1. Spray Nozzle Selection and Calibration

2. Sprayer Nozzle Selection and Calibration
Author: Tom Reed, Northeast Regional Manager, TeeJet Mid-Tech
For more information, contact:
Dean Slates, Ohio State University Extension, Holmes County, (330) ,

3. Nozzle Functions 1. Regulate Flow 2. Form Droplets
3. Disperse Specific Patterns

4. gpm1 psi1 gpm2 psi2 = Nozzle Capacity and Pressure are Related
If the nozzle delivers 0.2 gpm at 25 psi, it will deliver 0.4 gpm at 100 psi
This means that to double the flow, increase the pressure 4 times.

5. The Nozzle Compromise Increase in pressure gives more nozzle GPM BUT
Increase in pressure gives more driftable fine drops

6. Defining Spray Droplets
For a given pressure, a spray tip will produce a range of droplet sizes
Droplets form the pattern
Droplet size is measured in microns (micrometers)

8. 150m Comparison of Micron Sizes (approximate) 2000m = #2 Pencil lead
850m = paper clip
420m = staple
300m = toothbrush bristle
150m = sewing thread
100m = human hair
150m

9. 1/2x Droplet diameter = 8x Number of droplets

10. 50% less than VMD 50% greater than VMD Volume Median Diameter
Total Volume of Liquid
Volume Median Diameter
50% of the volume of liquid in all the droplets is less than the VMD and,
50% of the total volume is in droplets of size greater than the VMD
(VMD also known as Dv0.5)
50%
less
than
VMD
50%
greater
than
VMD

11. Droplet Size Categories
Initiated by BCPC (British Crop Protection Council)
ASAE (American Society of Agricultural Engineers) Standard 572 currently used
Assigns droplet size category to a spray tip based on spray characteristics
Allows for comparison of droplet size between various tips and manufacturers
Most chemical labels in the future will feature droplet size category recommendations

12. Droplet Size Categories
Category
Symbol
Color Code
Approximate VMD Range
Very Fine VF
Red
< 150
Fine F
Orange
150 – 250
Medium M
Yellow
250 – 350
Coarse C
Blue
350 – 450
Very Coarse VC
Green
450 – 550
Extremely Coarse XC
White
> 550

13. Nozzle Classification System

14. AI TeeJet™ (Air Induction)

16. Mode of action is a major factor in nozzle selection

20. Types of Spray Patterns
Hollow Cone Flat Fan Full Cone

21. Objective is to obtain the lowest CV (Coefficient of Variation) along the boom
30% minimum overlap for uniformity along boom

22. Set the Boom Height using the Manufacturer’s Specifications
The boom height is measured from the top of the plant canopy to the nozzle and is specific for the nozzle spray pattern
Setting boom height. Even with properly calibrated spray nozzles and correct pressure settings, the spray distribution pattern may not be acceptable unless the boom height is properly adjusted. The nozzle spray pattern is designed so that when the boom height is set for the nozzle spacing on the boom, the spray is evenly applied across the boom width. The boom height is measured from the top of the plant canopy to the nozzle and is specific for the nozzle spray pattern (for example, a 110 degree flat fan, or 80 degree or 60 degree spray pattern has different boom height settings). Ground level is the target for preemergence herbicides, while the top of the weeds or cover crop is the target for postemergence sprays.
The manufacturer’s catalog recommends the correct boom height for each type and size of nozzle. Check the catalog for the recommended boom height. Since individual fan nozzles deliver more spray in the middle of the patterns than at the edges, boom height needs to be adjusted so that the patterns overlap. Flat fan patterns should overlap 40% of nozzle spacing, and flooding fan patterns should overlap 50% on the target regardless of the nozzle spacing or spray fan angle.
A simple check is to spray water on a clean concrete or asphalt road, parking lot, etc., and to observe the drying patterns. On a warm sunny day, the water will dry in 2 to 4 minutes. Heavy (wet) streaks under each nozzle indicate that the boom is too low. If the target is not at ground level, check the overlap at ground level and then raise the boom the appropriate amount.
A more sophisticated method is to attach strips of water-sensitive paper to boards laid across the swath width. Spray over the water-sensitive paper at normal operating conditions. The yellow paper will turn blue where each spray drop is deposited. Evaluate the uniformity by observing the portion of the paper target that changes color.
As a rule of thumb, boom height settings less than the manufacturer’s recommendations will result in uneven distribution such as banding or striping. Boom height settings higher than the manufacturer’s recommendations will increase the uniformity, but also increase the potential for spray drift, because of the greater distance between the nozzle and the plant.
10. As a final precaution, be sure to wear protective gloves, goggles and waterproof clothing when cleaning or calibrating sprayers or adding chemicals.

