module 009 - sprayer calibration
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Fertilizer Applicator Certification TrainingModule 9:
Sprayer Calibration
Virginia Cooperative ExtensionVirginia Department of Agriculture and Consumer Services
Virginia Department of Conservation and Recreation
After module completion one will1) know the importance of calibration.2) understand the strengths and limitationsof applying fertilizer with a sprayer.3) understand the basic steps andcalculations in calibrating a sprayer.4) understand the basic calculations andimportance in measuring and knowingthe area to be treated when applyingproduct with a sprayer.
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Be in the KNOW Know your product
Know what is in the product
Know your equipment
Know your area
Know your speed and pressure
What is calibration?
By definition calibration means to alteror regulate so as to achieve accuracy orconform to a standard
We calibrate spreaders and sprayers toensure that we are accurately delivering aspecific amount of nutrient to a knownarea that conforms to standard nutrientmanagement recommendations.
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What is the importance of
calibration?
A properly calibrated machine
ensures accurate delivery of nutrients,
thereby:
Promoting turf and landscape plant
health
Protecting the environment
Improving the efficiency (in time,
labor, and cost) of the application.
Once calibrated, alwayscalibrated?
No!
Expect sprayer calibrations to change due to:
Equipment operation and/or wear (variances in
pressure, pumps, nozzles, tips, etc.)
Changes in operator or equipment speed
Possible changes in product formulation
Record calibration settings for specific
machines and products
Periodically recalibrate to ensure accurate
delivery
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Sprayer Calibration
Fertilizer delivery by spraysolution typically requiressome basic PersonalProtective Equipment PPE)per label or Material SafetyData Sheet MSDS)requirements specificgloves, long pants or shirtsleeves, specific boots, etc.).If a pesticide is added to thefertilizer solution to besprayed, be sure the PPEselected meets the labelrequirements for thepesticide as well.
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This module will detail the
basic calibration steps for three
spray delivery methods
Single nozzle spray
gun (typical to
professional lawn care
operators) nozzles
usually offer flow rates
of 1.5 to 4 gallons perminute and tanks hold
50 or more gallons of
spray solution
This module will detail thecalibration steps for three spray
delivery methods
Backpack
sprayer
calibration
(typical tomost
homeowners;
3 to 4 gallon
sprayers)
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This module will detail the
calibration steps for three spray
delivery methods Multi-nozzle
boom sprayer
(typically to golf
superintendents
and/or sports
turf managers);
tanks hold 50
gallons or more
of solution.
Advantages of sprayerdelivery:Rapid and uniform
product delivery by
using water as a
carrier
Ability to specifically
direct where product
is being applied (i.e.
keep materials off of
non-targethardscapes and
vegetation)
Ability to mix with a
variety of other liquid
chemical formulations
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Disadvantages of sprayerdelivery:Sprayers have many parts to
select and maintain to
ensure accurateperformance (pumps,
pressure valves, nozzles,
tips)
Wind can affect delivery
Lawn areas must be free of
debris before spraying (in
particular leaves)
Consistent applicator speed
and pump pressure required
for proper deliveryFoliar burn potential?
Tools required for calibrating asprayer
Flags or marking paint
A tape measure to
measure length of course
distance and width of
sprayer pattern or
perhaps nozzle spacing or
boom height
Stop watch
Graduated container for
collecting
Calculator
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Other considerations in fertilizer
delivery by spray systems
Spray pressures
can obviously be
adjusted but are
typically in the
range of 15-45 psi
for most low-
pressure lawn andlandscape
applications.
Other considerations in fertilizerdelivery by spray systems
The output of a sprayer has a direct inverse relationship
to sprayer speed. For instance, doubling the speed
reduces output by ; reducing speed by doubles the
output.
Changing pressure is not quite a direct inverse
relationship as for speed. For instance, to double the flow
rate, pressure must be increased 4x. But in general, aspressure increases, the output also increases, along with
a decrease in droplet size and increased wear on the
sprayer orifices (tips, nozzles etc.).
Be sure to select appropriate nozzles and tips for the
pressure ranges desired for the application.
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Fertilizer sources for sprayapplications
Liquid fertilizer formulations
usually have inherent advantages
in mixing and delivery as most form
spray solutions very quickly.
However, care must be taken
when mixing with other fertilizer
and/or chemical formulations
regarding both physical and
chemical properties.
