Page 213 - Florida Pest Control Examinations

CALCULATIONS

The state tests include examples of calculations to be made in the field, most of which relate
to agricultural settings. The following formulas are from state publications, and should be
representative of those found on the tests. Examples are given to show how the calculations
will work out.

SPRAYER CALIBRATION

Calibration of your spraying equipment is very important. It should be done daily or whenever
you change chemicals to ensure application of the proper dosages. Applying incorrect
amounts may do more damage than good and always wastes time and money.
Adjustable factors that determine calibration and affect application rate include: speed,
pressure, nozzle size, nozzle type and wear, or a combination of these. Speed is the easiest
and most common adjustment. Examples are given in red so that you can see how the
calculations work out.

Three Calibration Methods

METHOD I

A. To measure nozzle flow rate:
(in gallons/per nozzle/per min.)= ounces collected for 1 min. from 1 nozzle 20 oz./min.= .15gal./nozzle/min.
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B. To calculate gallons per acre =
Gal./nozzle/min. x 12 x 43,560 .15x12x43,560 = 327 gal. per acre
nozzle spacing x speed 48 in. x 5 MPH
Where:
• nozzle spacing = inches between the nozzles and speed is figured= MPH x 88
• Test all nozzles to ensure uniformity and replace any that have greater than 10% variation from the average
of all nozzles.

METHOD II

A. First, spray 660 feet at the desired speed and pressure.

B. Then, determine the amount of spray discharged (water) while traveling this distance:

• Collect the spray from each nozzle and add it together; or
• Mark the beginning level of water in the tank and measure the amount of refill back to the beginning level
after spraying.

C. Use this formula:
(to calculate gallons/acre) = gallons used in 660 feet x 66 12 gal. X 66=792 =79.2 gal. per acre
swath width (ft.) 10

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