24. Std. Flat Spray Tip

28. Std. TeeJet® 80° flat spray at low pressure
Narrow angle and heavy center

30. XR TeeJet® flat spray tip
Driftable Fine % at 40 psi: XR = 5%
(<150 Microns) XR11004 = 14%

31. XR TeeJet® flat spray at low pressure
Wider angle, large droplets fill pattern

33. Drift Reduction Nozzle Technology
Pre-orifice to create
pressure drop, turbulence
to slow liquid velocity
Venturi effect to produce air-induced, larger droplets

35. Turbo TeeJet® flat spray tip
Driftable Fine % at 40 psi: TT11004 = < 2%
(<150 Microns)

36. Turbo TeeJet®
15-60 psi

37. AI TeeJet™ flat spray tip
Driftable Fine % at 40 psi: AI11004VS = < 1%
(<150 Microns)

38. AI TeeJet™
30-90 psi

39. Std. FloodJet Spray Tip

41. Std. FloodJet®
Heavy Edges

42. Standard FloodJet with heavy edges

43. Turbo FloodJet flat spray tip
Driftable Fine % at 40 psi: TF-4 = < 1%
(<150 Microns)

45. Turbo FloodJet with smoothly tapered pattern

46. Turbo FloodJet®
15-30 psi

48. Turbo TurfJet™ flat spray tip
Driftable Fine % at 40 psi: 1/4TTJ04-VS = < 1%
(<150 Microns)

49. Turbo TurfJet™
30-60 psi

50. XP BoomJet

51. XP BoomJet

52. Benefits
Distribution quality is exceptional

54. Nozzle Wear When do I need to replace my tips? Wear rates depend on:
Tip material (stainless, polymer, ceramic)
Chemicals used
Operating pressure
Care used when cleaning
When measured flow rates are 10% over nominal flow rate it’s time to replace them.

55. Common Spray Tip Materials

56. Spray Tip Wear
New Flat-Fan Nozzle
Worn Nozzle
Improperly Cleaned

57. The Nozzle Compromise
Damaged Nozzles
Worn Nozzles
New Nozzles

59. Calibrate!!!

60. Calibration Formulas
Here is one method for selecting the proper nozzle for the situation.

61. Priority Steps for Calibration
Set Nozzle Spacing (Usually fixed)
Select Gallons per acre
Select Travel Speed
Compute Gallons per nozzle.
Determine pressure required to obtain GPM
Check Droplet Size resulting from pressure and Nozzle GPM.
If droplet size too small, then change nozzle and lower pressure to the appropriate pressure.

62. Example: 25 GPA at 5 MPH, for contact chemicals (flat fan nozzle)
GPA x mph x Nozzle Spacing (inches)
GPM per Nozzle =
5940
GPM per Nozzle = (25 x 5 x 20 inches ) / = GPM
The heart of the strategy for controlling spray drift is to be able to shift the size of spray droplets without recalibrating the sprayer. By computing the desired flow through the nozzle and the satisfactory pressure that will create the right size drops, the pressure can remain constant even though different nozzles with the same hydraulic characteristics are used.
XR11004 will give .421 GPM at 41 psi.

63. Nozzle Choices that will do the Job
At 5 MPH and 25 GPA and 20” spacing
XR11004 will give .421 GPM at 41 psi.
TT will give .421 GPM at 41 psi
AI will give .421 GPM at 41 psi
TF-VS2 will give .421 GPM at 41 psi
Most companies manufacture nozzles that have identical hydraulic characteristics, yet provide different drop sizes. Identical hydraulic characteristics mean for this purpose that for the same pressure, the nozzle will provide the same volume of chemical and water carrier through the nozzle. The TeeJet series nozzles above all provide the same volume through the nozzle at the same pressure, yet the droplet size is different based on nozzle type.

64. Setting the Sprayer Pressure to Desired Level
Add water to sprayer and engage pump
Adjust pressure regulator to desired pressure.
Collect liquid in container for one minute and divide the ounces collected by 128 to get gallons per minute flow from the nozzle.
Readjust pressure to get correct gpm for nozzle.
6. Place one NEW nozzle of the type and size to be used during the spraying on the sprayer boom in the position closest to the pump or the control valves.
7. Add water to the sprayer, if necessary, engage the pump, and adjust the pressure regulator to the desired boom pressure selected from the catalog tables for the nozzle to be used. This nozzle and desired output was determined during the precalibration nozzle selection. Using a measuring container, collect the liquid from the NEW nozzle for one minute. Adjust pressure until the amount collected equals the desired nozzle output in GPM. If your container is calibrated in fluid ounces, divide the amount collected in ounces by 128 to convert to gallons. You have now set the correct sprayer pressure. Replace the new nozzle with the regular sprayer nozzle.

