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 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.

 

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

 

Your figures:

Tractor gear___________ Engine revs.___________

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

 

 

Air Blast Sprayer Calibration – use clean water

  1. Pressure check

    2. Place the pressure gauge on the nozzle fitting farthest away from the pump and turn the sprayer on. If pressure is lower at the nozzle than specified, increase pressure at the regulator.

    Pressure at nozzle ___________________psi

    Pressure at sprayer gauge ___________________psi

  2. Nozzle output
  1. Use a flow meter (obtainable from Gemplers, Spraying Systems, etc.) attached to individual nozzles OR
  2. Connect hoses to each of the nozzles and measure the flow from each nozzle into a calibrated jug.

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

 

Formula: Total GPM X 495/mph X row spacing (ft)= GPA

                                                    Your figures: (     GPM X 495)/(    mph X    ft) = GPA