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Boom Sprayer Calibrator

Calibrate, Download, Print

  1. Select a nozzle.
  2. Calculate nozzle size.
  3. Compare required with actual output.
  4. Prepare the spray mixture.
  5. Print this worksheet.

North Willamette Research & Extension Center, Oregon State University

Proper setup and calibration of your sprayer is necessary for an accurate pesticide application rate. Sprayer calibration should be done at least once per season if the sprayer is used for only one type of application. But if you adjust the application rate (gallons per acre) or change nozzles for a different type of application, the sprayer must be recalibrated.

1. Select a nozzle.

Make sure the nozzles are the appropriate style and size for the next spray application. Nozzles are designed for specific spray applications: broadcast, band, or directed spray. The list below outlines the most common nozzle styles for each type of application.

Style

Broadcast flat (fan), flood, full cone
Band even, hollow cone
Directed hollow cone, full cone

Arrangement

Proper nozzle arrangement is critical for a uniform and accurate application. Check the following items:

  • spacing along boom
  • angle of alignment along boom (influences spray pattern)
  • height above target
  • number of nozzles/row for directed applications

Size

Nozzle size and spray pressure determine a nozzle’s output (gal/min), which together with tractor speed, determines the sprayer’s application rate (gal/acre). Correct nozzle size must be selected to deliver the desired application rate. Remember that nozzles wear out over time, enlarging the orifice and increasing their output.

2. Calculate Nozzle Size.

Enter known quantities & calculate nozzle output
Measure speed by conducting a test spray in your field, with water, using your standard gear, throttle, and pressure guage settings. Enter speed:

Enter gallons per acre from pesticide label “Instructions For Use”:

Enter Area, in feet, treated by one nozzle:

For multiple-nozzle, directed-spray applications, divide spray width by number of nozzles treating that area. Enter number of nozzles:

required nozzle output in gallons per minute (GPM):

( ft/min X gal/acre X ( ft ÷ nozzles) ) ÷ 43,560 ft2/acre
=

3. Compare required with actual output.

Enter measurements & calculate actual output Measure output of each nozzle:

  1. Partially fill spray tank with water.
  2. Run sprayer at your standard spray pressure and collect nozzle output for 20 sec. in a jar calibrated in fluid oz.
  3. Measure the volume collected in 20 seconds.

the actual nozzle output:

fl.oz X 3 ÷ 128 fl.oz/gal =

For each nozzle, compare:

Required nozzle output (D)

with

Actual nozzle output (F)

Recommendations:

  • Change nozzle size if output is 20% greater or less than your calculated nozzle size, then recalibrate.
  • Replace worn nozzles having output 10% higher than a new nozzle (same size) at your pressure.
  • Make fine adjustments to output by adjusting tractor speed or spray pressure, then recalibrate.
  • Observe nozzle spray for correct pattern, replace if needed.

4. Prepare the spray mixture.

Calculate Quantity

the quantity of pesticide needed in spray mixture:

÷ =

Then…

X =