Do you ever feel overwhelmed by all of the sprinkler options available? If so, never fear – the Valley® Water Application team is here! These are our top 5 “life hacks” for effective sprinkler package design. When all these options are utilized at their full potential, they allow you to fully harness all the advantages of mechanized sprinkler irrigation across a broad range of soils, topography, crops and climates, resulting in higher yields and profits.
1. Know how to determine machine flow rate.
Figure 1. Area (ac.) to be used for flow rate calculation - figure with end guns running and/or corner extend entire rotation.
One of the first things that a sprinkler package designer must identify is what the overall flow rate of the machine should be. Ideally, we want to be able to to meet the peak evapotranspiration (ET) rate of the highest water use crop that we plan to grow. With experience, a dealer will often become familiar with a GPM/acre capacity that works well in their particular climate. At that point, they multiply the GPM/acre times the number of acres to be irrigated to arrive at the ideal flow rate (Figure 1). While this method will work well in most typical situations, be sure to keep an eye out for factors that may warrant higher or lower flow rates.
2. Know the soil.
Have you ever wondered why there are so many sprinkler options? One of the main reasons is differences in soil characteristics, which require different water patterns and droplet sizes. Preventing ponding and runoff is a key driver behind high-performance sprinklers. In general, this means using sprinklers that have a large water pattern and a droplet size that is gentle on the soil surface, yet resists evaporation and wind drift. High performance sprinklers are able to do all these factors well, and subtle changes to the deflector pad, sprinkler operating pressure, and spacing allow the designer to fine-tune a sprinkler package to the field.
3. Know about pressure.
Inevitably, when dealing with irrigation, the topic of pressure comes up. Pressure is important! Pressure is essentially the energy that pushes water throughout the irrigation machine. If the pressure delivered to the center pivot or linear is different than what the machine was designed for, there is a potential for water application issues. Understanding the aspects of pressure is essential to be able to make reasonable decisions regarding water delivery for any type of irrigation.
If the desired end pressure is achieved, most likely all sprinklers on the machine will have adequate pressure (Figure 2). Systems without pressure regulators should be operated at the end pressure stated on the sprinkler chart.
Figure 2. Pivot pressure versus end pressure as a result of friction loss and elevation. Maintaining the desired end pressure ensures all sprinklers inwards have enough pressure.
Field elevation above the pivot point or linear cart is often referred to as “up elevation.” For every 2.31 feet of up elevation, the pivot inlet pressure requirement is increased by 1 PSI on pressure-regulated machines to be able overcome this elevation. Unregulated machines can’t compensate for elevation, so water distribution worsens as more elevation is introduced.
4. Know about spacing.
Sprinkler spacing most notably has an effect on the how the water patterns from adjacent sprinklers overlap, which is a key consideration for uniform water application. Sprinkler spacing may change along the length of the machine to meet the designer’s water application and economic goals. Sprinkler spacing that is too wide can reduce uniformity, while outlet spacing that is excessively close can have diminishing returns for the added cost of more sprinklers.
5. Know about nozzle sizing.
Figure 3. Sprinkler required flow is a function of the area underneath it and the overall flow/area of the machine.
Designers need to understand many factors that go into determining sprinkler flow requirements and how to influence those factors to yield certain results. Figure 3 shows the imaginary rings created half way between each sprinkler. The area of these rings become the basis for determining a sprinkler’s flow requirements, and therefore the nozzle which will be selected.
Knowing these 5 important things is a great start to designing the optimal sprinkler package. Please reach out to your dedicated Valley dealer with any questions.
Want to learn more about how you can keep your sprinklers in top shape this growing season? Download our free eBook today!