65. Adjusting Pressure On-The-Go to Maintain Constant Application
Automatic pressure control, using radar-based speed.
Manual Pressure Controller
Using an inexpensive manual pressure controller, as the sprayer slows down, the pressure can be reduced by consulting a chart of gallons per acre vs. speed vs. pressure. The pressure is set by the toggle switch until the desired pressure is achieved for the speed traveled.
The automatic control of application rate is set by using a speed signal from a radar sensor on the sprayer or a wheel speed sensor. The type of nozzle and pressure setting is set in the automatic control module and as the speed increases or decreases, the pressure is modulated to maintain a constant application rate across the field. If a global position system is connected to the automatic rate controller, then an application map for the field can be used to regulate pressure and to vary the application rate based on rates listed in the map.

66. A Tool to Control Drift! Nozzle Bodies
We finally get to the heart of the subject of controlling drift and precisely applying the correct chemical or nutrient. The use of nozzle bodies allows multiple nozzles to be made available for changing nozzles in the middle of a field and in the middle of a spray application when wind conditions change and the potential for drift increases.

67. Use of Nozzle Bodies for Drift Reduction
Turbo FloodJet -TF
Air Injection-AI
Turbo TeeJet- TT
Many companies now manufacture nozzles that provide drift control by changing the internal configuration of the nozzle to give much more size consistency to the liquid coming out of the nozzle. Drop size consistency affects the amount of small driftable drops coming out of the nozzle. These “2nd Generation” nozzles are much more effective in reducing spray drift.
Fertilizer- QJ
Extended Range -XR

68. Nozzle Strategy Nozzle GPM Pressure psi Drop Size Wind Condition
XR11004
.420
41 psi
Medium
Low/none
TT11004
Coarse
Low/Med
AI11004
Very Coarse
Moderate to 5 mph
1/4TTJ-04
Extremely Coarse
>5 mph, but must spray
This is an example of a selection of four different nozzles, all operating at the same pressure, and providing the same gallons per minute delivery but the only variable is the size of drops coming out of the nozzle. If these nozzles are installed on a nozzle body, the sprayer does not have to be recalibrated after changing from one nozzle to another. The only difference is the size of drop coming out of the nozzle. This is true “dial-a-drop” drift control!

69. Once the sprayer is calibrated and the rate is controlled… The next step is guidance for swathing control to eliminate skips and overlap.

71. GPS
For Spray Guidance
The most popular use of GPS technology is not for automatically varying the rate of chemical or fertilizer application across the field, but for guiding the sprayer so that skipping and excessive overlapping of spray swaths does not create problems, and foam marking systems can be eliminated. GPS light guidance bars are manufactured by over six different companies, but most work on the principle of a light bar or a computer screen the displays the driving direction and/or the path taken by the sprayer.

72. Cultiva Single Module Guidance System Outback Guidance System
Courtesy of Cultiva, Inc.
Courtesy of RMS, Inc.
Three of the most popular GPS Guidance Systems include the Cultiva system which displays all guidance information in a “3-D type” of steering screen. Additional information on speed and sprayer data is shown at the top right and left corners of the screen.
The Outback System is one of the most popular systems in the United States and comes in two versions. The Outback S system is a light bar system and provides guidance by a steering rose indicating the direction and amount of turning by a rotating hand similar to a standard gage needle – Steer right, or steer left by turning the direction of the indicator hand. The Outback 360 is an add-on module which provides a screen with the path of the machine and the boom width indicated. Skips and overlaps are shown as well as field borders and other hazards.
The Midtech/Spraying guidance system provides primary guidance with a light bar as shown in the illustration. A number of configurations are shown in the following slides as the light bar provides different guidance signals. The SmartPad part of the system is similar to the Outback 360 unit, with the field tracking information shown visually. The touch keys are used to configure the guidance system and change operation characteristics while in the field.
Courtesy of Midtech/TeeJet
Courtesy of Midtech/TeeJet

73. Screen Shots of Guidance System in Operation

74. Typical Lightbar Installation
“On Swath”
Typical Lightbar Installation

75. As day turns to dusk spraying continues

76. Spraying at night Less wind – less spray droplet drift
Higher humidity – less vapor drift
Hazards are marked for avoidance

77. Questions?