The TSURUMI KTZ33.7-SEA Seawater-Resistant Version is the KTZ33.7 submersible dewatering pump from Tsurumi's KTZ series (officially classed as a general construction pump), fitted with Tsurumi's optional Seawater-Resistant Kit. It has an 80 mm (3-inch) discharge and a 3.7 kW 2-pole three-phase motor, delivers up to 29 m of head and up to 900 L/min, and passes solids up to 8.5 mm. The kit adds galvanic anodes (mainly aluminium) and a seawater-resistant special cast iron impeller, so the standard cast iron pump can be used to drain seawater and brackish water on waterfront construction sites and marine works.
According to Tsurumi, a pump fitted with the kit gives about two years of service, depending on operating conditions. If you need it for longer, consult the dealer first. The galvanic anodes need replacing every two years, and the special impeller every few years up to ten, depending on conditions.
Selection note: the KTZ33.7-SEA is the KTZ33.7 fitted with Tsurumi's Seawater-Resistant Kit; it is not a separate Tsurumi model. The standard KTZ33.7 has no galvanic anodes or seawater-resistant impeller and is not recommended for long-term use in seawater or brackish water. Nor is this a permanent titanium or resin seawater pump: the anodes and impeller are consumables that must be replaced periodically. The KTZ is a dewatering (muddy-water) pump, not a slurry pump, so it is not suitable for settled sludge or dense sand slurry.
Key features
- Galvanic anodes protect the pump body: the anodes have a lower potential than cast iron and steel, so they corrode first and protect the body. Tsurumi mainly uses aluminium for its better anti-corrosion performance per unit weight, with zinc only on the strainer stand, which is exposed to water-flow wear. The anodes only work when submerged.
- Seawater-resistant special cast iron impeller: made from specially treated chromium cast iron with a potential slightly lower than the shaft, so it corrodes gradually and protects the shaft. Tsurumi puts its corrosive wear at about one tenth of a conventional cast iron impeller. While the pump runs, the anodes cannot protect rotating parts, which is why this impeller is needed to protect the shaft.
- Top-discharge, side-flow design: the motor stays cooled even when exposed to air, and the body is slim enough for confined spaces. The hose coupling can be set for vertical or inclined discharge to keep the hose from folding.
- Double inside mechanical seals: silicon carbide (SiC) faces sit in the oil chamber, isolated from abrasion and corrosion. Tsurumi's Oil Lifter keeps the seals lubricated and cooled down to about one third of the normal oil level, and 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, with a cable clip to resist pulling.
Applications
- Waterfront construction sites: draining seawater or brackish water seeping into excavations and basements
- Marine construction projects: temporary dewatering and drainage during marine and coastal works
- Waterfront development projects: site water and brackish water removal
Performance
The 29 m maximum head is the head at near-zero flow, and the 900 L/min (about 54 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 head, consider the KTZ23.7-SEA Seawater-Resistant Version (36.5 m); for more flow, the KTZ43.7-SEA Seawater-Resistant Version (1,440 L/min).
Technical specifications
TSURUMI KTZ33.7-SEA Seawater-Resistant Version technical specifications
| Item | Specification |
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| General |
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| Model | KTZ33.7-SEA (KTZ33.7 with Seawater-Resistant Kit) |
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| Series | KTZ (general construction pump, submersible dewatering) |
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| Discharge bore | 80 mm (3 in) |
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| Discharge connection | Gray cast iron hose coupling (supplied in the kit) |
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| Hydraulic performance (50 Hz) |
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| Max. head (at zero flow) | 29 m |
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| Max. capacity (curve end point) | 900 L/min (54 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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| Synchronous speed | 3,000 min⁻¹ (50 Hz) / 3,600 min⁻¹ (60 Hz) |
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| Power supply | Three-phase (voltage 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 | Double 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, seawater-resistant special cast iron (supplied in the kit) |
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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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| 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) | 405 × 675 mm |
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| Dry weight | 60 kg (excluding galvanic anodes and cable) |
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| Min. water level for continuous running (C.W.L.) | 660 mm (needed for all galvanic anodes to work) |
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Sources: Tsurumi Seawater-Resistant Dewatering Pumps catalogue (IB115), KTZ/KTZE/KTD series catalogue (IB107) and Tsurumi Europe KTZ33.7 data (liquid limits, IP rating, 50 Hz performance). Voltage and rated current of the Hong Kong supply version are as per the nameplate.
Seawater-Resistant Kit contents
- Galvanic anodes (with fittings and seal putty)
- Seawater-resistant special cast iron impeller
- Gray cast iron hose coupling (3.7 kW KTZ models only)
- 304 stainless steel eye bolts (only on models originally fitted with steel eye bolts)
KTZ seawater-resistant versions 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.
Optional accessories
- Float switch and control panel: the KTZ has no built-in level control. For automatic on/off, pair it with a float switch and a motor starter or control panel with overload protection. Three-phase pumps must be connected through a control panel.
- Motor overload protector or control panel, set to the nameplate rated current.
- Replacement galvanic anodes and seawater-resistant special cast iron impeller for scheduled replacement. Ask the dealer for part numbers.
Safety and installation
- Three-phase supply only. Wiring must be done by a registered electrical worker in line with local regulations, with proper earthing, earth-leakage protection and a motor starter with overload and phase-loss protection. Check the voltage and current on the nameplate before connecting.
- Check the rotation direction before first use. If it turns the wrong way, have an electrician swap two phases.
- If the built-in thermal protector trips, find the cause of the overheating or overcurrent before running the pump again. Always isolate and lock out the power before inspection or servicing.
- Lift the pump by its handle or eye bolts with a chain or rope. Never lift it by the power cable, and protect the cable from pulling and cuts.
- For continuous running, keep the water level at or above 660 mm (C.W.L.). Below that level, parts that are not submerged may corrode.
- Use a strainer and keep the pump from being buried in silt. Expect faster wear in sandy or corrosive service.
- The pump is not explosion-proof. Do not use it for flammable or explosive liquids or atmospheres, drinking water, oils or solvents. Liquid temperature must not exceed 40 °C.
Wear parts and routine checks
- Galvanic anodes: replace every two years.
- Seawater-resistant special cast iron impeller: replace every few years up to ten, depending on conditions.
- Periodically check the impeller and suction cover for wear, and the cable sheath for damage.
- 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.
