A submersible pump is a mechanical equipment that works by pushing the water toward the surface instead of pulling it. It has a hermetically sealed motor connected to the pump body that helps to push the fluid toward the surface. It is a most famous type of the centrifugal pump. A submersible pump mainly uses to pump the water from the wells. This type of pump pushes water toward the surface by changing the rotatory motion (speed) into kinetic energy, and diffuser blades further convert this K.E into pressure energy.
The significant benefit of this pump is that it can prevent the pump from cavitation - these pumps are known as submersible pumps because these submerge entirely in the water. Therefore, the principal purpose of these pumps is to pump water out of the tanks, wells, or other vessels by submerging into the water or other fluids. These pumps also use in hot water-heavy oil applications where pressurized liquid from the ground is used to power a hydraulic motor in wells instead of an electric motor. Typically, this pump doesn't require priming because it completely submerges in the fluid. However, this high-quality pump creates complexity and cannot function properly without problems, so it is never taken out of the water.
The working of the submersible pump is a little bit different than a jet pump. Because jet pumps transfer the fluid by pulling it while submersible pumps transfer the fluid by pushing it. A submersible water pump is a machine that is linked with a completely sealed motor. It is a type of centrifugal pump. Therefore, its working is very similar to other types of centrifugal pumps. Submersible pumps submerge entirely in the water.
During the working of the submersible water pump, it pushes the water toward the surface. As the water of well or reservoir enters into the pump by the foot valve, it strikes the impeller. An impeller is a rotatory unit that has multiple fixed blades. This impeller is connected with an electric motor through a shaft. The impeller rotates with the rotation of the shaft. As the water strikes the blades of the impeller, the blades convert the water kinetic energy into speed and increase the speed of the water. After passing through the impeller, the water enters into the diffuser, which further transforms the speed of the water into pressure energy. In this way, the diffuser increases desired pressure of the water. After that, pressurized water discharges through the outlet valve of the pump. In this way, submersible pumps push the water towards 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. Caution must be used with submersible pumps. They must be fully submerged. The water around a submersible pump actually helps to cool the motor. If it is used out of water, it can overheat.