Pivot maintenance should be performed in the winter, by carrying out a series of checks to make corrections and get the most out of the Pivot system.
Center Pivot irrigation systems and linear irrigation systems can reach up to 90-95% efficiency with 85% uniformity (minimum acceptable level before the system needs maintenance or replaced emitters).
How is the installed sprinkler package currently performing?
The main goal of Pivot maintenance is to ensure that the predefined flow in each sprinkler is operating according to the machine chart, which requires leaving the working pressure and the nozzle size of each emitter unaltered.
The most common problems include clogged or badly worn nozzles, pressure regulators that are not working properly or are clogged, and incorrect installation. Visually, it is not easy to identify regulators that aren’t working properly, although they sometimes lose water from the sides when their external structure fails.
A malfunctioning regulator can lead to a sprinkler pressure that is too high. An emitter that releases a finer stream of water, or an emitter that rotates faster than adjacent emitters, may indicate that the regulator is underperforming. When a regulator is not working well, the emitters will release larger drops, their rotation speed will be slower, and the diameter of the spray pattern will be smaller.
Pivot maintenance tips to reduce downtime
It is important to check that the emitters are working properly from time to time throughout the season. It is best to do so at the beginning or end of the day, when the sun is lower. This is the best light for identifying differences among emitters.
By measuring the flow of a few randomly selected emitters, you will be able to judge the overall condition of the sprinkler package. This can be done using a container with a scale and a timer, like when calibrating a spray nozzle. You will able to calculate the flow of an emitter and compare it with the center Pivot nozzle chart. Any deviation above or below 10% indicates that there is an issue. You will have to identify the cause and correct the issue. The most common causes of low flow are plugging at the nozzle or before the regulator, plugged regulator, or low operating pressure of the system. High flow usually indicates poorly functioning pressure regulators or worn nozzles.
It is important to monitor the internal pressure of the machine’s pipes throughout the year. Check that the measurements made with a manometer (at the Pivot head and at the end of the system) match those indicated in the sprinkler chart calculated by computer.
A flowmeter is another very useful tool for ensuring that the output flow of the sprinklers, regulators and end guns match the figures on the center Pivot nozzle chart. If the pressure and flow readings change throughout the season, there are likely issues with the sprinkler package.
Performance maps and aerial photos can also be used to identify emitters that are not working properly.