How Submersible Pumps Work: Advantages and Disadvantages of Submersible Pumps
A submersible pump, also called an electric submersible pump, is a pump that can be fully submerged in water. The motor is hermetically sealed and close-coupled to the body of the pump.
A submersible pump pushes water to the surface by converting rotary energy into kinetic energy into pressure energy. This is done by the water being pulled into the pump: first in the intake, where the rotation of the impeller pushes the water through the diffuser. From there, it goes to the surface.
The major advantage to a submersible pump is that it never has to be primed, because it is already submerged in the fluid. Submersible pumps are also very efficient because they don’t really have to spend a lot of energy moving water into the pump. Water pressure pushes the water into a submersible pump, thus “saving” a lot of the pump’s energy.
Also, while the pumps themselves aren’t versatile, the selection certainly is. Some submersible pumps can easily handle solids, while some are better for liquids only. Submersible pumps are quiet, because they are under water, and cavitation is never an issue, because there is no “spike” in pressure as the water flows through the pump.
There are a few disadvantages with submersible pumps, and two have to do with the seal. The seals can become corroded with time. When that happens, water seeps into the motor, rendering it useless until it is repaired. Also, that seal makes the submersible pump a bit difficult to get into for repairs.
The other main disadvantage is that one pump does not fit all uses. Single stage pumps are used for most home and light industrial pumping. This includes aquarium filters, sewage pumping, or sump pumps for drainage. Multiple stage pumps are used for anything underground, such as water wells or oil wells. Also, pumps are made to work with thin liquids like water, or thick ones like sewage.