When using a submersible water pump, it is important to learn some common issues that can arise. Submersible pump use in municipal systems is not new. The benefits of submersible pumps are well known. Since the pumps are placed into the earth, in a stable environment, they are usually immune to the environmental and weather factors that cause hollow shaft motors and drive conventional LSTs.

These pumps and motors eliminate the bearing systems and drive shaft of LSTs, hence reducing the required maintenance and mechanical complexity. Oil doesn’t drip into the well for bearing lubrication. Water wells can be located adjacent to the housing areas. Submersible pumps also don’t require structures in order to enclose them and don’t produce any surface noise.

Common submersible pump issues

Standard well types of submersible pumps are water-filled and rely on water to lubricate the internal of the motor. These pumps are reliable when applied within their limits of hydraulic loading, temperature and power requirements. Typical domestic, agriculture and municipal systems are excellent applications for submersible pumps. Unfortunately, the motors are used in applications that exceed the design criteria of the pumps. As a result, these pumps can fail and the benefits that come with them can be lost and forgotten.

How to protect submersible pumps

There are some common causes of submersible pump problems and these failures include hydraulic loading, overheating, voltage supply, voltage spikes and motor seals. We will discuss some of these issues before you decide to buy submersible water pump.

Overheating and failures

Over-temperature is a common problem that affects motors. Over-temperature is caused by overloading the motor, pumping hot water, loss of cooling flow past the ochre, motor or scale buildup and starting and stopping the motor frequently. Submersible motors should cool themselves.

This is typically accomplished almost everywhere by transferring the internally generated heat of the motor to the water flowing past the pump’s motor into the submersible pump. A lot of standard water well pumps are designed to do this and add some safety margin.

The thrust bearing of the pump supports the thrusting weight of the water column that the pump lifts. In standard motors, the thrust bearing is lubricated by water. A very small film of the water between the elements of thrust bearing offers lubrication between 2 bearing surfaces. If the motor overheats, this water film can approach the boiling point and if it boils then the lubricating film will be lost.

Hydraulic loading

Another problem with submersible pumps in municipal applications is the water hammer or the hydraulic shock loading. A water hammer occurs when a column of water moving rapidly encounters an obstacle and changes velocity suddenly. Using multiple pumps on a common supply manifold is a popular cause of a water hammer.

When a submersible water pump turns on or off, the water hammer is generated. When any kind of valving is actuated then the water hammer can occur. It is therefore important to install check valves in the discharge string to reduce water hammer.