Sprayer Calibration

Travel Speed Calibration

Travel speed is a critical factor in maintaining accurate application rates and will influence spray deposition depending on location within the canopy. 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 to be pulled
  • slope of terrain
  • ground conditions traveled over (wheel slippage!)

The best way to measure travel speed is to pull a sprayer with tank half filled with water on the same type of terrain that 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 stopwatch 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.

 

Formula: MPH = (ft. traveled/sec. traveled)  X   (60/80)

 

Your figures:

Tractor gear___________ Engine revs.___________

MPH = (ft. traveled/sec. traveled)  X   (60/80)  = ________

 

 

Boom Sprayer Calibration - use clean water

Step 1. Check your tractor/sprayer speed

Formula: MPH = (ft. traveled/sec. traveled)  X   (60/80)

Your tractor sprayer speed:

                            MPH = (ft. traveled/sec. traveled)  X   (60/80)  = ________

 

Step 2. Record the inputs

Your figures                             Example

Nozzle type on your sprayer ________________ 110 04 flat fan

(all nozzles must be identical)

 

Recommended application volume ________________ 20 GPA

(from manufacturer’s label)

 

Measured sprayer speed ________________ 4 mph

Nozzle spacing ________________ 20 inches

 

Step 3. Calculate the required nozzle output.

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

                                5940 (constant)

Example: GPM = (20 X 4 X 20)/(5940) = 1600/5940 = 0.27 GPM

 

Your figures: GPM = (   X    X    )/(5940) =      /5940 =       GPM

 

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.

Replace all nozzle tips, which are more than 10% inaccurate.