As the name suggests, a submersible pump is designed to work with the entire assembly, consisting of pump and motor, fully submerged in the liquid or medium to be processed. This type of pump has a hermetically sealed motor which is close-coupled to the pump body. The water-tight enclosure around the motor is usually filled with oil to protect it from damage by preventing the entry of any liquid which may cause a short circuit. When a pump is submerged there is positive fluid pressure at the inlet of the pump. This condition can create greater efficiency due to less energy required to move the fluid through the liquid path of the pump A submersible pump operates by pushing, as opposed to drawing, liquid during the pumping process. This is extremely efficient because the pump uses the head of liquid in which it is submerged to operate and no energy is spent in drawing the liquid into the pump. A positive effect from the pump being submerged is that the motor is cooled by the liquid around it, preventing overheating.