Consult labels for both fertilizer
and pesticides before mixing and
conduct a jar test to ensure
chemical compatibility
Fertilizer sources for spray applicationsFertilizer Analysis Salt Index >2.5
= high; 2.5 to1=mod;
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Calibrating a spray gunChoose an appropriate spray
pressure suitable for the nozzle
and tip on the spray gunDetermine a suitable spray
swath width with the gun (6 to
10 feet widths waving the wand
from side to side is typical),
planning on making a slight
overlap in spray swath as
product is applied. Also decide
on a calibration length, keeping
in mind that length by width
measurements that total 1000
sq ft make calculations easier.
Establish a consistent and
repeatable walking speed and
apply water over a known
length by width spray course
over a recorded time interval.
A target speed is often 3 mph (or 4.4 feet persecond), but the most important thing is for
the speed of delivery to be constant.
Calibrating a spraygun
Record the time required
to cover the calibration
course.
Collect discharge in a
measuring cup/bucket for
the recorded time period to
determine spray volume per
unit area. (Note: LCOs
typically strive for the
delivery of 1.5 to 2 gallons
of spray solution per 1000
sq ft with spray gun
applications).
Repeat the process until
target delivery rate is
achieved.
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Example Sprayer CalibrationCalculations Spray Gun
If the sprayer width from a spraygun application is 8 feet, howlong (feet) must the calibrationdistance be to cover the desired1000 sq ft in area for thecalibration run?
1000 ft2area desired 8 ftspray swath width = 125 ft incalibration course lengthneeded
Example Sprayer CalibrationCalculations Spray Gun If the goal is to establish a 3 mph walking speed (4.4
ft/second = 3 mph rate), how long will it take to cover the125 foot course length?
125 ft length 4.4 ft/second = approximately 28 seconds.
NOTE: If the applicator calibrates their pace to 28 secondsto cover the 125 ft course length with an 8 ft sprayer swath,then whatever volume of spray they collect over a 28
second period will be the spray volume per 1000 sq ft ofarea. If the target is 2 gallons per 1000 sq ft, then theapplicator will collect 2 gallons of water (or 2 gallons * 128oz/gallon = 256 ounces of water) in the calibration run.
If the targeted volume of spray solution delivery is notachieved, the applicator can alter their speed, the pumppressure, and/or the nozzles/tips for the delivery.
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Another way to calibrate
delivery rate of a spray gun Check flow rate by collecting material from the gun for 1 minute.
Measure the time required to spray 1,000 square feet.
The time required to spray 1,000 square feet x flow rate =
application rate in gallons per 1,000 feet.
Adjust application rates by changing pressure or application
speed.
Example:
1.5 gallons collected from gun for 1 minute
2 minutes required to spray 1,000 square feet
1.5 gallons x 2 minutes = 3.0 gallons per 1,000 square feet application
rate.
As long as application speed and sprayer pressure remain
consistent, the calibration holds.
Spray Gun Calibration CalculationsThe situation. The spray gun iscalibrated to deliver 2 gallons of solution per 1000sq ft. The spraying system is connected to a 100 gallon tank on a truck.
If the goal is deliver lb of N per 1000 sq ft, how much urea will be dissolved in afull tank (100 gallons) of solution for spray applications?
2 gallons : :100 gallons 2(x) = 100(1000) 2x = 100,000) x=50,000 sq ft
1000 sq ft x sq ft
0.5 lb N : : x lb N 0.5(50,000) = 1000(x)25,000= 1000(x)
1000 sq ft 50,000 sq ft
25,000 1000 = 25 lbs N per 1000 sq ft
25 lbs N 0.45 = 55.6 lbs 45-0-0 to be placed in the tank
Fill the tank approximately 1/3rdwith water, add the 55.6 lbs of urea, agitate ifnecessary) and fill the tank to the 100 gallon mark. The sprayer is now calibratedto deliver lb N/1000 sq ft if speed, pressure, etc. remain the same.
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Backpack sprayer calibration As before, establish a
course length,determine swath width(spraying on a road orsidewalk works great)and record the time tocover a known area ofdistance (courselength by spray swathwidth). Course lengthsof at least 50 feet aredesired.
Backpack sprayer calibration If available, use a
pressure regulator toensure constantpressure during theapplication.
While maintaining
constant pressure,capture the dischargefor the same timeduration it took tocover the calibrationarea.
