The TSURUMI HSZ2.75S is the automatic model of Tsurumi's portable dewatering pump range (official classification: submersible pumps > portable dewatering pumps). A single float switch, fitted to the pump, controls operation: when rising water lifts the float to the preset level, the switch closes and the pump starts; when the water falls back to the preset level, the pump stops, and the cycle repeats. The pump has a 50 mm discharge and a 0.75 kW single-phase, 2-pole, capacitor-run motor. A urethane rubber semi-vortex impeller and a sintered-alloy agitator let it pass solids up to 7 mm, making it well suited to unattended drainage of site water, basements, sumps and flood water.
Because the automatic model only runs when there is enough water, it uses less power and avoids the dry running that wears parts out early. Tsurumi states that the automatic HSZ and the standard HS models have identical performance. The HSZ2.75S has a ductile cast-iron casing, a nitrile rubber (NBR) V-ring dust seal and a built-in circle thermal protector (CTP). Dry weight is 16.4 kg.
Selection note: the HSZ2.75S is a dewatering pump, not a sewage or slurry pump. It is not suitable for raw sewage, wastewater with fibrous debris or settled sludge. If you prefer manual control without a float, choose the HS2.75S standard model, which has the same performance. If your site only has a 110V supply, choose the HSZ2.75S 110V version. For settled sand and mud, choose the HSD2.55S slurry pump with its high-chromium impeller and agitator.
Key features
- Float-switch automatic operation: one float switch starts the pump as the water rises and stops it as the water falls, cutting power use and preventing dry running.
- Side discharge with spiral casing: solids pass through the casing more smoothly, and the external side discharge outlet helps draw solids in and out.
- Urethane rubber semi-vortex impeller: abrasion-resistant, passing solids up to 7 mm.
- Shaft-mounted agitator (sintered alloy): prevents the air lock that vortex and semi-vortex pumps are prone to.
- Double inside mechanical seals: silicon carbide (SiC) faces running in an oil chamber, with Tsurumi's own Oil Lifter, which keeps lubricating and cooling the seal faces even when the oil drops to about one third of the normal level.
- NBR V-ring dust seal: standard on models of 0.55 kW and above, shielding the mechanical seals from abrasive grit.
- Built-in circle thermal protector (CTP): cuts the motor circuit directly 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 prevents condensation inside the motor housing. A cable clip protects against tugging.
- Resin stand: prevents scratching of the floor.
Applications
- Construction sites: automatic drainage of excavations, trenches and general site water
- Buildings and facilities: automatic drainage of basements, sumps and plant rooms
- Storms and flooding: emergency drainage that restarts by itself as water returns
- General works: temporary drainage for drain maintenance and small projects (water with a small amount of sand only)
Performance
At 50 Hz, the 18 m maximum head is the head at near-zero flow, and the 230 L/min (about 13.8 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. For more flow, consider the 80 mm HSZ3.75S (up to 300 L/min) or the high-volume, low-head HSZ3.75SL (up to 580 L/min).
