Tsurumi Submersible Pump — Choosing the Right Series

Tsurumi organises its submersible pumps by the liquid they are built to handle, not by size. Start there and the model selection becomes straightforward.

Start with the liquid, not the pipe size

The most common specification error is selecting a submersible pump by discharge bore and motor rating alone. Two pumps with identical ratings can belong to entirely different families and be completely unsuitable for each other's duty.

Before looking at any model number, answer this: what is actually going through the pump?

• Clear water — rainwater, groundwater seeping into an excavation, general drainage
• Water carrying sand or grit — dredging, quarry and mine dewatering, sumps with heavy sediment
• Sewage with large solids — treatment plants, collection sumps, building sanitary systems
• Liquid containing fibre, rag or plastic — livestock farms, food and textile plants, communal collection pits

Each of those maps to a different design philosophy, and choosing across them is what causes repeated blockages and premature wear.

Matching the family to the duty

Construction site dewatering

For general dewatering, the practical decision is body material. Aluminium alloy bodies are lighter and easier to move between positions during a working day. Cast iron bodies are heavier but substantially more resistant to wear, and the impellers are specified for abrasion. If the water carries sand, choose iron — the price difference is recovered in impeller life.

High-volume transfer

Where the requirement is large volumes rather than high head, four-pole machines running at lower speed are the better fit. Slower rotation means slower wear and quieter operation, which matters when the pump runs continuously.

Sewage containing solids

Pumps intended for sewage use wide-passage impellers designed to let solids through rather than trying to grind them. The principle is to pass, not to macerate: it consumes less energy and blocks far less readily when the solids are not stringy.

Fibre, rag and plastic

Where the liquid contains material that wraps around an impeller, a cutter design is required. A hardened cutting edge shears the material before it reaches the pump chamber. These units cost more and draw more power for the same rating because cutting takes energy, so they should not be specified for plain clear-water duty.

The sealing design is what you are paying for

Submersible pumps rarely fail because the impeller wore out. They fail because water reached the motor. Tsurumi's engineering concentrates on that failure path:

• Double mechanical seal in a single oil chamber — both seal faces are silicon carbide, which resists corrosion, abrasion and heat considerably better than the materials commonly used at this position.
• Oil lifter — a mechanism that continues to carry oil to the seal faces for lubrication and cooling even after the oil level has dropped significantly, so the seal does not run dry and burn the moment the level falls.
• Anti-wicking cable entry — the cable termination is encapsulated so that water cannot travel along the copper strands into the motor if the outer sheath is damaged or the free end is submerged. This is the failure route most often overlooked.
• Built-in motor protector — trips on over-temperature, over-current and dry running.

What to confirm before ordering

1. Liquid type, and the size and nature of any solids present
2. Required flow in cubic metres per hour at the real operating point
3. Total head — vertical lift plus friction in the pipework plus any required outlet pressure
4. Running hours per day, since continuous duty demands a more robust selection
5. Electrical supply — phase, voltage and frequency. Thailand runs at 50 Hz, and a unit built for a 60 Hz market will not follow its published curve here
6. Whether the seal kit and impeller for that model are stocked in Thailand

Frequently asked questions

Can a clear-water pump handle sewage for a short period?

It will work briefly and then block. Clear-water impellers have narrow passages, solids lodge in them, and forcing the pump to run while obstructed overheats the motor. If solids are expected, specify a family designed for them from the start.

Is a cutter pump always better than a wide-passage pump?

No — they solve different problems. Cutter designs handle fibre and rag that would wrap an impeller. Wide-passage designs handle bulky, non-stringy solids more efficiently. Using a cutter where a wide-passage pump would do means paying more and consuming more energy for no benefit.

Why must a submersible pump never run dry?

It uses the surrounding liquid to carry heat away from the motor; there is no cooling fan. With no liquid, the heat has nowhere to go and damage can occur quickly. Where the level fluctuates, fit automatic level control.

Aluminium or cast iron body — does it really matter?

It matters greatly when sand is present. Cast iron resists abrasion far better and lasts considerably longer in heavy duty. Aluminium's advantage is weight, which counts when the pump is repositioned frequently. For fixed, long-running installations, choose iron.

Which spare parts should be held on site?

The seal kit and the oil in the seal chamber are the highest-value items to stock, since they wear predictably and are the most common cause of unplanned downtime. Where the liquid carries sand, hold a spare impeller as well.

How do I verify I am buying through a supported channel?

Request the full model code and a photograph of the nameplate, confirm who provides warranty service inside Thailand, and ask how many days a seal kit would take to arrive. A supplier operating in the official channel answers the last question with a number.

Related pages

• Franklin Electric borehole pumps
• GFS glass-fused-to-steel tanks
• Request a quotation or an engineering review