The past few years have been a huge source of water concern in South Africa, which can have a significant effect on agriculture and irrigation. The implementation of pumps for irrigation purposes have had a huge benefit on water availability and crop production. However, it can be difficult to know which pump is most suitable for your needs.
There are a number of pumps available for irrigation purposes including:
- Displacement pumps – displacement pumps are used to physically ‘displace’ the water to a different location. These include traditional water pumps and well pumps, as well as more modern solutions like rotary pumps or reciprocating pumps. The main way of displacing water is through the use of a piston. These are not commonly used for irrigation pumps.
- Centrifugal pumps – centrifugal pumps are those which draw water up a pipe by spinning the water using something called an impeller. The spinning of the water is known as centrifugal force, and this is the force that helps the water move upwards and against gravity towards the desired location.
- Borehole pumps – borehole pumps in South Africa are used to extract water from underground water supplies. They are thin, narrow pumps that are submersed into the water supply and then pump water above ground. They rely on a high-powered motor and a series of impellers throughout the pump that draw water up the device. They are a type of centrifugal pump.
The most common form of irrigation pumps in South Africa are centrifugal pumps, and a borehole pump is a specialized form of centrifugal pump.
What Is A Centrifugal Pump?
A centrifugal pump is any pump that uses centrifugal force to propel water to its desired location. Irrigation pumps that cover larger areas like borehole pumps, or that require more force, may have a series of impellers throughout the pump, attached to one rotating shaft. These are known as multi-stage pumps.
What Are The Different Types Of Centrifugal Pump?
At AQS Liquid Transfer, we sell a huge variety of different centrifugal irrigation pumps to meet your irrigation needs. Read on below to find out more about the different types of centrifugal pumps.
Single Stage
A single stage centrifugal pump is one impeller that rotates on a shaft within the pump casing. These are different to multi-stage irrigation pumps which have at least two or more impellers throughout the network. The pump will need to be filled with water to get started (this stage is known as priming). The liquid is then rotated with the help of the single impeller, gaining energy through centrifugal force which propels it through the casing and to the desired location.
Multi Stage
A multi stage pump is a centrifugal pump that uses a series of impellers to propel the water to a specific location The water will move at greater speed as it propels through the pump, allowing it to reach locations quicker, against greater pressures, or over greater distances. Borehole pumps are a good example of this, as they have one shaft powered by a motor that runs multiple impellers.
End Suction Centrifugal Pump
An end suction centrifugal pump is a type of pump that pushes water upwards from below the water level. As it pushes, rather than pulls water, it is much more efficient as a submersible pump as opposed to one above the water line. It is one of the most common forms of centrifugal pumps. The downside of these pumps is that if that water level dips, it becomes less and less effective. At a maximum, end suction centrifugal pumps can be placed around 4-5 meters away from the water source. If your centrifugal pump is located above or on the water line, these pumps may need to be ‘primed’ (filled with water), in order to operate efficiently.
Self-Priming Pumps
Self-priming pumps are those that do not need to be filled with water to operate. The most common form of these pumps are submersible pumps, which contain a waterproof pump and motor in one single piece of machinery. Submersible pumps solely push water upwards, and are therefore less costly to operate. They are also usually multi stage pumps as they require more impellers to push the water upwards.
A Borehole Pump
A borehole pump is a specialized centrifugal pump designed to operate in small narrow spaces to reach an underground water supply. These are therefore very thin pumps with different diameters depending on the side of the available hole. Once the diameter of the hole and depth of the water source is established, different motors are equipped to help boost the water alongside the centrifugal force.
How Can Centrifugal Pumps Be Adapted To Additional Pressure Or Flow Requirements?
Centrifugal pumps can be enhanced with a number of mechanical and electrical items to enhance their ability to handle greater pressure or flow requirements.
Examples of this include:
- A jet pump – a jet pump is a type of centrifugal pump that uses a nozzle to propel the water, creating additional propulsion.
- A turbine pump – a turbine pump is a combination of a submersible centrifugal pump attached to a motor above water. They are used for larger pump requirements like underwater aquifers, rather than smaller spaces like wells.
- A floating pump – a floating pump sits on the waterline, rather than being fixed below or above water. It is good for still waters like lakes.
Should I Use A Borehole Pump Or A Centrifugal Pump For Irrigation?
A borehole pump itself is a specialized type of centrifugal pump, but is ideal for situations where:
- The water source is extremely deep and below ground level
- The supply is difficult to reach and requires a small borehole to be drilled
- Where multi stage water propulsion is required to get water to the surface
Other types of centrifugal pumps might be more applicable for different irrigation requirements, such as:
- Submersible pumps – good for generating a water supply from a deep body of water
- Floating pumps – good for shallow bodies of water
- Self-priming pumps – useful when pumps are located below the water supply or in difficult to reach locations
- End-suction pumps – good for pushing water upwards from below the water supply
As with any pump, the success of your irrigation depends on where you are drawing your water from.
Do you still have questions? Give our AQS Liquid Transfer team a call on +27 12 548 7204 or fill out our enquiry form, our friendly team will get back to you with first-hand expertise on how to select a borehole pump for your needs.
