• September 20, 2018
  • Tim Wolstencroft
  • Blog

The ultimate goal is to achieve sufficient and efficient irrigation of the crops. The priority is to provide enough water to the crops and distribute the water evenly so everyone’s getting a fair share.

Another priority is to achieve that proper irrigation by using minimal resources. Water usage should be minimised while still allowing the plants to receive enough water. Too much water might be wasted due to wind during the sprinkler action. Or, too much water might carry away (agricultural runoff) essential nutrients for plant growth. And yes, high water usage is a huge financial waste especially in large farmlands.

In line with these priorities, farmers now pay special attention to selecting an irrigation pump for agricultural use. This is a crucial decision because it can affect your crop yield and running costs.

A guide on choosing an irrigation pump for agricultural use

Although there are varying requirements, here are the most common considerations in choosing an irrigation pump for agricultural use:

  • Requirements about discharge and pressure
  • Upfront costs (might include depreciation, interest)
  • Durability (should withstand frequent use and exposure to environmental elements)

The discharge and pressure requirements affect the amount of water and how uniform it is distributed. Uneven plant growth (some crops grow taller than the others) might be because of lack of water to some areas. But as mentioned earlier, too much water can carry away nutrients. In addition, high water usage accelerates soil erosion.

Another consideration is about the upfront cost. Is it practical to invest in a new pumping system? Will we get significant ROI from the new pump? Almost anything can be achieved (e.g. sufficient crop irrigation) if we just throw money at it. But it’s not the engineering way and you can instead invest your money on something else (like a more efficient and less damaging transport of your harvest).

Aside from the basic requirements (pressure and discharge) and upfront cost, of course farmers also consider the durability of the pumping system. It’s especially the case in agricultural settings wherein pumps encounter regular wear and tear.

Both the physical and chemical actions can accelerate abrasion and corrosion on the pump’s internal pumps. For example, physical abrasion and chemical corrosion can reduce the impeller diameter. This results to lower performance of the pump. This is especially the case in centrifugal pumps wherein water pressure and flow rate depend both on the impeller’s speed and size. Abrasion and corrosion also introduce an early need for repair or replacement.

Aside from abrasion and corrosion, cavitation is also a threat to the performance and integrity of the pump. This is also the result of wear and tear wherein cavities form. These empty spaces might be the introductory sites for corrosion and further abrasion. These can also be houses for dirt and other small solid objects.

Those are the general considerations. Let’s now go deeper and discuss further how to choose a pump for agricultural applications:

Important notes on pump types

There are various pumping systems and they have different specialised advantages and functions. Let’s explore them now.

Earlier we mentioned corrosion and its effect on pump performance. Well, this can be prevented or slowed down with the use of a centrifugal pump. In this pump system corrosion is less because it’s installed above the water surface. Take note that corrosion requires a substrate (the metal of the pump), water and oxygen. Any absence or lack in any of these prevents or slows down corrosion rates.

Other advantages of centrifugal pumps include:

  • Easy and cheap to install
  • Low-cost maintenance
  • Can be mounted on skids

Both upfront and in the long run, many farmers find value in the use of centrifugal pumps. In fact, centrifugal pumps are widely used due to their advantages and simplicity.

On the other hand, positive displacement pumps are not that widely used. These operate in a low volume way. Because of the low volume, these pumps are used for drip, irrigation and mist applications. Good thing about positive displacement pumps is they can maintain a constant flow rate regardless of the pressure (which is why these pumps are also called constant flow systems). As a result, they’re good at handling high viscosity applications.

Remember that performance of centrifugal pumps depend on the impeller’s speed and size. If the viscosity or the “heaviness” of the water is a bit higher, the impeller might slow down or struggle to facilitate water movement.

In agricultural settings the water’s viscosity is approximately normal, which is why centrifugal pumps are still good for these applications. Positive displacement pumps can be used for other applications that require constant flow rate while transporting higher viscosity liquids.

By now you might have already heard about variable speed pumps. Although these are more costly upfront, they can provide long-term savings on running costs. That’s because the pumps can be set to operate at the exact speed required to achieve the desired pump duty (flow and pressure requirements).

Also, there’s a wide range of irrigation demands and one-size-fits-all is not true anymore. Pumps with fixed speed motors still provide functionality. But for maximum cost savings given that performance criteria are being met, customisation (and the freedom to adjust) is recommended.

In addition, variable speed control can reduce the effect of pressure surges. These surges are the result of the sudden stop or directional shift in the flow of water. The sudden pressure increase could cause noise and vibration in the pipeline. Worst, pipe collapse may occur because of the surge.

How to choose the right pump

There are several variables at play here. But ultimately, the goal is to achieve sufficient and efficient irrigation of the pumps. Crop yields can increase significantly if every square metre of the land roughly receives the same amount of water. Also, operating costs would be minimised while still achieving the optimal harvest outcome.

Irrigation designers and pump specialists work hand in hand to create a customised solution based on the farm’s requirements. You also have to bring your expertise to the table because of your knowledge about the plant species, crop’s growth stages and root structure and soil composition. The combination of technical expertise often results to the optimal outcome.

To start, consider centrifugal pumps with variable speed motors. These are widely used in many irrigation applications. Also, the simple design of centrifugal pump plus its use (installed above water surface) is ideal for irrigation. You’ll worry less about the corrosion because the pump won’t be submerged in water.

Pump specialists can provide you with an excellent system so you can get the most out of the centrifugal pump. Their engineers can even create a multi-pump package or design a complete system according to your specific requirements. This way, your pump will be perfect for your irrigation demands. Take note that your farm has a different terrain, land area and crops. You also have to consider the weather patterns in your area (sunlight, wind, rain). All these variables are often considered to select or design the optimal pump system for your application.

Here at Tru-Flo pumps we can select and design the optimal pump system for your irrigation requirements. First, we will study your requirements and the site so we can come up with a customised solution for you. This way, we can optimise the pump’s usability while minimising the running costs.

We develop and engineer pumping solutions for small, medium and large-scale projects. These have different requirements and business objectives. As a result, each of these projects require a tailored solution.

Contact us today and let’s discuss your requirements and application. We have already sold and serviced over 21,245 pumps. We will bring our expertise and integrate it with yours so we can come up with an optimal solution together.