1. Calibration of your Field Sprayers using Shortcut Methods
Pesticide Education Program
Montana State University Extension

2. Calibration Benefits You!
You will not under apply
Maintains the Best Pest Control
Will not over-apply
Environmental and human safety risks
No need to re-apply
Effective use of time
Save $$

3. Follow Along Using MSU Reference Materials
Use the MontGuide titled “Calibrating Ground Sprayers Using Shortcut Methods
Save time with the 5940 method
128th Acre Method
Backpack Sprayers
Boom Sprayers
Shortcut for Broadjet Sprayers

4. Suggested Calibration Tools
Stopwatch
Measuring Tape
Measuring Container
Pencil and paper
Source of fresh water

5. 5940 Method can be used to Select Appropriate Nozzles
Can get you close to your target GPA.
Your product label often describes the proper GPA (gallons per acre) for your sprayer.
example. 20 GPA is recommended
Use the 5940 METHOD to find nozzle size

6. What is the 5940 method? GPA = Gallons Per Acre (product label)
GPM = Gallons per Minute collected from a single nozzle (Make sure all nozzle are within a 10% range.)
5940 is a constant
MPH = Field Speed
W = 1) width between nozzles in inches or 2) width of a broadjet swath in inches.

7. Selecting the Appropriate Nozzle
GPM = GPA * W * MPH / 5940
Let’s say you need to spray 20 GPA, you have 30” spaced nozzles, and you will drive 5 mph.
GPM = 20 GPA * 30” * 5mph / 5940
0.505 or 0.5 GPM nozzles needed
Purchase nozzles rated at 0.5 GPM!

8. Using 5940 to get an idea what your field speed should be
Let’s say you need to spray 10 GPA, you have 24” spaced nozzles, and your nozzles deliver .2 gallons per minute.
Speed = (GPM x 5940) / (GPA x W)
Speed = 1188 / 240
Field speed = 4.95 miles per hour

9. Shortcut Method to Calibrating Backpack Sprayers

10. Backpack Sprayer (Calibrating GPA) 128th Acre Method
Use water when calibrating
Use same nozzles and filters as when spraying
Measure an 18 ½ by 18 ½ ft area.
Spray area with water and time how long it takes
Constant speed and constant pressure
Spray into container for same amount of time.
Ounces = Gallons Per Acre Applied

11. Sample Scenario Using 128th Acre Scenario
Takes 10 seconds to spray 128th Acre
In 10 seconds you spray 10 ounces into a container.
What is the GPA output?
10 GPA

12. SHORTCUT METHOD TO CALIBRATING BOOM SPRAYERS
Find GPA? How?

13. Check nozzle spacing and height

14. Worn Spray Tips

15. Boom Level or Nozzle Angle Correct

16. Verify that all nozzles are equal

17. Due to problems with wear you must test uniformity of nozzles annually
Check nozzle output for 1 minute and get average
If each nozzles output is not greater or less than 10% off of average, all is well.
How?

18. 10% error level To find 10% Find your average…48 oz
Move the decimal place one space to the left = 4.8 This is a 10% error
Now add 4.8 to 48 for +10%
Subtract 4.8 from 48 for -10%
10% Error range = 43.2 and 52.8
Any nozzle output between 43.2 and 52.8 is OK!

19. GPA for Boom Sprayer cont. Shortcut Method
1st – Determine Nozzle output is same.
2nd – Flag out Course Length based on your nozzle spacing
18” = 227’ course length
20” = 204’ course length
30” = 136’ course length
40” = 102’ course length
Or 340 / spacing in feet
3rd - Drive course in gear and rpm
you will use when spraying and
time yourself. Repeat 2 – 3 times.

20. GPA for Boom Sprayer cont..
4th - Collect liquid from 1 nozzle for this amount of time
5th - Ounces of liquid collected = GPA

21. Sample Scenario Boom Sprayer
18” wide nozzles, 6 nozzles
What to do?
Travel 227’ and time
30 seconds
Measure amount delivered in that 30 seconds
15 ounces in 30 seconds
15 GPA

22. Broadjet Sprayers Determine Test Strip Distance:
Divide your spray swath (ft) into then multiply times 10. This is your test strip distance (example: / 30 feet = x 10 = feet.
Run test strip and time
(it took 25 seconds to drive ft).
Collect your broadjet output (ounces)
For the time it took to drive test strip
(Collected 130 ounces in 25 seconds).
Divide the amount collected in ounces by 10.
This equals GPA.130 / 10 = 13 GPA

23. Sample Scenario - Broadjet
25’ wide swath, 1 Broadjet
What to do?
Travel 136’ and time
27 seconds
Measure solution delivered in seconds
200 ounces in 27 seconds
What is the GPA?
20 GPA

24. Fine tune your GPA by adjusting:
Speed
Slower speed increases output
Pressure
Only slight adjustments
Nozzle size
Use 5940 to get you close
Not meant for fine adjustments
Nozzle spacing
Often preset

25. You know GPA, now how much solution do you need?
Acres * GPA = Volume in Tank
10 acres * 30 GPA = 300 Gallons

26. How much chemical do you need?
Acres * product rate = Total Product
Product Rate = 2 pints / Acre
You will be spraying 10 acres
20 pints of product

27. Sample Questions You have an output of 20 GPA
You need to spray 300 acres
#1 - How much of a spray mixture will you need?
6000 gallons
You need to apply 2 oz / acre of Warrior 1E.
#2 - How much product do you put in tank?
600 oz of Warrior

28. Questions Continued
#3 You have 20” nozzles and travel 204’ in 25 seconds. What next?
-You collect 10 ounces in 25 sec.
-What is your GPA?
GPA = 10 GPA

29. Question continued
You are trying to select a nozzle and it reads XR11004B.
#4 What type of nozzle is this?
Extended Range Flat Fan
#5 What angle of spray mist is emitted from these nozzles?
110 degrees
#6 How low can you hold this boom at this spray angle?
15 – 18”
#7 How many gallons per minute does this nozzle emit at a standard pressure?
.4 Gallons Per Minute (standard 40 PSI)
#8 What material is this?
Brass
#9 What is the nozzle life of this nozzle?
Poor

30. Questions?
#10: What width and length would easily qualify for using the short cut 128th acre method for calibrating your backpack sprayer?
18 1/2 x 18 ½ feet

31. Making this even more easy with the ‘Calibration Assistant’.
Contains the tools to make calibration easier.
Can aid in testing
output of nozzles
Aids in determining
output (GPA) for
many types of
equipment
Conversion Page
Instructions
Determines
product to add to tank
acres you can cover

32. Aids in Testing Uniform Nozzle Flow
Critical prior to assessing output of boom sprayers.
Calibrations Assistant Makes the math easier, while walking applicators through the process.

34. Aids in Determining Output of Boom Sprayers

36. Aids in Determining Hand Sprayer output (GPA)

38. Aids in Determining Broadjet Sprayer Output

40. Aids in Determining the Output of your Rotary or Drop Spreaders

42. Includes a Spreadsheet to Aid in Conversions

44. Practical Tool Not meant for initial training purposes
Important that applicators have a base understanding of calibration
Not meant as a crutch which allow applicators in initial training to slack
Support tool useful for
Certified Applicators who have some base knowledge

45. Available from the MSU Distribution Center
The Calibration Assistant CD
$3.00 copy
Distribution Center Communications & I.T. Po Box Bozeman, MT Tel: (406) Fax: (406) Location: 115 Culbertson

46. Questions