The TSURUMI NK3-22L is a portable dewatering pump from Tsurumi's NK series, with an 80 mm (3-inch NPT male) discharge and a 2.2 kW (3 HP) single-phase 2-pole motor. Unlike the rubber-cased NK models, the NK3-22L has a cast-iron casing and a high-chrome cast-iron impeller and is built for high flow. It is aimed at construction-site drainage and rental fleets, handles rain water, ground water and sand-carrying water, and passes solids up to 8.5 mm.
The NK3-22L is a Tsurumi America model and is documented in a 60 Hz version only; it is not part of the Tsurumi Hong Kong or global catalogue, where the equivalent model is the NK4-22L. All figures below come from Tsurumi America data. Voltage and frequency are as per the nameplate, so check the nameplate before connecting it to a 50 Hz supply in Hong Kong.
Selection note: the NK series is a dewatering pump, not a sewage pump or a slurry pump. It is not suitable for raw sewage with fibrous solids, settled sludge or dense sand slurry. The NK4-22, also 2.2 kW, delivers more head (26 m max. at 60 Hz) but less flow; the NK3-22L trades head (about 18 m) for flow of up to about 800 L/min. Choose by the total head and flow your site needs.
Key features
- Top-discharge, flow-through design: the motor stays cooled even when partly exposed, so the pump can run for long periods at low water levels. The slim body fits into narrow sumps.
- Wear-resistant hydraulics: high-chrome cast-iron impeller, cast-iron casing and ductile-iron suction cover for sand-carrying water.
- Double inside mechanical seals: silicon carbide (SiC) faces running in an oil chamber, further protected by a lip seal on a replaceable stainless steel shaft sleeve, with Tsurumi's Oil Lifter.
- Built-in thermal and amperage-sensing protector: guards the motor against overload.
- Anti-wicking cable entry: limits water creeping along the cable cores into the motor if the cable sheath is damaged.
- Continuous-duty motor: air-filled, copper-wound induction motor with double-shielded, permanently lubricated C3 ball bearings.
- Single-phase supply: no three-phase power needed.
Applications
- Construction sites: excavation dewatering and temporary site drainage
- Rain water and ground water: removal of standing water and seepage, including sand-carrying water
- Effluent transfer: listed by Tsurumi America; with only 8.5 mm solids passage it is not suited to raw sewage containing fibrous solids
- Raw water supply: drawing raw water from rivers or lakes
- Rental fleets: Tsurumi America positions the NK series for rental and construction dewatering
Performance
The maximum head of about 18 m is the head at near-zero flow, and the maximum capacity of about 800 L/min (0.80 m³/min, about 48 m³/h) 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, so select the pump from the curve using your site's total head. These figures are read from Tsurumi America's 60 Hz performance curve; Tsurumi publishes no 50 Hz data for this model.
Technical specifications
TSURUMI NK3-22L technical specifications (Tsurumi America 60 Hz data)
| Item | Specification |
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| General |
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| Model | NK3-22L |
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| Series | NK (portable dewatering pump) |
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| Market version | Tsurumi America 60 Hz model |
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| Discharge bore | 80 mm (3 in) |
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| Discharge connection | 3 in NPT straight male connection (cast iron) |
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| Hydraulic performance (60 Hz) |
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| Max. head (at zero flow) | approx. 18 m |
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| Max. capacity (curve end point) | approx. 800 L/min (0.80 m³/min, approx. 48 m³/h) |
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| Solids passage | 8.5 mm |
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| Impeller type | Semi-vortex |
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| Electrical |
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| Motor output | 2.2 kW (3 HP) |
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| Motor | Single-phase 2-pole air-filled induction motor, continuous duty, insulation class B |
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| Speed | 3,465 rpm (60 Hz) |
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| Power supply | Single-phase (voltage and frequency as per nameplate) |
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| Starting method | Capacitor start |
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| Motor protection | Built-in thermal and amperage-sensing protector |
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| Cable | 10 m (32 ft), chloroprene sheath |
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| Seals and bearings |
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| Shaft seal | Double inside mechanical seals, silicon carbide (SiC) faces, oil-lubricated, with Oil Lifter |
