Module 009 - Sprayer Calibration

8/12/2019 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

Module 009 - Sprayer Calibration

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