What is the difference between an immersion pump and a submersible pump?

Everything you need to know about immersion pumps and submersible pumps

These pumps are designed for permanent installation in water. Immersion pumps enable water to be pumped from a borehole or well. Submersible pumps are used to drain or empty a space or pool.
Discover the operating principles of immersion and submersible pumps, their advantages and their uses.

The operating principles of immersion and submersible pumps

The operating principle of these hydraulic pumps is to supply, thanks to their electric motors, mechanical energy that is transformed into hydraulic energy to circulate water.
They are chosen when the rise is greater than 7 or 8 metres. Below this, it is better to install a surface pump, such as a manual pump.

Immersion pumps: for wells and boreholes

They are called immersion pumps because they are installed directly in the water to be pumped. They may be made of stainless steel to resist corrosive or polluted water.
Their electric motors are entirely watertight. When they are operating, the water enters by the bottom of the pump. Discharged at the surface, it can be used directly, but is most often sent to a booster tank. Also called a bladder tank, these tanks re-establish the water flow and pressure before use.

There are two types:

The well pump

Manual well pumps are installed when the depth does not exceed 20 m.
The flow rate of the discharged water must be adapted according to the quantity of water contained in the well. Indeed, after heavy rainfall or drought, it is not rare for the volume to vary.

The borehole pump

These are designed to recover water from a great depth.
With a much smaller hose diameter, they have a very good flow rate.

The submersible pump: a lifting pump

The main characteristic of submersible pumps is that they can be used with different types of liquids.
The choice of pump technology and accessories, including the type of seals, depends on their use.

The viscosity, density and discharge height of the water must be taken into account. To ensure the proper flow of the fluid, it is essential to consider its particle size.
Submersible pumps are fitted with floaters that automatically start and stop the device. The installation is completed by a check valve to prevent the water from falling back down and thus avoids pump damage.

What are the advantages and drawbacks of these pumps?

The particularity of immersion pumps is that they do not operate by suction but by discharge to facilitate priming. Installed at depth, they do not create a noise disturbance and are not affected by frost. Another advantage is their automatic cooling system. When the water rises, it circulates along the motor and cools it. Depending on the power of the motor or installation, it may be useful to add a cooling jacket to force the water to circulate around the motor.

By contrast, submersible pumps are a little less quiet but they have the advantage that they can be used for different types of liquids. This is a major difference with an immersion pump, which can only operate with water.

Submersible pumps thus have a wider range of applications: to discharge wastewater or water containing particles, rainwater, sewer water, construction site water, chemical treatment baths, etc.

Lastly, these pumps share the same disadvantage: they cannot operate when dry. The pumps must always be in water.

What are immersion and submersible pumps used for?

For domestic use, immersion pumps are most frequently installed to supply a household water network, for example to supply water for toilets, a washing machine or to water the garden. They are also ideal for agricultural use.

Submersible pumps, on the other hand, are used for the rapid evacuation of underground water. They are not designed to operate continuously, but rather for emergency use.
They are used to pump water from a cellar in case of flooding to avoid problems of infiltration. On a construction site, they enable rising water from the water table to be pumped out to dry a ditch.

They are also used in industry because they are suitable for many types of fluids, for example to evacuate a surface treatment bath.
Certain less powerful models are installed in ponds or fountains to ensure continuous water circulation.

Don't hesitate to contact us to discuss your project. Our experts will advise you and help you choose the most suitable model for your needs.