Southeastern U.S. Vegetable Crop Handbook - 2023 - 122

NOZZLE METHOD
1. Accurate ground speed is very important to good calibration
with the nozzle method. For tractor-mounted sprayers,
set the tractor for the desired ground speed and run
the course at least twice. For backpack sprayers, walk the
course and measure the time required. Walk across the
course at least twice. Average the times required for the
course distance and determine ground speed from Equation
1.
2. Calculate the nozzle discharge rate based on the application
rate required the ground speed over the test course,
and the nozzle spacing, spray width, or spray swath of the
sprayer. For nozzle spacing or spray width measured in
inches.
Equation 7. Discharge Rate =
Application Rate x Speed x Spray Width
5,940
For spray swath measured in feet:
Equation 8. Discharge Rate =
Application Rate x Speed x Spray Swath
495
Set the sprayer and determine the average nozzle rate.
3. Compare the rate calculated to the average rate from the
nozzles. If the two don't match, choose the appropriate
adjustment and reset the system.
4. Recheck the system if necessary. Once you have the accuracy
you want, calibration is complete.
128TH ACRE METHOD
1. The distance for one nozzle to cover 128th
of an acre must
be calculated. The nozzle spacing or spray width in inches
is used to determine the spray distance. Spray distance
is measured in feet. On backpack sprayers, be sure to
measure the full width sprayed as you walk forward. Use
Equation 9.
Equation 9. Spray Distance =
4,084
Spray Width
2. Measure the spray distance on a test course in the field.
Check the ground speed as you travel across the course.
Be sure to maintain an accurate and consistent speed.
Travel the course at least twice and average the time to
cover the course.
3. For backpack sprayers, collect the output from the nozzle
for the time measured in step 2. For tractor-mounted
sprayers, park the sprayer, select the nozzle closest to the
average, and collect the output for the time determined
in step 4. Ounces collected will equal application rate in
GPA.
4. Compare the application rate measured for the nozzle to
the rate determined in step 3. If the rates are not the same,
choose the appropriate adjustment and reset the system.
5. Recheck the system if necessary. Once you have the accuracy
you want, calibration is complete.
AREA METHOD
1. Determine the distance that can be sprayed by one tank
using the full spray swath measured in feet.
Equation 10. Tank Spray Distance (ft) =
Tank Volume (gal) x 43,560
Application Rate (GPA) x Swath (ft)
2. Lay out a test course that is at least 10 percent of the tank
spray distance from Step 1. Fill the sprayer tank with
water only, mark the level in the tank, set the sprayer as
recommended, and spray the water out on the course. Be
sure to maintain an accurate and consistent speed.
3. After spraying the test course, carefully measure the volume
of water required to refill the tank to the original level.
Calculate the application rate as shown:
Equation 11. Application Rate (GPA) =
Volume Sprayed (gal) x 43,560
Test Course Distance (ft) x Swath (ft)
4. Compare the application rate measured to the rate required.
If the rates are not the same, choose the appropriate
adjustment method and reset the sprayer.
5. Recheck the system. Once you have the accuracy you
want, calibration is complete.
CALIBRATING A GRANULAR APPLICATOR:
PREPARING TO CALIBRATE
Granular application calibration is usually done with the chemical
to be applied. It is difficult to find a blank material that
matches the granular product. Extra care should be taken in handling
this product. Minimize worker exposure and take precautions
against spills during calibration.
To prepare for calibration, follow these steps:
1. Before calibrating, carefully inspected the equipment to
ensure that all components are in proper working order.
Check the hopper, the metering rotor, the orifice, and the
drop tubes. Be sure there are no leaks or obstructions.
2. Determine the type of application required for the
product: ·
* Broadcast: treats the entire area (includes band applications
based on broadcast rates).
* Band: treats only the area under the band.
* Row: treats along the length of the row.
3. Determine the application rate needed: ·
* Broadcast: pounds per acre. ·
* Band: pounds per acre of treated band width. ·
122
2023 Vegetable Crop Handbook for Southeastern United States
Southeastern U.S. Vegetable Crop Handbook - 2023

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