The TSURUMI HSZ3.75S 110V is the automatic version of Tsurumi's HS-series portable dewatering pump (official classification: submersible pumps > portable dewatering pumps, automatic), supplied here in the single-phase 110V 50Hz version. It has an 80 mm (3-inch) discharge and a 0.75 kW single-phase capacitor-run motor, and comes with a factory-fitted float switch: the pump starts when the water rises to a preset level and stops when it falls back to the preset level. Eliminating dry-running cuts power consumption and extends the pump's operating life. With a urethane rubber semi-vortex impeller and a sintered-alloy agitator, it passes solids up to 7 mm and weighs 16.8 kg without the cable, making it a practical choice for unattended drainage of site water, basements and flooded areas.
"110V" is a supply version, not part of Tsurumi's model code: the factory model is HSZ3.75S in both cases, and Tsurumi UK offers the automatic (float) HS3.75S in single-phase 110V and 230V versions. The 110V version must run on a 110V 50Hz supply, which on construction sites usually comes from an isolating transformer.
Selection note: the HSZ3.75S has the same performance as the manual HS3.75S; the only difference is the automatic float control. For manual on/off operation, choose the HS3.75S 110V. For a 230V supply, choose the HSZ3.75S (230V). The HS/HSZ series are dewatering pumps, not sewage or slurry pumps: for settled sand, mud or bentonite, use the HSD2.55S slurry pump. If you need more flow at a lower head, consider the HSZ3.75SL 110V (580 L/min max. capacity, 10.8 m max. head).
Key features
- Automatic float-switch operation: a single float switch starts the pump at a preset high level and stops it at a preset low level, so it runs unattended and avoids the wear caused by dry-running.
- Shaft-mounted agitator prevents air lock: a sintered-alloy agitator on the shaft stops the air lock that vortex and semi-vortex pumps are prone to.
- Abrasion-resistant wear parts: parts exposed to wear are made of abrasion-resistant material, which Tsurumi says gives durability equivalent to its three-phase drainage pumps.
- Side discharge with spiral casing: solids pass through more smoothly, and the external side outlet helps draw solids in.
- Double inside mechanical seals: silicon carbide (SiC) faces running in an oil chamber, with Tsurumi's own Oil Lifter, which keeps the seal faces lubricated and cooled even when the oil drops to one third of its normal level.
- NBR V-ring dust seal: fitted on models of 0.55 kW and above, including this one.
- 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 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 the pump from scratching the floor.
Applications
- Construction sites: automatic pumping of excavations, trenches and temporary site water
- Buildings and facilities: level-controlled removal of water in basements, plant rooms and lift pits
- Storms and flooding: emergency drainage and unattended level control
- Maintenance works: temporary pumping during drain, manhole and tank maintenance
The pump is suited to water carrying a small amount of solids (up to 7 mm). It is not suitable for raw sewage, fibrous liquids, slurry, seawater or chemicals.
Performance
The 18 m maximum head is the head at near-zero flow, and the 300 L/min (about 18 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 hose friction loss) rises, so select the pump from the performance curve using your site's total head. Tsurumi's catalogue states that the standard and automatic models have identical performance.
Technical specifications
TSURUMI HSZ3.75S 110V technical specifications (50 Hz)
| Item | Specification |
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| General |
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| Model | HSZ3.75S (110V supply version) |
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| Type | Portable dewatering pump, automatic (submersible) |
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| Discharge bore | 80 mm (3 in) |
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| Discharge connection | Hose coupling (standard); male threaded coupling on special request |
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| Automatic control device | Float switch |
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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) | 300 L/min (approx. 18 m³/h) |
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| Max. solids passage | 7 mm |
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| Impeller | Semi-vortex, urethane rubber |
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| Agitator | Sintered alloy |
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| Electrical |
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| Motor output | 0.75 kW |
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| Power supply | Single-phase 110V 50Hz |
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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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| Synchronous speed | 3,000 min⁻¹ (50 Hz) |
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| Motor protection | Built-in circle thermal protector (CTP) |
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| Cable | 5 m PVC cable |
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| Seals and materials |
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| Shaft seal | Double inside mechanical seals, silicon carbide (SiC) faces, oil-lubricated, with Oil Lifter |
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| Lubricant | Turbine oil ISO VG32, 160 ml |
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| V-ring | Nitrile rubber (NBR) |
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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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| Dimensions and installation |
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| Dry weight (excl. cable) | 16.8 kg |
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| Dimensions (L × W × 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 level dimensions (FL1 min. / FL2 max.) | 150 mm / 475 mm |
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| Liquid limits (Tsurumi Europe data) |
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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. submersion depth | 20 m |
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Sources: Tsurumi single-phase portable pumps catalogue (IB101), Tsurumi Hong Kong and Tsurumi Global HSZ product pages, and Tsurumi Europe / Tsurumi UK HS series data (50 Hz). Tsurumi Hong Kong notes that published data may differ from the actual product, so obtain the delivery specification sheet before use. Rated current is as per the nameplate.
HSZ automatic models compared (110V)
Tsurumi HSZ automatic portable dewatering pumps compared (50 Hz)
| Model | Discharge | Power | Max. head | Max. capacity | Max. solids | Dry weight |
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| HSZ2.4S 110V | 50 mm | 0.4 kW | 12 m | 200 L/min | 7 mm | 11.3 kg |
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| HSZ2.75S 110V | 50 mm | 0.75 kW | 18 m | 230 L/min | 7 mm | 16.4 kg |
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| HSZ3.75S 110V (this product) | 80 mm | 0.75 kW | 18 m | 300 L/min | 7 mm | 16.8 kg |
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| HSZ3.75SL 110V | 80 mm | 0.75 kW | 10.8 m | 580 L/min | 7 mm | 19.6 kg |
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Optional accessories
- 80 mm (3-inch) discharge hose for the standard hose coupling.
- Male threaded coupling for pipe connection, available from the factory on special request.
- 110V site isolating transformer with a 110V 50Hz output rated for the motor.
Safety and installation
- Connect this pump only to a single-phase 110V 50Hz supply. Never connect it to 230V, and never run a 230V version on 110V.
- Use a correctly rated, earthed supply; an outlet with earth-leakage (RCD) protection is recommended. Electrical connection must be made by a registered electrical worker in line with local regulations.
- Make sure the float can move freely and cannot catch on the cable, a wall or debris. Allow at least 370 mm of space (F) and install to the FL1/FL2 levels shown on Tsurumi's dimension drawing.
- The built-in thermal protector (CTP) is a safeguard only. Do not let the pump run dry for long periods, and keep at least 90 mm of water for continuous running.
- Lift and lower the pump by its handle, never by the power cable. Protect the cable from damage; a damaged cable must be replaced or repaired before use.
- Stand the pump on firm ground or a raised platform so it does not sink into silt.
- Do not use it in flammable or explosive atmospheres or with flammable or corrosive liquids, and stay within 0–40 °C liquid temperature, pH 5–9 and 20 m maximum submersion depth.
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 the float switch and its cable regularly to make sure the float moves freely and is not tangled with debris.
- Isolate the power before inspection or servicing. Check and change the seal oil (turbine oil ISO VG32, 160 ml) periodically; if the oil is cloudy or contains water, have the shaft seals inspected promptly. The Oil Lifter only maintains lubrication down to one third of the normal oil level, so do not delay topping up.