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| Oil seal | NBR lip seal on a replaceable stainless steel shaft sleeve |
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| Lubricant | Turbine oil ISO VG32 |
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| Bearings | Double-shielded C3 ball bearings (upper 6204ZZC3 / lower 6305ZZC3) |
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| Materials |
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| Impeller | High-chrome cast iron (ASTM A532 Class III Type A) |
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| Pump casing | Cast iron (ASTM A48M Class 30B) |
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| Suction cover | Ductile cast iron (ASTM A536 65-45-12) |
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| Suction strainer | Cold-rolled steel |
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| Shaft | 420 stainless steel |
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| Motor housing | Aluminium alloy |
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| Exposed fasteners | 304 stainless steel |
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| Liquid limits |
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| Liquid | Rain water, ground water, sand-carrying water |
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| Liquid temperature | 0–40 °C |
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| Dimensions and weight |
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| Dry weight (excl. cable) | 33.0 kg |
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| Overall height | 669 mm |
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| Min. water level for continuous running (C.W.L.) | 120 mm |
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Sources: Tsurumi America NK3-22L data sheet, performance curve, dimension drawing and sectional view (60 Hz), and the Tsurumi KTV/KTVE/NK operation manual (B-10276). Rated current depends on the supply voltage; refer to the nameplate.
NK series comparison
Tsurumi NK series model comparison (60 Hz data)
| Model | Power | Max. head | Max. capacity | Casing / impeller |
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| NK2-15 | 1.5 kW | approx. 21 m | approx. 420 L/min | Rubber / ductile iron |
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| NK3-15 | 1.5 kW | 21 m | 420 L/min | Synthetic rubber / ductile iron |
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| NK4-22 | 2.2 kW | 26 m | 495 L/min | Synthetic rubber / ductile iron |
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| NK3-22L (this product) | 2.2 kW | approx. 18 m | approx. 800 L/min | Cast iron / high-chrome iron |
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Optional accessories
- 3 in × 50 ft NPT discharge hose (Tsurumi America genuine accessory)
- 220 V float switch for pumps up to 3 HP (max. 15 A full-load current) (Tsurumi America genuine accessory)
The NK series has no built-in automatic operation; add a float switch for level-controlled start and stop. Please contact us about accessory availability.
Safety and installation
- Electrical connection must be made by a registered electrical worker in line with local regulations, with a dedicated earth-leakage circuit breaker, a thermal overload relay and a secure earth. Never earth to gas or water pipes, lightning rods or telephone earths.
- Keep the supply voltage within ±5% of the nameplate rating. On a generator, do not run other equipment from the same generator.
- Do not run the pump dry, below the continuous running water level (120 mm), or against a closed gate valve.
- Lift and carry the pump by its handle, never by the cable, and do not start it while it is suspended.
- Secure the discharge hose so it cannot whip. If the pump could sink into sediment, stand it on a firm base such as a concrete block.
- The pump is neither dust-proof nor explosion-proof. Do not use it where toxic, corrosive or explosive gas may be present.
- Do not pump oil, seawater or salt water, chemicals, corrosive liquids, organic solvents, flammable or explosive liquids, or liquids above 40 °C. Not for potable water.
- Never run the pump while anyone is in the pool or sump. The surface can be hot during and after operation.
- The pump restarts automatically when power returns after an outage. Isolate the power before maintenance, after a power failure and during long idle periods.
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.
- Daily: check that running current is at or below the rated value and voltage is within ±5%.
- Monthly: measure insulation resistance; it should be at least 1 MΩ (at least 20 MΩ when new).
- Check the oil every 6 months or 3,000 hours; change it every 12 months or 6,000 hours with VG32 turbine oil.
- Mechanical seal replacement should be done by a dealer or Tsurumi service centre. An overhaul is recommended every 2 to 5 years.
- Pumps left standing in water should be run at least once a week to prevent seizing.
