What is an Immersible Pump?

Posted on Dec 1, 2020

Immersible Pump

Immersible pumps are largely used in municipal and industrial sectors. They are able to pump a wide variety of fluids and materials gently and with low pulsation.

About Immersible Pump

Immersible pumps are cost-effective, flood-proof pumps designed for dry environments. They are mounted in a vertical position with the motor above the fluid and the end of the pump extended below the fluid level. On one end of the immersible pumps is a float switch that turns the blower motor off to prevent water from reaching the cooling fan when immersed. The opposite end is also enclosed with a fan, and the pump is encased with frames and a layer of grease to avoid water seeping into the motor.

The design of an immersible pump allows it to be used in any location where flooding may be present, such as in basements, under-building carparks, stairwells, etc). Immersible pumps are cost-effective for various flooding situations, but if the motor is intended to be submerged in water for a prolonged period of time, a submersible pump should be used instead. Immersible pumps are often easier to use, less expensive, and easier to maintain. They can easily handle solids and liquids, allowing for a wide array of applications such as within stormwater drains.

Application of Immersible Pump

Immersible pumps are largely used in municipal and industrial sectors. They are able to pump a wide variety of fluids and materials gently and with low pulsation. The materials of immersible pumps are often carefully chosen so that they can adapt to all difficult conditions to achieve the best results with regard to performance, energy efficiency, and low life-cycle costs. Here are the main categories of the applications of immersible pumps:


Immersible pumps are ideal for wastewater collection, wastewater and sewage sludge treatment, industrial wastewater, manure, and ship wastewater.

Industrial Use

Immersible pumps are widely used in the manufacturing industry, such as paper, cellulose and chips, biomass, adhesives, paint, plastic granulates, solvents, sword and cooling lubricants, and brine.


In the aspect of construction, immersible pumps are used for dewatering and drainage, sewer rerouting, mine drainage, water intake and power, and flood protection.


Immersible pumps are also used in the food industry, mainly in fruits and vegetables, live fish, brewery, molasses, oils and pastes, and gels.

Immersible Pump vs Submersible Pump

People are often obscured by these two types of pumps, assuming that they are the same by the names. But as a matter of fact, they are not.

Submersible pumps are generally used for water and sewage pumping applications. Their compact design and dimension with integral float switches make them ideal for home use as well. However, since they have standard carbon and ceramic mechanical seals and limited material options (typically cast iron or lower grade stainless steel), submersible pumps are incapable of submerging into anything other than water, they are unsuitable for aggressive liquids.

On the other hand, immersible pumps are designed and manufactured specifically for use in aggressive and corrosive fluids. To allow this, they are generally made in a range of materials from stainless steel up to engineered plastics, such as polypropylene and PVDF. Since the motor of an immersible pump is above the liquid level, it can be supplied in a specialized environment. Column lengths up to six meters can be supplied and even with shorter lengths, provided that the impeller is flooded at startup the pump can still pump down to six meters.

:: Read More: The Surprising Things about Submersible Pumps

Benefits and Features of Immersible Pumps

The benefits and features of immersible pumps are shown inline below:

Ease of Maintenance

The motor of immersible pumps is easily removable and can be sent to the service shop for repair, maintenance, or replacement. Also, almost any service shop can service the immersible motor whereas shops would have to be certified to provide service to submersible motors.

Lower Initial Cost

Immersible pumps are less costly initially because their installation does not require level controls and monitors, clean water, recirculating pump, or the piping required with other types of dry pit submersible pumps.

Lower Operating Cost

Most immersible pumps have inherently more efficient motors as opposed to traditional submersible motors.

No Cooling Jackets

Immersible pumps have no jackets that may clog and require periodic maintenance and inspection.

Seal Options

All standard pump sealing options are compatible with immersible pumps.

Bearing Life

Immersible pumps have an immersible bearing frame that absorbs the hydraulic loading which can result in longer motor bearing life because of lower thrust.

Immersible Bearing Frame

Immersible pumps are usually equipped with bearing frames that are highly protected against water infiltration and are capable of submergence up to 30 feet for up to two weeks.


Using immersible pumps is very safe and healthy. You do not have to worry about the risk concerns, such as the possible presence of pathogens like HIV, Hepatitis B, etc. in sewage fluid, during routine inspection and maintenance procedures. On the contrary, other types of water pumps need dedicated steam cleaning of the motor if it is, for instance, a submersible pump.


Immersible pumps are mostly retrofitted, meaning certain components are replaceable in the event of needing a replacement without having to buy a brand new pump.


Unlike submersible pumps, immersible motors are designed to be capable of only running for a limited period of time in a submerged state. But this also allows immersible pumps to operate without pump bearings and shafts in a flood situation.

In conclusion, immersible pumps are efficient, easy to maintain, and have great serviceability. They are cost-effective because they do not require level controls, monitors, recirculating pumps,s or pipping. They can be submerged though for a limited period of time. They have lower thrust due to the bearing frame, leading to a longer bearing life. Last but not least, the shaft penetrates the bottom only and is sealed using a triple-redundant sealing system.

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