For clear water applications, the submersible pumps can be used for either bore well or open-well applications. Bore well submersibles are used to pump water starting from 50 feet below the ground. At present, these pumps are being used for depths up to 1500 feet below the ground. However, as the ground water levels are rapidly decreasing, there are efforts to design the submersible pumps for higher depths. The size of the bore well can be 3”, 4”,5”,6”,7”, 8”. Submersible pumps are typically used for residential apartments, commercial complexes, and municipal and industrial water circulation, irrigation systems.
The choice of a submersible pump depends on the application. Before buying a pump, ensure that the specifications of the pump suit the requirement. Some of the key requirements that need to be considered while selecting a bore well submersible pump are listed below:
● Size of bore well
● Yield of bore well
● Static water level (below ground level)
● Dynamic water level (below ground level)
● Expected maximum low water level during summer
● Proposed erection depth of the pump set
● Existing /proposed delivery pipe size
● Vertical elevation from water source to discharge point
● Horizontal distance from bore well to delivery point of the application
● Number of fittings like tees, bends, valves etc.
Key terms to understand specifications/ requirements
Head – the total head is calculated as below:
Total Head = Suction Head + Delivery Head + Friction Loss + Fitting Losses
Suction Head – Distance between water surface to pump suction point. Can be considered as zero for a borewell submersible pump
Delivery Head * – Distance between pump to delivery point of the application
Friction Loss * – Loss of head due to fluid (water) flow through the pipe.
Fitting Loss – Loss of head due fittings, like gate valve, check valve, bends etc.
* While calculating the delivery head and friction losses, consider the length of both vertical and horizontal pipe until the delivery point.
Diameter of the bore well is very important to select the right size of pump
Delivery pipe size
Delivery pipe size is the diameter of the pipe at pump outlet
It is measured in inches or millimeters
If there is an existing pipeline, the delivery casing of the pump should match the existing pipe size
If it is a new pipeline, the delivery size will be decided depending on the distance to which the water must be delivered
Material of construction
Material of construction should be chosen based on the application of the pump
Material of construction is important for the reliability of the pump
The required amount of water at the outlet is called discharge. The discharge is usually around 80% of the total yield of a bore well submersible pump. So, please choose the right kind of pump after evaluating the discharge required.
You can find how to connect the submersible pump to a power source in the instruction manual. However, it is recommended to be done by a trained mechanic. The end user is not recommended to rewind the motor on his own. It has to be done through a trained mechanic or at authorized service centers.
Air lock is when a submersible pump has air trapped in the head even though the water level is well above the top of the pump. This occurs when a check valve is used without a relief hole in the discharge pipe. (NOTE: A check valve is always recommended to prevent backflow into the basin.) The pump can turn on but can’t pump water due to air in the pump head.
It could be several factors behind this:
● Not enough water. Check to ensure that there is enough water present in the tank to allow safe pumping; the Mega Digital Spray Control System shuts the water pump once a sufficiently low water level has been reached.
● Air lock. If there is too little water in the tank, the pump may have drawn in a large air pocket that is preventing the flow of water.
The lift displacement is too great? If you are operating a suction lift pump, be sure that the water reservoir you are drawing from is no more than 7 feet below the pump, otherwise the resistance to flow may be too great.
● The pipes that are too small or have too many elbows. Pumping water through small diameter pipes (and pipes with elbows and check valves) increases the water pressure, but as a result also increases flow resistance. If the resistance is too great, your pump will not perform.
The following reasons could be why the 4” submersible pump will not start:
1. There is no voltage at the power.
2. There is no voltage at the pressure switch, replace faulty pressure switch.
3. There is no voltage at the control box, rewire the supply to the control box.
4. Cable or splices are bad, check all wires to ensure there are no knicks, your splices are well connected and/or consult a licensed electrician or serviceman
The control box is wired incorrectly, reconnect the control box correctly (see wiring diagram in manual)
If your submersible pump is not fully submerged the unit will run dry, this will lead to the unit getting very hot and overheating. To prevent this, simply ensure that you submerge the unit fully in water. And the overheating may result from another underlying condition which causes other issues alongside raising a pump’s temperature. The fluctuations in pump’s temperature may even from：
● Incorrect installation
● Foreign material deposition outside the motor
● High/low voltages
● Rise in temperature of ambient water
If you notice your pump getting extremely hot, unplug the unit and submerge it in very cold water for 20-30 minutes. This is plenty of time for the pump to cool off. When you place the pump back in the pond water, plug it in and it should work just fine.