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Backpack Sprayer CalibrationCalculations
The situation. It took 18 seconds to cover a calibration run with a 3 gallonbackpack sprayer over a calibration course using a 3 ft sprayer width and a 100
ft course length. When collecting the spray for the 18 second time period, 50
ounces were collected. What is the volume that the sprayer is calibrated todeliver? How much area square feet) can a full sprayer cover? If the goal is todeliver N at 0.25 lb N/1000 sq feet with ammonium sulfate 20-0-0), how manylbs of 20-0-0 are placed into a full sprayer tank?50 oz : : x fl oz 1000(50) = (300)x 50,000 = 300x x=166.7 fl oz
300 sq ft 1000 sq ft
166.7 fl oz 128 fl oz per gallon = 1.3 gal per 1000 sq ftA 3 gallon sprayer calibrated to deliver 1.3 gal per 1000 sq ft can cover:1.3 gal : : 3 gal 1.3(x) = 1000(3)1.3(x) = 3000 2,308 sq ft1000 sq ft x sq ft
Backpack Sprayer CalibrationCalculationsThe situation. It took 18 seconds to cover a calibration run with a 3 gallonbackpack sprayer over a calibration course using a 3 ft sprayer width and a 100
ft course length. When collecting the spray for the 18 second time period, 50ounces were collected. What is the volume that the sprayer is calibrated to
deliver? How much area (square feet) can a full sprayer cover? If the goal is to
deliver N at 0.25 lb N/1000 sq feet with ammonium sulfate (20-0-0), how manylbs of 20-0-0 are placed into a full sprayer tank?
Since a 3 gallon tank can cover approximately 2,300 sq ft, how much 20-0-0 is
required to deliver the desired N level of 0.25 lb N/1000 sq ft?
0.25 lb N : : x lb N 2300(0.25) = (1000)x575 =1000(x)
1000 sq ft 2300 sq ft
0.58 lb N; 0.58 0.20 = 2.9 lbs 20-0-0Place approximately 1 gallon of water in the sprayer, add the 2.9 lbs of 20-0-0,
stir until fertilizer is dissolved, and fill sprayer to 3 gallons.
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Backpack Sprayer CalibrationCalculations
The situation. Use previous calibration information for the backpack sprayer thatwas determined that a 3 gallon tank can cover 2,300 sq ft. What if one only has
1500 feet of lawn to cover it would not make sense to make up a full tank of
fertilizer solution. So, keeping pressure, speed etc. constant, how much fertilizerand how much spray volume will be placed into the sprayer in order to treat 1500
sq ft of area at a 0.25 lb N/1000 sq ft level using 20-0-0 fertilizer?
0.25 lb N : : x lb N 1500(0.25) = (1000)x375 =1000(x) 0.38 lb N
1000 sq ft 1500 sq ft
0.38 lb N 0.20 = 1.9 lbs 20-0-0 to be placed in the sprayer tank3 gal : : x gal 1500(3) = (2300)x 4500 =2300(x) approx. 2 gal2300 sq ft 1500 sq ft
Place approximately 1 gallon of water in the sprayer, add the 1.9 lbs of 20-0-0,
stir until fertilizer is dissolved, and fill sprayer to 2 gallons and the sprayer is
calibrated to treat 1500 sq ft.
Calibrating a multi nozzle boom sprayerAdditional factors to consider
for calibration in this spray
delivery method are
appropriate nozzle spacing on
the boom to gain proper
overlap of spray pattern AND
an appropriate boom height off
the ground. This information
should be provided in the
operators manual for the spray
system or the users catalog forthe spray nozzles and tips.
Determine the spray pattern
width by multiplying the
distance between nozzles by
the number of nozzles on the
boom, determine a course
length and calculate area as
previously described.
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Calibrating a multi nozzle boom sprayerChecking the spray
pattern of the water on ahardscape (such as a
gravel or concrete
driveway) is a great way to
ensure appropriate spray
overlap (suitable to the tip
selected) and boom
height.
As before, a target
speed is often 3 mph (or
4.4 feet per second), butthe most important thing
is for the speed of delivery
to remain constant.
Boom sprayers are most often used on large
open areas free of trees and/or other
immovable objects.
The Ounce ethod of boom sprayercalibration
Since a gallon equals 128 ounces, if a sprayer is calibrated on an
area measuring 1/128thof an acre (1 A = 43,560 sq ft 128 = 340
sq ft), then the ounces of spray solution captured from one nozzle
during the known time of the calibration run to cover the 340 sq feet
equates to the sprayers delivery on a gallons per acre basis.
Course lengths required to calibrate 1/128th of an acre 340 square feet).Boom nozzle spacing (in.) Course length
12 340
16 255
20 204
24 170
28 146
32 127
36 113
40 102
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The Ounce ethod of boom sprayercalibrationMeasure off therequired course length
according to the uniform
nozzle spacing on the
boom (use table
provided on previous
slide).
Record the time it
takes to travel the entire
course length.
