Crop and Pest Management Guidelines

7.3 Sprayer Calibration

Videos showing calibration and nozzle selection may be found on the internet at www.youtube.com. Type in: "Calibration of airblast sprayers for orchards part 1 selecting and changing nozzles" or "Calibration of airblast sprayers for orchards part 2 measuring liquid flow"

7.3.1 Travel Speed Calibration

Sprayer travel speed influences spray deposition and is a critical factor in maintaining accurate application rates. Studies to determine the effect of travel speed on average spray deposition agree that the higher the travel speed, the greater the variability in spray deposit. This variability 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 affecting 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 half full of water over the same type of terrain on which the actual sprayer will be operated.

Using a tape measure, set up a test course at least 100 feet long. 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 to calculate the speed in MPH.

Your figures:

Tractor gear___________ Engine revs.___________

An alternative to using the above method is to purchase a hand-held GPS receiver. A number of systems are available from electronics stores, hunting equipment suppliers, and online. Costing ranges from $80-150. The small device is portable so can be used in all tractors to determine forward speed in specific tractor gears at known engine RPM.

7.3.2 Airblast Sprayer Calibration

- use clean water

1. Pressure check
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
Use a flow meter (obtainable from Gemplers, Spraying Systems, etc.) attached to individual nozzles OR

connect hoses to each of the nozzles and measure the flow from each nozzle into a calibrated jug. Record and total your results using Figure 7.3.1.

Calculate gallons per acre using the following formula.

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

Figure 7.3.1. Airblast Sprayer Calibration

7.3.3 Calibrating a Kinkelder Sprayer

-use clean water

This figure should be set on both scales.

Both taps should be set on the distribution conduit in such a way that the index is set on the sign 162 on the index plate of the distribution conduit. The emission indication on the index plate has been fixed at a working pressure of 21 lbs (1.5 bar).

Check the output of the sprayer:

1. Divide the gallons/hour figure obtained above by 60 to give output/minute e.g. 162 gpm divide by 60 = 2.7 gallons/minute total of left and right side then divide 2.7 gallons/minute by 2 = 1.35 gallons/minute/side.

2. Remove the plastic pipes from the nozzles on the left or right side, tie together and place in a measuring jug.

3. Run the sprayer for one minute at correct engine speed, collecting the output in a measuring jug

Remember 128 fl. ozs in one gallon. Example: If the output of one side has been measured at 173 fl.ozs, then output is divided by 128 = 1.35 gallons per minute.

4. Then check the output of the opposite side.

7.3.4 Calibrating an AgTec Sprayer

-use clean water

1. Calculate the gallons/minute/side:

2. Check AgTec tables for correct meter setting, select the gal/min as calculated above, and then find meter setting, e.g. meter #12 @ 30psi gives 1.34 gallons/min.

3. Remove the hoses from the nozzles on the left or right side, tie together, and place in a measuring jug

4. Run the sprayer for one minute at correct engine speed, collecting the output in a measuring jug

Remember 128 fl. ozs. in one gallon. Example: If the output of one side has been measured at 173fl.ozs, then output is divided by 128 = 1.35 gallons per minute.

5. Then check the output of the opposite side.

7.3.5 Boom Sprayer Calibration

-use clean water

Step 1. Check your tractor/sprayer speed

Your tractor sprayer speed:

Step 2. Record the inputs

Step 3. Calculate the required nozzle output.

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 approximately the same as calculated in Step 3 above.

Replace all nozzle tips that are more than 5% inaccurate.

7.2 Preparing the Airblast Sprayer for Work

7.4 Spray Nozzle Types