What is a Submersible Pump

What Is A Submersible Pump:

A Submersible Pump is a type of a pump which is contained in an air tight sealed motor which is close to the pump body. To use this pump, the entire assembly is submerged into the fluid which is to be pumped.

A Submersible Well Pump does not rely on the external pressure of air to lift the fluid. Rather, mechanical seals are used to ensure that the fluid does not enter the body of the motor and cause a short circuit in the motor. Thus, these pumps can provide a significant amount of lifting force.

The pump is often connected to a pipe or a flexible hose pipe or it is lowered down guard rails or wires. The pipe is then rested on a coupling (called a 'duck's foot coupling') and is connected to the pipe network for delivery.

Applications Of Submersible Pump:

Submersible pumps have found their uses and applications in places where any fluid needs to be drained or pumped out. Examples are:

• Drainage
• Sewage pumping
• Slurry pumping
• Aquarium filters
• General industrial pumping
• Pumping water from bore wells
• Pumping oil from oil wells

Electric Submersible Pumps

The last example from the list given above is perhaps the most important and well-known application of submersible well pumps. The specialized pumps are known as Electric Submersible Pumps.

In an electric submersible pump, there are several parts which rotate a series of centrifugal pumps which increase the pressure of the oil in the well and cause it to be pushed to the surface.

These electrical submersible pumps use a high voltage AC power source which varies from 3 to 5 kilo volts. This drives a motor that is capable of running at high temperatures (up to 300 degrees Celsius or 150 degrees Fahrenheit) and at high pressures. This motor can pump liquids from deep wells (as much as 12000 feet or 3.7 kilometers) with really high amounts of energy which can go up to 1000 horse power. Their rotational speed is also quite high and can go up to 4000 rotations per minute.

However, these motors are not very tolerant of solids such as sand, which can often be found mixed with liquids at such depths. Electrical submersible pumps therefore have a low amount of efficiency.

Despite these obvious flaws, these pumps have become quite popular. One of the uses to which these electric pumps are put to is best seen when naval vessels use these pumps to dewater contaminated water from flooded areas.

These electric submersible pumps use a 440 volt AC power source which operates a centrifugal pump. This kind of pump can also be used out of the water. It uses its suction power to suck in the liquids. Normally, the pumped liquid is then circulated around the motor in a tube so as to cool down the motor, as it tends to get heated up. But this can often lead to the liquid leaking into the motor from the tube. That is why certain types of fluids are avoided to be used for such purposes.

Maintenance of Submersible Pumps:

The maintenance of submersible pumps is quite difficult. Usually, there are seals which prevent the fluids from getting inside the motor to cause a short circuit. However, care must be taken with the kind of fluid that is being pumped. Different fluids react differently.

Hot water and flammable liquids must be handled quite carefully. The hot water can easily damage the parts of the motor due to its heat, while flammable liquids can easily catch fire and cause a lot of damage to the internal parts of the pump.

When the liquids pumped out are both hot and flammable, the electric supply used to run the motor may often heat the fluids and cause the motor to burn or explode.

Thus, special parts are used to drain such fluids. This leads to heavy maintenance costs for submersible pumps.

Also the motor often lies completely submerged under the fluid that is being pumped out. So, damage can be easily caused to the motor and the outer parts. This also adds to the maintenance costs for submergible pumps.