The Ounce ethod of boom sprayercalibration
The spray discharge from one
nozzle captured over the time
required to calibrate the
appropriate course length based
on the nozzle spacing will equal
the sprayers gallons per acre
(GPA) delivery as long as pressure
and speed remain constant.
When possible, collect thedischarge from multiple nozzles
and determine an average nozzle
output in order to compare
numbers and to ensure all
nozzles and tips are performing
similarly AND properly.
As a rule of thumb, if the discharge
from any nozzle/tip exceeds 5% ofthe average nozzle output, that
nozzle/tip should be inspected to
see if there are any blockages, signs
of obvious wear etc., and if so, the
nozzle or tip should be repaired or
replaced.
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Multi-nozzle Boom SprayerCalibration Calculations
The situation. Your goal is to apply N at 0.5 lb N/1000 sq ft using a 20-0-0 watersoluble source. The sprayer is equipped with a 75 gallon tank. The nozzle spacing
is 20 inches and using the information presented in the table on slide 33, the
course length to provide 1/128 thof an acre (340 sq ft) is 204 feet. This length ismeasured. Assuming that the pressure is constant, if the goal is to drive 3 mph
(4.4 feet per second), approximately how long will it take to drive the 204 feetcourse length for the calibration? After determining the time to cover the length,capturing the nozzle discharge for that amount of time results in a collection of30 ounces (i.e. a 30 GPA discharge). How many sq feet can a full sprayer tankcover?4.4 ft : : 204 ft x(4.4) = (204)1 approx. 46 seconds1 sec x sec
30 gal : : 75 gal x(30) = 75(43,560) 30x = 3,267,000; x=108,900 ft243,560 ft2 x ft2
Multi-nozzle Boom SprayerCalibration CalculationsThe situation. Your goal is to apply N at 0.5 lb N/1000 sq ft using a 20-0-0 watersoluble source. The sprayer is equipped with a 75 gallon tank. The nozzle spacing
is 20 inches and using the information presented in the table on slide 33, thecourse length to provide 1/128 thof an acre (340 sq ft) is 204 feet. This length is
measured. Assuming that the pressure is constant, if the goal is to drive 3 mph
(4.4 feet per second), approximately how long will it take to drive the 204 feetcourse length for the calibration? After determining the time to cover the length,
capturing the nozzle discharge for that amount of time results in a collection of30 ounces (i.e. a 30 GPA discharge). How many sq feet can a full sprayer tank
cover? How many pounds of 20-0-0 will be added to the full tank 75 gallons) ifyour goal is to apply 0.5 lb N/1000 sq ft?0.5 lb N 0.20 = 2.5 lbs 20-0-0 per 1000 sq ft2.5 lb fert : : x lb fert108,900(2.5) = x(1000)272,250=1000x 272.25 lbs1000 ft2 108,900 ft2
One would fill the tank approximately 1/3 to 1/2 full of water, add the fertilizer,
stir/agitate, and fill the tank to the final 75 gallon volume.
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Additional strategies for improvingfertilizer delivery by spray systems
There are several toolsthat can be used toeither direct spray or tominimize spray drift.
Spray shields andsprayer skirts are twopossible methods intargeting spraydelivery.
Additional strategies for improvingfertilizer delivery by spray systems
A tracking dye toindicate area coveredby the sprayapplication is picturedhere and these dyesare used with all typesof sprayers.
Foam markers areoften used with boomsprayers.
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r2 r2(AB)*W
L*W
It makes agronomic,environmental, andeconomic sense to knowthe area being treated.
Divide lawns andlandscapes into simplegeometric figures in orderto calculate squarefootage.
GIS technology and smartphone apps?
2
12B*H
Know the area being treated
Additional resources of interest
Grisso, R., P. Hipkins, S. D. Askew, L. Hipkins, and D.
McCall. 2009. Nozzles: Selection and Sizing. Virginia
Cooperative Extension Publication 442-032.
http://pubs.ext.vt.edu/442/442-032/442-032.html.
Grisso, R., M. Weaver, K. Bradley, S. Hagood, and H.
Wilson. 2009. Fine Tuning a Sprayer with Ounce
Calibration Method. Virginia Cooperative
Extension Publication 442-453. http://pubs.
ext.vt.edu/442/442-453/442-453.html.
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Fertilizer Applicator Certification Training
(FACT)
Virginia Cooperative ExtensionVirginia Department of Agriculture and Consumer Services
Virginia Department of Conservation and Recreation
Michael Goatley, Jr.
Professor and Extension Turfgrass Specialist
Crop and Soil Environmental Sciences Department, Virginia Tech
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