2.1 Calibration of Application Equipment

Step 1. Travel Speed Calibration

Travel speed is a critical factor in maintaining accurate application rates and will influence spray deposition. The slower a sprayer travels, the greater the uniformity in spray deposition. Although there is inconsistency in research results that try to determine the effect of travel speed on average spray deposition, all studies to date have been in agreement that the higher the travel speed, the greater the variability in spray deposit. Variation in spray deposit is an important factor where uniformity of spray coverage throughout the canopy is required. Conclusions from research were drawn using travel speeds of 1-4 mph.

Factors that will affect travel speed include:

·         weight of sprayer

·         slope of terrain

·         ground conditions traveled over (wheel slippage!)

The best way to measure travel speed is to operate the sprayer with the tank half filled with water on the same type of terrain as the sprayer will be operated on.

Set up test course at least 100 feet long, measure the course with a tape measure. Do not pace the distance. The longer the course the smaller the margin of error. Run the course in both directions.

Use an accurate stop watch to check the time required to travel the course in each direction. Average the two runs and use the following formula to calculate the speed in MPH.

Your figures:

Tractor gear__________ Engine revs. _________

Step 2.A. Record the inputs (for acre basis)

Your figures

Example

Nozzle type on your sprayer

(all nozzles must be identical)

_______________

110 04 flat fan

Recommended application volume

(from manufacturer’s label)

_______________

20 gallons/acre

Measured sprayer speed

_______________

4 mph

Nozzle spacing

_______________

20 inches

Step 2.B. Record the inputs (for 1000 sq. ft. basis)

Your figures

Example

Nozzle type on your sprayer

(all nozzles must be identical)

_______________

110 04 flat fan

Recommended application volume

(from manufacturer’s label)

_______________

1 gallon/1000 sq. ft.

Measured sprayer speed

_______________

4 mph

Nozzle spacing

_______________

20 inches

Step 3.A

Calculate the required nozzle output (acre basis)

Example:
GPM = 20 X 4 X 20  =  1600  =  0.27 GPM
                   5940            5940

Formula:
GPM =  GPA X mph X nozzle spacing
                          5940 (constant)

Your figures
GPM=           X           X             =  ________   =        GPM
                         5940                           5940

Step 3.B

Calculate the required nozzle output

(1000 sq. ft. basis)

Example:
GPM = 1 X 4 X 20 =     80  =  0.59 GPM

                           136          136

Formula:
GPM = Gal/1000 sq. ft.  X mph X nozzle spacing

                                 136 (constant)

Your figures:
GPM =            X           X           .  =  ________  =                  GPM

136                        136

Step 4. Operate the sprayer

·         Set the correct pressure at the gauge using the pressure regulating valve.

·         Collect and measure the output of each nozzle for one minute.

·         The output of each nozzle should be the approximately the same as calculated in Step 3 above. Remember 128 fl. ozs = one gallon. If output has been calculated at 0.27 GPM then output is 128 multiplied by 0.27 = 34.5 fl.ozs in one minute.

·         Consult the nozzle manufacturers handbook for nozzle flow and pressure.

·         Replace all nozzle tips which are more than 5% inaccurate.