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Get your sprayer fine-tuned

The marketplace is calling upon you to raise a whale of a crop this year. So, every little bit will help.

That includes your sprayer. And now, with the start to planting as much as a month behind the blistering pace of 2012, it's a perfect window to take some time to make sure your sprayer's fine-tuned and ready for the growing season.

"Higher pesticide costs and new chemicals designed to be used in lower doses make accurate application more important than ever," says Ohio State University ag engineer Erdal Ozkan. "There is no better time than early spring to take a closer look at your sprayer."

Ozkan recommends the following steps to make sure your sprayer's in good shape this spring.

  • Double-check your sprayer for mechanical problems before you start using it. You won’t have time to do this when planting is in full swing.
  • Clean the sprayer tank thoroughly and make sure nozzle filters are clean.
  • Clean spray nozzles, check their flow rates, and replace the ones that are spraying more than 10% of the original output.
  • Check the agitator in the tank to make sure it’s working properly.
  • Run water through the spray system to make sure everything is working properly
  • Find out if the sprayer is delivering the proper application rate (gallons per acre).  

One of the most important things to do to your sprayer before the season begins is get it calibrated. But, before you can even begin that process, make sure you're running nozzles that are clean and consistent.

"Nozzles wear off through extended use causing over application, or some nozzles are plugged. Clean all the plugged nozzles. Check the output of all the nozzles for a given length of time at a given spray pressure. Compare output from each nozzle’s output with the expected output shown in the nozzle catalog for that nozzle at the same pressure," Ozkan says. "Replace the nozzles showing an output error of more than 10% of the output of the new nozzle."

Once you're ready to calibrate, you've got a lot of options, procedure-wise. But, the basic premise is the same: "Regardless of which method you choose, it usually doesn’t take more than 30 minutes, and only three things are needed: a watch showing seconds, a measuring tape, and a jar graduated in ounces," Ozkan says.

He recommends following these steps when calibrating:

  1. Fill the sprayer tank (at least half full) with water.

  2. Run the sprayer, inspect it for leaks, and make sure all vital parts function properly.

  3. Measure the distance in inches between the nozzles.

  4. Measure an appropriate travel distance in the field based on this nozzle spacing. The appropriate distances for different nozzle spacing is as follows: 408 ft for a 10-inch spacing, 272 ft for a 15-inch spacing, 204 ft for 20-inch spacing, 136 feet for a 30-inch spacing, and 102 feet for a 40-inch spacing.

  5. Drive through the measured distance in the field at your normal spraying speed, and record the travel time in seconds. Repeat this procedure and average the two measurements.

  6. With the sprayer parked, run the sprayer at the same pressure level and catch the output from each nozzle in a measuring jar for the travel time required in step 5 above.

  7. Calculate the average nozzle output by adding the individual outputs and then dividing by the number of nozzles tested. The final average nozzle output in ounces you get is equal to the application rate in gallons per acre. For example, if you catch 15 ounces from a set of nozzles, the actual application rate of the sprayer is equal to 15 gallons per acre.

  8. Compare the actual application rate with the recommended or intended rate. If the actual rate is more than 5 percent higher or lower than the recommended or intended rate, you must make adjustments in either spray pressure or travel speed or in both. For example, to increase the flow rate you will need to either slow down, or increase the spray pressure. The opposite is true when you need to reduce application rate. As you make these changes stay within proper and safe operating condition of the sprayer. Remember increased pressure will result in increasing the number of small, drift-prone droplets. Using the trial-and error method to eventually reach the intended application rate takes some time. If you follow the equations given in Extension Publication AEX-520 on Calibration you can find optimum travel speed and pressure much faster.

  9. Recalibrate the sprayer (repeat steps 5-8 above) until the recommended application error of +5% is achieved.

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