The TSURUMI KTZ23.7 is a heavy-duty submersible dewatering pump from Tsurumi's KTZ series (officially classed as a general construction pump). It has a 50 mm (2-inch) discharge and a 3.7 kW 2-pole three-phase motor. KTZ is Tsurumi's flagship dewatering line: a cast iron body with a high-chromium cast iron impeller, built for construction, aggregate and mining work. It handles site water carrying sand and silt (up to 10% dry matter, pH 5–9, solids up to 8.5 mm).
With a maximum head of 36.5 m, the KTZ23.7 has the highest head of the 50–80 mm KTZ models, making it a good fit for sites that need to lift water higher or push it through a long hose run. It is a non-automatic model, operated through a control panel or manual switch.
Selection note: the KTZ33.7 (80 mm) and KTZ43.7 (100 mm) use the same 3.7 kW motor but trade head for flow; the KTZ23.7 is the high-head option. For automatic on/off by water level, choose the automatic KTZE23.7. For seawater or brackish water, choose the KTZ23.7-SEA seawater-resistant version fitted with the Seawater-Resistant Kit. The KTZ23.7 is a dewatering pump, not a slurry pump, so it is not suitable for settled sludge or dense sand slurry; for that duty, choose a slurry pump with an agitator such as the KTD33.7.
Key features
- Top-discharge, side-flow design: keeps the motor cooled even when it is exposed to air, and gives a slim body that fits confined spaces. Keep at least 150 mm of water (W1) for continuous running and do not run it dry for long periods.
- Multi-directional hose coupling: the discharge can be set vertical or inclined, so the hose does not fold or kink.
- High-chromium cast iron semi-open impeller: resists wear from abrasive particles. The shaft is quench-hardened where it contacts particles.
- Dual inside mechanical seals: silicon carbide (SiC) faces sitting in the oil chamber, isolated from abrasion and corrosion. Tsurumi rates SiC at 5× the corrosion, wear and heat resistance of tungsten carbide.
- Tsurumi Oil Lifter: keeps the seal faces lubricated and cooled even when the oil drops to about one third of the normal level. An NBR oil seal acts as a dust seal.
- Built-in circle thermal protector (CTP): cuts the motor circuit directly on excessive heat or overcurrent.
- Anti-wicking cable entry: stops water creeping into the motor by capillary action if the cable sheath is damaged, with a cable clip to protect against pulling.
Applications
- Construction sites: excavation and basement dewatering, temporary site drainage
- High-head drainage: deep pits and basements where water must be lifted high or sent through a long hose
- Aggregate pits and quarries: pit and sump dewatering (water only, not slurry transfer)
- Mines: general drainage duty
- Confined spaces: the slim body fits narrow shafts and small sumps
Performance
The 36.5 m maximum head is the head at near-zero flow, and the 450 L/min (about 27 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. If you need more flow at a lower head, consider the KTZ33.7 (900 L/min) or KTZ43.7 (1,440 L/min).
Technical specifications
TSURUMI KTZ23.7 technical specifications (50 Hz)
| Item | Specification |
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| General |
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| Model | KTZ23.7 |
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| Series | KTZ (general construction pump, heavy-duty submersible dewatering) |
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| Operation | Non-automatic |
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| Discharge bore | 50 mm (2 in) |
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| Discharge connection | Hose coupling (vertical or inclined) |
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| Hydraulic performance |
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| Max. head (at zero flow) | 36.5 m |
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| Max. capacity (curve end point) | 450 L/min (27 m³/h) |
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| Max. solids size | 8.5 mm |
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| Electrical |
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| Motor output | 3.7 kW |
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| Motor | Continuous-duty dry-type induction motor, 2-pole, insulation class F, IP68 |
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| Power supply | 3-phase (voltage as per nameplate) |
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| Speed | Synchronous 3,000 min⁻¹ (50 Hz); rated 2,888 rpm on the European 400 V 50 Hz version |
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| Rated current | 8 A (European 400 V 50 Hz version; Hong Kong supply as per nameplate) |
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| Starting method | Direct-on-line (D.O.L.); star-delta available on request |
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| Motor protection | Built-in circle thermal protector (CTP) |
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| Cable |
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| Standard cable length | 8 m |
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| Cable sheath | Chloroprene rubber |
