35HARDI
®
COMMANDER OPERATOR’S MANUAL
Calibration
Calibration
WARNING:
ALWAYS CALIBRATE YOUR
SPRAYER WITH CLEAN WATER ONLY! IN
ADDITION, WEAR PROTECTIVE CLOTHING
WHEN CALIBRATING YOUR SPRAYER!
Why must you calibrate a sprayer?
A nozzle selection chart will tell you what application
rate you should expect. Variations due to nozzle wear,
errors in pressure adjustment, and tractor speedometer
can result in a possible error in application rate.
How do you calibrate a sprayer?
Calibration kits are available from HARDI
®
, #818493 for
US gallons & #818492 for metric calibration.
Following are some tips to remember when using the
calibration kit method:
• When determining the length of time required to drive
the recommended distance, drive in actual field
conditions with a half-full tank.
• Repeat the test several times, each time avoiding the
tracks from the previous test. Take the average of the
times recorded.
• Calibration of the sprayer should be completed at the
beginning of the season and repeated after every 2 to
3 full days of spraying, and every time you change
volume rate or use new nozzles.
• Before you calibrate, check the flow of each nozzle. If
it puts out more than 10% of its original volume,
replace it.
Select your calibration method- Ounce method or
Formula method.
Then follow the steps described below:
Ounce Method
1. Determine how long it takes you to cover the test
strip. Use the following chart to determine the length
of your test strip. Row width for broadcast application
is equal to your nozzle spacing. For your drop nozzle
or band application, use row spacing.
Row width or nozzle spacing (in.) Distance (ft.)
40 102
38 107
36 113
34 120
32 127
30 136
28 146
26 157
24 170
Row width or nozzle spacing (in.) Distance (ft.)
22 185
20 204
18 227
16 255
14 291
2. Measure the amount of time it takes you to travel the
test strip when throttle is set at spraying speed.
3. In a container (with oz. measurements), catch the
spray from on nozzle for that amount of time. For
drop or band nozzles, catch the spray from all
nozzles for the row.
4. Read the ounces in the container. That is the actual
U.S. GPA applied (ounces - GPA).
Formula Method
1. Check your spraying speed. Measure a test strip of
at least 200 feet (300 feet is ideal). Travel the
distance at the speed you plan on spraying and
record the time it takes to travel the distance. Read
from the chart or use the formula to find your exact
travel speed.
Travel Time (in seconds)
Speed in MPH 200 ft. 300 ft.
3.0 45 68
3.5 39 58
4.0 34 51
4.5 30 45
5.0 27 41
6.0 23 34
7.0 19 29
7.5 18 27
8.0 17 26
9.0 15 23
Formula:
distance (ft.) x 0.68
= MPH
seconds
2. Calculate the required nozzle output. Use either the
nozzle wheel (if nozzle spacing is 20 inches), or this
formula:
Formula: Formula:
GPM =
GPA x MPH x W (in.)
GPM =
10 x 7 x 20
= .24 GPM
5940 5940
Note:
W= • Nozzle spacing (in inches) for broadcast applica-
tion.
• Row spacing (in inches) divided by number of
nozzles per row for drop nozzle application.
• Sprayed band width or swath width (in inches) for
band application divided by number of nozzles
per band.
• Note that on the nozzle wheel, W = 20 inches.
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