Tsurumi GPN Slurry Pump — Submersible Agitator Pump for Sand and Sludge

A submersible slurry pump with a built-in agitator for lifting settled sludge, clay and sand — from farm ponds and irrigation canals to shallow river reaches. Dynamach is an authorised Tsurumi distributor in Thailand.

Why an ordinary submersible pump fails on sludge

Irrigation canals, farm reservoirs and fish or shrimp ponds lose depth every season as clay, silt and sand settle on the bottom. Put a standard drainage pump in and two things usually happen: it lifts the clear water above the sediment and leaves the sludge where it was, and an impeller that was never designed for sand wears out long before it should.

The GPN series is built specifically around those two problems.

Agitator

A high-chrome cast iron agitator sits on the same shaft as the impeller and turns with it. It stirs the settled sludge around the suction inlet back into suspension, so thick slurry — not just the clear water on top — is drawn up with the flow.

High-chrome cast iron on every sand-contact part

The impeller, suction plate and agitator take the heaviest abrasion. Tsurumi makes all three in high-chrome cast iron, so the pump can work in sand-laden ponds without frequent impeller replacement.

Adjustable suction plate

As the clearance between impeller and suction plate opens up with wear, it can be reset to restore the original performance (GPN422, GPN622 and GPN837).

Motor cooling jacket

The pumped liquid circulates around the motor, so the pump keeps running for extended periods even when the water level drops below the motor housing. It is not a dry-running pump: models from 22 kW upward carry a sensor that cuts power on dry running.

Desilting work the GPN is used for

• Irrigation canals and field ditches — remove built-up sludge that restricts flow and restore channel depth without waiting for an excavator to reach the site
• Farm reservoirs — recover storage volume lost to sedimentation before the dry season
• Fish and shrimp ponds — pump out bottom sludge between production cycles without draining the whole pond
• Orchard drains and narrow channels — the pump is lowered in and works under water where large machinery cannot go
• Re-use of dredged material — pump sludge directly to embankments, raised beds or soil improvement instead of trucking it away
• Contract desilting — farmer groups, cooperatives and local contractors run one unit across a whole season of jobs

Before you decide: the GPN is a three-phase motor pump. It cannot run on a single-phase domestic supply; the site needs a three-phase connection or a generator of sufficient capacity. Dry weight starts at 160 kg, so lifting equipment is required to lower the pump into the pond. If you are unsure whether your site is ready, ask us first — there is no charge.

River dredging — the same pump at basin scale

Thailand's main rivers silt up each year with soil, clay and sand carried down from upstream, reducing the channel's capacity. When the flood season coincides with high tides, low-lying land along the river floods repeatedly and riverside farmland is affected over a wide area.

Conventional dredging — large dredgers, or excavators working from the bank — runs into fuel cost, noise and exhaust, difficulty reaching isolated shallow spots, and sediment plumes that disturb the ecosystem while work is under way.

The approach we propose is to mount GPN pumps on an electrically driven barge or dredging boat and pump sediment directly from the shallow reach, for five technical reasons:

• Agitator — re-suspends compacted sediment so concentrated slurry can be pumped; suited to riverbed clay and mud
• High-chrome cast iron parts — resist abrasion from sand, gravel and debris on the riverbed, reducing maintenance frequency
• Cooling jacket — sustains long continuous runs even at low water, as spot dredging requires
• Electric drive — pairs with an electric boat or barge, cutting exhaust and noise compared with diesel plant
• Access — fits on a small vessel, moves easily between spots and does not require closing the waterway to traffic

Dredged sediment is a resource, not waste

Riverbed soil and mud can be put to use: improving riverside farmland, filling public land and retention basins, reinforcing flood embankments, as raw material for bricks and blocks, and restoring eroded mangrove and coastal areas. Planning the end use from the start substantially reduces a project's disposal cost.

In every case the sediment must first be tested against the Pollution Control Department's soil quality standards, particularly for heavy metals such as arsenic, cadmium and lead.

Industrial and construction duties from the catalogue

Beyond desilting, Tsurumi's GPN catalogue lists these applications:

• Pile driving — pumping the slurry produced by piling
• Foundation work — removing cement water and sandy water from foundation pits
• Mines and quarries — pumping stone and ore washing water
• Wastewater treatment plants — removing sludge from settling basins
• Steel plants — pumping scale out of the system

Specifications — all six GPN models

All figures are taken from the Tsurumi catalogue. Use them for a first pass, but select the model on the flow and head required at your site, not on motor rating alone.

Inch sizes are nominal equivalents of the millimetre bore. CTP = thermal protector that cuts the circuit on motor over-temperature (15 kW and below). MTP = thermal protector that cuts power on over-temperature or dry running, paired with an electrode that detects water leaking into the oil chamber (22 kW and above). Adjustable suction plate on GPN422 / GPN622 / GPN837 only. Dry weight excludes cable. D.O.L. models can be ordered with Star-Delta starting. The manufacturer reserves the right to change specifications without notice.

Download the GPN catalogue (PDF, 1 MB) — it contains the flow and head curves for all six models at 50 Hz and 60 Hz, overall dimensions, and details not reproduced on this page.

Materials

• Impeller — semi-open, high-chrome cast iron
• Suction plate and agitator — high-chrome cast iron
• Suction cover and pump casing — grey cast iron
• Shaft seal — double mechanical seal, silicon carbide faces
• Shaft sleeve — 403 stainless steel
• Shaft — SCM435 (JIS) chrome-molybdenum steel, tensile strength not less than 930 N/mm²
• Motor — dry-type induction motor, continuous rating, class F insulation, ISO VG32 turbine oil
• Discharge connection — hose coupling (all models)

The material set is the same across all six models.

What to confirm before ordering

1. Volume of sludge to be removed, and the distance and height it must be pumped — read the required duty point against the curves in the catalogue
2. Three-phase supply at the site, or a generator sized for the motor
3. Lifting equipment for the pump's dry weight
4. Electrical frequency — Thailand runs at 50 Hz, so use the 50 Hz curves
5. Whether a spare impeller and seal kit should be held on site for sandy duty

Frequently asked questions

How is the GPN different from a standard submersible pump?

Site crews often call any submersible a "diver pump", but a standard unit only handles water with dilute sediment, and its impeller wears quickly in sand. The GPN differs in having an agitator and high-chrome cast iron wear parts.

Which model should I choose?

Decide on the volume of sludge and the distance it has to be pumped, not on motor rating alone. A small pond with a short discharge run needs only the small model; move up when the sludge has to travel far or the pump runs all day. Discharge bores run from 80 mm (3 in) to 200 mm (8 in), and solids passage is 30 mm (46 mm on the GPN837). Send us the pond size and sludge depth and our engineers will size it free of charge.

Can it run on a single-phase supply?

No. Every model uses a three-phase motor of 5.5–37 kW, so the site needs three-phase power or a generator of sufficient capacity. If only a two-wire domestic supply is available, this series will not work — call us, as other pump series are available. The GPN837 starts Star-Delta; the other models are D.O.L. but can be ordered as Star-Delta.

Why buy through Dynamach?

Dynamach is an authorised Tsurumi distributor. Our engineers check the specification before you buy, support the installation afterwards, and supply genuine spare parts.

Related pages

• Tsurumi submersible pump range
• Franklin Electric borehole pumps
• Request a quotation or an engineering review