Working Ranch April/May 2025

to system design. While a 6-inch pipe may require less initial capital invest ment, its friction loss can increase monthly energy costs. If the flow rate of gallons per minute remains constant, a larger diameter pipe will have less fric tion loss, requiring less horsepower and energy to overcome the friction loss. Sprinkler selection depends on the desired water pattern. Keeping sprinklers approximately six feet off the ground minimizes drift and evaporation. “When a system is set to apply one inch of water, at best only about 0.90 of that water is beneficially applied, meaning it makes its way to the root zone,” Jim says. “If you have a sprin kler that’s 85% effective, divide that one inch by 0.85 and determine how much water you have to pump to ben eficially apply one inch. If your sprin kler is only 85% effective, you will waste more water, and your energy bill will be higher.” The most efficient sprinkler on the market is 91% efficient. If the pivot system does not include regulators,

Head (TDH) and the elevation and add those two together to calculate TDH. Once I know the flow rate, then I use my pump selection software to identify the most efficient option,” he explains. “Pump software helps select the proper pump, depending on the water source. Are you using a well or surface water (creek or pond)?” CORRECT COMPONENTS A suitable pump will provide the proper flow rate and pressure. It will also have a low suction head require ment. This will prevent the pump from cavitating. The suction line velocity should be kept below 3 feet per second. A small suction pipe can create whirl pools that draw in trash, like an under water vacuum cleaner. Water should gradually enter the suction tube and ease up on suction until it reaches the impeller, where velocity will increase. “The higher the pump’s efficiency, the less energy it takes to pump water to the pivot,” he says. “Each manufacturer has their own pump selection software.” Proper pipe selection is also crucial

system. While he acknowledges that cost is essential in pivot design, weighing it too heavily can result in an inefficient system that costs the producer much more in the long run. “Get prices from different compa nies, and while you stay within budget parameters, the cheapest system may not be your best option. I’m an irriga tion designer, not a salesman. I’ll tell you what you need upfront, then you decide what you buy,” he says. Over the years, Jim has developed spreadsheets to enter site information and calculate the best features and ele ments for a specific site. Key data at the outset of the irrigation design includes the field location, total number of acres to be irrigated, water source, and power source. His process includes beginning to design the end gun and working his way back to pump selection. “If you need to apply 800 gallons per minute on a field, I will calculate how much pressure is required at that end gun,” Jim says. “Then I work back ward, calculating the friction loss in the pipeline through Total Dynamic

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