Herbicide Boom Sprayer Calibration Worksheet
Ed Hellman
Texas Cooperative Extension
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. Nozzle selection
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. Determine the required nozzle size (gal/min)
Required information:
Fill in the following known quantities, insert into the equation below, and calculate the result.
(A)_______ft/min. Tractor speed Measure speed (ft/min.) by conducting a test spraying run (use water) through the field using your standard gear, throttle, and pressure guage settings.
(B)_______gal/acre Desired application rate Gallons per acre from pesticide label instructions for use.
(C)_______ft Spray width Area (ft) treated by one nozzle. For multi-nozzle, directed spray applications, divide spray width by number of nozzles treating that area.
Calculate required nozzle output
in gpm
| (A) ____ ft/min. X
(B) ____ gal/acre X (C)____ ft. |
_____________________________________________
43,560 ft2/acre |
= (D)______ gal/min
required nozzle output |
| |
3. Compare required nozzle output with actual output.
Measure output of each nozzle:
- Partially fill spray tank with water.
- Run sprayer at your standard spray pressure and collect nozzle output for 20 sec. in a jar calibrated in fluid oz.
For each nozzle,
measure the volume collected in 20 sec. = (E)_____ fl.oz.
(E) _____ fl. oz. X 3
_________________ = (F)_____ gal/min actual nozzle output
128 fl.oz./gal.
For each nozzle, compare:
Required nozzle output (D)______ gal/min
Actual nozzle output (F)______ gal/min
- 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.
| Desired application rate,
recorded above: |
(B) _______ gal/acre |
| Total volume of spray mixture desired: |
(G) _______ gal |
Pesticide application rate
quantity per acre from the label |
(H) _______ (lb, oz, gal) per acre |
|
(G) ______ gal total volume |
|
______________________
= (I) _____ acres treated |
|
(B) ______ gal/acre |
|
|
|
| (I) _____ acres
X (H) _____ = |
_______ quantity
of pesticide
needed in spray mixture
|
The Texas Winegrape Network was created and is maintained by Edward Hellman,
Department of Horticultural Sciences, Texas A&M University.
http://winegrapes.tamu.edu
© Copyright 2004 Texas A&M University
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