The TSURUMI KTZ23.7-SEA seawater-resistant version is the KTZ23.7 submersible dewatering pump fitted with Tsurumi's optional Seawater-Resistant Kit. The KTZ series is Tsurumi's flagship line of three-phase, cast-iron dewatering pumps (officially classed as a general construction pump). The KTZ23.7 has a 50 mm (2-inch) discharge and a 3.7 kW motor. The kit adds galvanic anodes and a special seawater-resistant cast-iron impeller, so the pump can be used for drainage involving seawater, such as waterfront development, marine construction and aquaculture facilities.
According to Tsurumi, the Seawater-Resistant Kit provides about two years of service, depending on operating conditions. For longer-term use, check with the dealer first.
Selection note: The KTZ23.7-SEA is not a separate Tsurumi model; it is the KTZ23.7 with the Seawater-Resistant Kit. For freshwater site drainage only, the standard KTZ23.7 is sufficient, but the standard pump is not designed for long-term seawater use. This pump has no automatic operation, float or electrode control. Tsurumi's seawater pumps with all wetted parts in titanium and resin are a separate range, the TM series.
Key features
- Galvanic anodes protect the pump body: the anodes have a lower potential than the cast-iron body, so they corrode first and protect it. Tsurumi uses mainly aluminium anodes, with zinc only on the strainer stand. The anodes are consumed over time and must be replaced every two years.
- Special seawater-resistant cast-iron impeller: made from specially treated chromium cast iron with a potential slightly lower than the shaft, so the impeller corrodes slowly and protects the shaft. Its corrosive wear is about one tenth that of a conventional cast-iron impeller.
- Top-discharge, side-flow design: the motor stays cooled even when exposed to air, and the slim body fits confined spaces. With the seawater kit, keep the water level at 660 mm or above for continuous running.
- Multi-directional hose coupling: the discharge can be set vertical or inclined so the hose does not kink. On 3.7 kW models the kit includes a grey cast-iron hose coupling.
- Dual inside mechanical seals: silicon carbide (SiC) faces housed in the oil chamber, isolated from abrasion and corrosion. Tsurumi's Oil Lifter keeps the seals 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 overheating or overcurrent.
- Anti-wicking cable entry: stops water creeping into the motor by capillary action if the cable sheath is damaged; a cable clip protects against pulling.
Applications
- Waterfront development and coastal sites: excavation and temporary drainage of seawater or brackish water
- Marine construction: dewatering during offshore and coastal works
- Aquaculture facilities: seawater pumping
This is a dewatering pump for water carrying a small amount of sand and silt (up to 10% dry matter). It is not suitable for slurry, dense sand mixtures, desilting or dredging.
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. These figures are for the KTZ23.7 base model (50 Hz). For more flow, consider the 80 mm KTZ33.7-SEA seawater-resistant version or the 100 mm KTZ43.7-SEA seawater-resistant version.
Technical specifications
TSURUMI KTZ23.7-SEA seawater-resistant version technical specifications
| Item | Specification |
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| General |
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| Model | KTZ23.7-SEA (KTZ23.7 with Seawater-Resistant Kit) |
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| Series | KTZ (general construction pump, submersible dewatering) |
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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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| Seawater configuration | Galvanic anodes (mainly aluminium), special seawater-resistant cast-iron impeller |
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| Hydraulic performance (KTZ23.7 base model, 50 Hz) |
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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 | Dry-type induction motor, three-phase 2-pole, continuous-duty rated, insulation class F, IP68 |
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| Power supply | Three-phase (voltage as per nameplate) |
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| Speed | approx. 2,888 rpm (Tsurumi Europe 400 V 50 Hz data) |
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| Rated current | 8 A (Tsurumi Europe 400 V 50 Hz data; as per nameplate) |
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| Starting method | Direct-on-line (DOL); star-delta available on request |
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| Motor protection | Built-in circle thermal protector (CTP) |
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| Cable | 8 m, chloroprene rubber sheath |
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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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| Materials |
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| Impeller | Semi-open, special seawater-resistant cast iron (specially treated chromium cast iron) |
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| Suction cover | Ductile cast iron |
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| Casing, frame, motor housing | Grey cast iron |
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| Shaft | 420 stainless steel |
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| Galvanic anodes | Mainly aluminium; zinc on the strainer stand |
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| Liquid limits |
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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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| Dimensions (L × H) | 400 × 675 mm |
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| Dry weight | 60 kg (excl. galvanic anodes and cable) |
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| Min. continuous water level (C.W.L.) | 660 mm (level at which all galvanic anodes work effectively) |
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Sources: Tsurumi Seawater-Resistant Dewatering Pumps catalogue (IB115), KTZ/KTZE/KTD series catalogue (IB107), Tsurumi Hong Kong seawater-resistant pump information, and Tsurumi Europe KTZ23.7 data (400 V 50 Hz). Voltage and rated current of the Hong Kong supply version are as per the nameplate.
KTZ seawater-resistant models compared
The KTZ615-SEA is Jaco's seawater-resistant specification of the KTZ615, and its hydraulics are base-model data. Confirm its seawater-resistant configuration and minimum water level with Jaco before ordering.
Seawater-Resistant Kit contents
According to Tsurumi, the Seawater-Resistant Kit for KTZ 3.7 kW models includes:
- Galvanic anodes (with fittings and seal putty)
- Special seawater-resistant cast-iron impeller
- Grey cast-iron hose coupling (KTZ 3.7 kW models only)
- 304 stainless steel eye bolts (only for models fitted with steel eye bolts)
Please confirm the exact supply configuration when ordering.
Optional accessories
- Float switch and motor starter / control panel: the pump has no built-in level control, so unattended operation needs a float switch and a control panel with overload protection.
- Replacement galvanic anodes (every two years) and special seawater-resistant cast-iron impeller; ask the dealer for part numbers.
Safety and installation
- Three-phase supply only. Installation and wiring must be carried out by a registered electrical worker, with proper earthing and a motor starter that has overload and phase-loss protection. Check the voltage and current on the nameplate before connecting.
- Check the direction of rotation after connection.
- If the built-in thermal protector trips, find the cause of the overheating or overcurrent before running again. Isolate and lock out the power before any inspection or service.
- Never lift or lower the pump by its cable; use the eye bolt or handle with a chain or rope. The pump weighs 60 kg dry, so use suitable lifting equipment.
- Keep the water level at 660 mm or above for continuous running. Below this level, parts that are not submerged may corrode.
- Stand the pump on a stable base so it does not get buried in silt. Expect faster wear in sandy or corrosive service.
- Do not use with flammable liquids or in flammable or explosive atmospheres; the pump is not explosion-proof. Liquid temperature must not exceed 40 °C, and pH must be within 5–9.
Wear parts and routine checks
- Galvanic anodes: consumed over time; replace every two years. They are easy to replace and work immediately after replacement.
- Special seawater-resistant cast-iron impeller: corrodes slowly to protect the shaft; replace every few years, up to 10 years, depending on operating conditions.
- Mechanical seals, oil seal and suction cover: wear gradually with long running in sandy water.
- Check the oil in the oil chamber regularly (turbine oil ISO VG32, 1,250 ml). If the oil is cloudy or contains water, have the shaft seals inspected promptly.