Technical specifications
TSURUMI HSZ2.75S technical specifications (50 Hz)
| Item | Specification |
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| General |
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| Model | HSZ2.75S |
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| Type | Portable dewatering pump (submersible, automatic operation) |
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| Discharge bore | 50 mm |
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| Discharge connection | Hose coupling (standard); male threaded coupling for pipe connection on special request |
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| Hydraulic performance |
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| Max. head (at zero flow) | 18 m |
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| Max. capacity (curve end point) | 230 L/min (approx. 13.8 m³/h) |
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| Max. solids size | 7 mm |
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| Impeller | Semi-vortex |
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| Electrical and control |
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| Motor output | 0.75 kW |
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| Motor | Dry-type induction motor, 2-pole, insulation class E, continuous-duty rated |
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| Starting method | Capacitor run |
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| Power supply | Single-phase 50 Hz (voltage as per nameplate) |
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| Synchronous speed | 3,000 min⁻¹ (50 Hz) |
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| Motor protection | Built-in circle thermal protector (CTP) |
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| Automatic control | Float switch (fitted to the pump) |
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| Seals and lubrication |
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| Shaft seal | Double inside mechanical seals, silicon carbide (SiC) faces, oil-lubricated, with Oil Lifter |
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| V-ring | Nitrile rubber (NBR) |
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| Lubricant | Turbine oil ISO VG32, 160 ml |
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| Materials |
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| Impeller | Urethane rubber |
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| Agitator | Sintered alloy |
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| Pump casing | Ductile cast iron |
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| Shaft | 403 stainless steel |
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| Stand | Resin |
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| Cable |
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| Standard cable | PVC, 5 m |
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| Dimensions, weight and installation space |
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| Dry weight | 16.4 kg |
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| Dimensions (W × D × H) | 285 × 184 × 394 mm |
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| Discharge centre height | 218 mm |
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| Min. required space (F) | 370 mm |
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| Float levels (catalogue drawing MIN. FL1 / MAX. FL2) | 150 mm / 475 mm |
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| Min. water level for continuous running | 90 mm |
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| Liquid limits (published by Tsurumi Europe) |
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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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Sources: Tsurumi single-phase portable pumps catalogue (IB101) and the Tsurumi Hong Kong and Tsurumi Global HSZ series product pages. Performance is 50 Hz data; liquid limits are as published by Tsurumi Europe for the HS series. Tsurumi notes that website and catalogue data may differ from the actual product, so obtain the delivery specification sheet before use. Voltage of the Hong Kong supply version is as per the nameplate.
HSZ automatic series comparison
Tsurumi HSZ automatic series and HS2.75S standard model comparison (50 Hz)
| Model | Type | Discharge | Power | Max. head | Max. capacity | Min. required space F |
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| HSZ2.4S | Automatic | 50 mm | 0.4 kW | 12 m | 200 L/min | 340 mm |
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| HSZ2.75S (this product) | Automatic | 50 mm | 0.75 kW | 18 m | 230 L/min | 370 mm |
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| HSZ3.75S | Automatic | 80 mm | 0.75 kW | 18 m | 300 L/min | 370 mm |
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| HSZ3.75SL | Automatic (high volume, low head) | 80 mm | 0.75 kW | 10.8 m | 580 L/min | 350 mm |
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| HS2.75S | Standard (manual) | 50 mm | 0.75 kW | 18 m | 230 L/min | Not applicable |
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Optional accessories
- 50 mm (2-inch) discharge hose and hose clamps, to suit the standard hose coupling.
- Male threaded coupling for pipe connection, available from the factory on special request.
- RCD-protected socket or distribution box: connecting through an earth-leakage (RCD) device is recommended.
Safety and installation
- This pump has a single-phase capacitor-run motor. Connect it to a correctly rated, earthed 50 Hz supply that matches the nameplate voltage, preferably through an RCD. Never run a 230V unit on 110V, or the reverse.
- Electrical connection must be made by a registered electrical worker in line with local regulations.
- Allow at least 370 mm of space (F) in the sump or pit so the float switch can move freely. Make sure it cannot catch on the cable, hose or pit wall, or the pump may fail to start or stop.
- For continuous running, keep the water level at 90 mm or above. The built-in thermal protector is a safeguard only; do not run the pump dry for long periods.
- Lift and lower the pump by its handle, never by the power cable. If the cable is damaged, replace or repair it before use.
- Stand the pump on firm ground or a platform so it does not sink into silt.
- Do not use it in flammable or explosive atmospheres, and do not pump flammable or corrosive liquids, seawater or hot liquids.
- Always isolate the power before inspection or servicing.
Wear parts and routine checks
- Main wear parts: impeller, agitator, mechanical seals and V-ring. With long running in sandy water, the impeller gradually wears and flow drops.
- Check and change the seal oil (turbine oil ISO VG32, 160 ml) periodically. The Oil Lifter only maintains lubrication down to about one third of the oil level; if the oil is cloudy or contains water, have the shaft seals inspected promptly.
- Regularly check that the float switch moves freely and is free of mud build-up, and inspect the cable sheath and cable entry for damage.