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| Cable entry | Anti-wicking, with cable clip |
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| Seals and lubrication |
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| Shaft seal | Dual inside mechanical seals, silicon carbide (SiC) faces, in oil chamber, with Oil Lifter |
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| Oil seal | NBR (dust seal) |
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| Lubricant | Turbine oil ISO VG32, 1,250 ml |
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| Bearings | Shielded ball bearings |
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| Materials |
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| Impeller | Semi-open, high-chromium cast iron |
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| Suction cover | Ductile cast iron |
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| Casing, frame and motor housing | Gray cast iron |
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| Shaft | 420 stainless steel |
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| Liquid limits |
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| Liquid | Site drainage and muddy water carrying 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. submersion depth | 50 m |
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| Dimensions and weight |
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| Dry weight (excl. cable) | 60 kg |
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| Dimensions (catalogue A × A1 × B) | 342 × 283 × 675 mm (B = overall height) |
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| Min. water level for continuous running (W1) | 150 mm |
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Sources: Tsurumi KTZ/KTZE/KTD series catalogue (IB107) and Tsurumi Europe KTZ23.7 data (400 V 50 Hz). Max. head, max. capacity, rated speed, rated current, IP rating, bearings and liquid limits are taken from the European 50 Hz data. Voltage and rated current of the Hong Kong supply version are as per the nameplate.
KTZ series comparison: 50 mm and 3.7 kW models
Tsurumi KTZ series model comparison (50 Hz)
| Model | Discharge | Power | Max. head | Max. capacity | Dry weight |
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| KTZ21.5 | 50 mm | 1.5 kW | 21.5 m | 430 L/min | 34 kg |
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| KTZ22.2 | 50 mm | 2.2 kW | 26 m | 500 L/min | 35 kg |
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| KTZ23.7 (this product) | 50 mm | 3.7 kW | 36.5 m | 450 L/min | 60 kg |
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| KTZ33.7 | 80 mm | 3.7 kW | 29 m | 900 L/min | 60 kg |
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| KTZ43.7 | 100 mm | 3.7 kW | 18 m | 1,440 L/min | 60 kg |
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All models in the table pass solids up to 8.5 mm.
What's in the box
- KTZ23.7 pump with 8 m cable × 1
- Hose coupling × 1
Optional accessories
- Seawater-Resistant Kit: the KTZ23.7 is on Tsurumi's official list of models that accept the kit. It contains galvanic anodes (with fittings and seal putty), a seawater-resistant special cast iron impeller, a gray cast iron hose coupling and 304 stainless steel eye bolts where applicable. The kit-fitted version is listed as the KTZ23.7-SEA seawater-resistant version.
- Star-delta starting: available on request.
- Level control: the KTZ23.7 has no built-in automatic level control. For unattended running, pair it with a float switch and a motor starter or control panel with overload protection, or choose the automatic KTZE23.7.
- High-temperature version: for liquids above 40 °C, Tsurumi offers a separate high-temperature build rated up to 80 °C. Please contact us.
Safety and installation
- Lift and lower the pump by its handle or eye bolt with a chain or rope. Never lift it by the power cable, and protect the cable from pulling or cutting.
- Three-phase supply only. Wiring must be done by a registered electrical worker in line with local regulations, with proper earthing and a motor starter that has overload and phase-failure protection. Check the voltage and current on the nameplate before connecting.
- Check the rotation direction after connection.
- If the built-in thermal protector trips, find the cause of the overheating or overcurrent before restarting. Always isolate and lock out the power before inspection or servicing.
- Keep the water level at or above 150 mm (W1) for continuous running. Use a strainer and do not let the pump sink into silt.
- The standard model is not seawater-resistant; use the seawater-resistant version for seawater or brackish water. Do not pump liquids above 40 °C, outside pH 5–9, or flammable or explosive liquids, and do not use it in explosive atmospheres; the pump is not explosion-proof.
Wear parts and routine checks
- Main wear parts: impeller, suction cover, mechanical seals and oil seal. With long running in sandy water, the impeller and suction cover gradually wear and flow drops; wear is faster in abrasive or corrosive service.
- Regularly check the oil condition and level in the oil chamber (turbine oil ISO VG32, 1,250 ml). If the oil is cloudy or contains water, have the shaft seals inspected promptly.
