil or oil mixed with water most likely indicates a failed mechanical seal, and the pump must be dismantled and repaired.
- Oil change: every 2,000 operating hours or 12 months, whichever comes first, with 155 ml of non-additive turbine oil ISO VG32. Replace the oil plug packing or O-ring at every oil inspection and change.
- Periodic replacement parts: mechanical seal (when the oil turns milky; yearly replacement recommended), V-ring (when worn and at every disassembly), packings and O-rings (at every disassembly or inspection) and shaft sleeve (when worn). Mechanical seal inspection and replacement need special tools, so refer it to your dealer or a Tsurumi office.
- Overhaul: every 2 to 5 years even if the pump appears normal; pumps in continuous service may need it sooner.
- Drawing in large amounts of mud causes premature wear and can lead to malfunction, current leakage and electric shock.
