1. Unraveling the Mysteries
Of Sprayer Calibration

2. Sprayer Calibration Herbicides powerful tools
Accurate application essential
Many modern herbicides applied at low rates
Ounces of product per acre
Liquid or dry weight
Under- or over-application problematic
Poor weed control
Excessive collateral damage
Proper sprayer calibration key to applying an appropriate dose

3. Sprayer Calibration Factors that influence sprayer output:
Nozzle flow rate
Orifice size of nozzle
Pressure
Ground speed
All other things remaining constant, output decreases as ground speed increases
Effective spray width
Boom width
Number of nozzles

4. Sprayer Calibration Calibration methods: Spray known area with water
Determine amount water used
Calculate rate per acre
Stationary method with water
Determine output of each nozzle
Should be within 5% of one another
Replace worn nozzles!!!
Calculate average nozzle output/minute
Measure boom width
Determine ground speed
Either of these will provide the sprayer output
Still need to calculate how many acres will be covered by a tank
And how much herbicide to add for an appropriate rate

5. Internet Option www.Teejet.com Calculator Calibration calculator
Application rate
GPM per nozzle
MPH of sprayer
Nozzle spacing

6. Sprayer Calibration Backpack Sprayer mathless calibration (BASF):
Measure 18.5 by 18.5 ft (1/128th acre; 1 fl oz = 1/128th gallon)
Carefully spray and measure time taken to cover area in seconds
Spray into a calibrated bucket for that number of seconds and measure the volume in oz
The number of oz collected equals the gallons per acre sprayer output
Still must determine area covered by one tank to determine how much herbicide to add to sprayer

7. Sprayer Calibration Dimensional analysis:
Multiplication of knowns with unity values
Unity values = 1
12 inches per foot
5,280 feet per mile
43,560 square feet per acre
128 fluid ounces per gallon
3,756 milliliters per gallon
Add unity values to create a series of factors with associated “units” such that all units cancel out during multiplication leaving only the units desired

8. Dimensional Analysis Example: A car travels 55 feet per second;
How fast is it traveling in miles per hour?

9. Dimensional Analysis Example: A car travels 55 feet per second;
How fast is it traveling in miles per hour?
Known value:
55 ft
sec

10. Dimensional Analysis Example: A car travels 55 feet per second;
How fast is it traveling in miles per hour?
Known value:
Unity value:
55 ft
60 sec
sec
min

11. Dimensional Analysis Example: A car travels 55 feet per second;
How fast is it traveling in miles per hour?
Known value:
Unity value:
Unity value:
60 min
55 ft
60 sec hr
sec
min

12. Dimensional Analysis Example: A car travels 55 feet per second;
How fast is it traveling in miles per hour?
known value:
unity value:
unity value:
unity value: mi
55 ft
60 sec
60 min
5,280 ft hr
sec
min

13. Dimensional Analysis Example: A car travels 55 feet per second;
How fast is it traveling in miles per hour?
known value:
unity value:
unity value:
unity value: mi
37.5 mi
55 ft
60 sec
60 min =
5,280 ft hr hr
sec
min

14. Sprayer Calibration Known Area Method
Single nozzle sprayer:
Measure out 100 square feet;
10 ft by 10 ft
Measuring in a weed patch beneficial
Fill sprayer about half full, but exact volume known;
Pump up sprayer and spray marked area just like would spray weeds;
Measure amount of water used;
Amount used to spray 100 sq ft
Can calculate rate per acre and then percentage of an acre sprayer will treat

15. Sprayer Calibration Example
Known Area Method
15 fl oz per 100 ft2:
15 fl oz
gallon
43,560 ft2 =
100 ft2 A
128 fl oz

16. Sprayer Calibration Example
Known Area Method
15 fl oz per 100 ft2:
15 fl oz
gallon
51 gal
43,560 ft2 = A
100 ft2 A
128 fl oz

17. Sprayer Calibration Example
Known Area Method
15 fl oz per 100 ft2:
15 fl oz
gallon
51 gal
43,560 ft2 = A
100 ft2 A
128 fl oz
What part of an acre will a 3 gal capacity sprayer cover? A
3 gal =
51 gal
tank

18. Sprayer Calibration Example
Known Area Method
15 fl oz per 100 ft2:
15 fl oz
gallon
51 gal
43,560 ft2 = A
100 ft2 A
128 fl oz
What part of an acre will a 3 gal capacity sprayer cover? A
3 gal
0.059 A =
51 gal
tank
tank

19. Sprayer Calibration Example
Known Area Method
15 fl oz per 100 ft2:
15 fl oz
gallon
51 gal
43,560 ft2 = A
100 ft2 A
128 fl oz
What part of an acre will a 3 gal capacity sprayer cover? A
3 gal
0.059 A =
51 gal
tank
tank
How much herbicide to add if rate is 1 qt per acre?
0.059 A
1 qt
946 ml =
tank A qt

20. Sprayer Calibration Example
Known Area Method
15 fl oz per 100 ft2:
15 fl oz
gallon
51 gal
43,560 ft2 = A
100 ft2 A
128 fl oz
What part of an acre will a 3 gal capacity sprayer cover? A
3 gal
0.059 A =
51 gal
tank
tank
How much herbicide to add if rate is 1 qt per acre?
0.059 A
1 qt
946 ml
56 ml =
tank A qt
tank

21. Sprayer Calibration Known Area Method
Boom sprayer:
Boom width ft
Filled 500 gallon tank half full with water
Spray 500 ft & used 3.4 gallons of water
500 ft w/16.67 ft boom = 8,276 ft2
What is sprayer output in gallons per acre?
3.4 gal
8,276 ft2

22. Sprayer Calibration Known Area Method
Boom sprayer:
Boom width ft
Filled 500 gallon tank half full with water
Spray 500 ft & used 3.4 gallons of water
500 ft w/16.67 ft boom = 8,276 ft2
What is sprayer output in gallons per acre?
3.4 gal
43,560 ft2 = A
8,276 ft2

23. Sprayer Calibration Known Area Method
Boom sprayer:
Boom width ft
Filled 500 gallon tank half full with water
Spray 500 ft & used 3.4 gallons of water
500 ft w/16.67 ft boom = 8,276 ft2
What is sprayer output in gallons per acre?
3.4 gal
17.8 gal
43,560 ft2 = A
8,276 ft2 A

24. Sprayer Calibration Another stationary method:
Measure boom width in feet or inches
Measure total nozzle output per minute
Divide by 128 to determine GPM
GPA = 5940 x GPM/MPH x nozzle spacing (5940 spacing inches; 495 spacing feet)
Still must determine how many acres per tank and how much herbicide to add

25. Colorado State University
Weed Science