The correct borehole pump selection is crucial for efficient water extraction and long-term operational success. Proper pump selection ensures reliable water supply, minimizes energy consumption, and reduces maintenance costs. Understanding the importance of this decision can significantly impact the performance and longevity of your water system.
To begin with, choosing the appropriate borehole pump aligns with the specific requirements of your water source. Factors such as the depth of the borehole, water table levels, and the desired flow rate must be considered. For instance, a pump designed for shallow wells may fail in deeper applications, leading to frequent breakdowns and costly repairs. Therefore, matching the pump to the borehole conditions is vital for seamless operation.
Moreover, selecting the right pump enhances energy efficiency. Pumps that are too powerful for the borehole consume excessive energy, resulting in higher electricity bills and environmental strain. Conversely, underpowered pumps struggle to meet demand, causing wear and tear due to overworking. Consequently, an appropriately sized pump optimizes energy use, ensuring cost-effective and sustainable water extraction.
Information required to do a correct borehole pump selection.
Below is a diagram that shows the basic information to do a proper pump selection.
- A-Static water level. This is the depth of the water level before the pump is switched on for pumping
- B- Dynamic water level. Where the water level stabilizes while pumping.
- C-Vertical height difference between the surface of the borehole and the irrigation system or storage tank (F). If it is an irrigation system, the optimal pressure and the flowrate is also required.
- D- Horizontal distance from the borehole to the tank or irrigation system.
- E-Pipeline length, diameter and kind of pipe. This is needed to determine the friction loss. This loss in pressure must be added to the required pump pressure.
Example: For Dynamic Duty:
Q: Flow rate required 1800 l/h
- A: 15m
- B: 54m
- C: 15m
- E: 1.2m of friction loss ( We will do a separate post on friction loss)
- F: 25m pressure required for irrigation
So a total pressure of 110.2m
Dynamic duty required (Duty when pump is running): 1800l/h @ 110.2m
Example: For Static Duty: (When pump is switched on and before the water level drops)
Q: Flow rate required 1800 l/h
- A: 15m
- B: 15m
- C: 15m
- E: 1.8m of friction loss ( We will do a separate post on friction loss)
- F: 25m pressure required
Static duty will be 1800l/h @ 71.8m (Pressure required)
Performance Pump Curve: Picture as below
Efficiency:
Below is a pump curves that indicates the best pump efficiency in red. You want to run your pump closest to that line. Then you get the best flow and pressure ratio to the input energy. So, you get the best value for your money. Above from that, your pump and motor are running in the best hydraulic and and electrical condition. If the pump is running to much on the left or right hand side of the best efficiency, it can cause hydraulic forces on the pump and motor. These forces cause mechanical damage to the pump and electrical damage to the motor.
Dynamic Duty:
This pump curve is the closest to the efficiency line that we can find, that makes is the correct choice.
Static Duty:
This is equally important. The more the water level drops in the borehole, the more that duty point moves towards the dynamic duty. This static duty point is not in the ultimate position on the curve, because it is to much on the right. If the pump is going to run for short periods, you have to choose a pump. closer to your static duty.
Correct borehole pump selection is not easy. Between your rainfall season and your dry season your dynamic and static water level changes. In very wet and very dry seasons it happens that you actually need a other pump. You also do not hear or see the pump. Above ground pump you can hear that it is not making a normal sound and then be pro-active.
Conclusion
In conclusion, the correct borehole pump selection is pivotal for efficient, economical, and reliable water extraction. By considering the borehole’s unique characteristics, energy requirements, maintenance implications, and water quality, you can ensure a well-functioning and durable water system. Therefore, investing in the right pump is essential for sustainable water management.