When you buy a new tool or piece of equipment, it’s great when it is ready to use right out of the box. When it comes to a sprayer for an ATV or UTV, you will have to calibrate the sprayer before you can use it effectively.
If your sprayer is not calibrated you will have no way of knowing how much product you are applying. You could end up applying way too much or way too little. Too much may cause damage and waste money, too little and you won’t have effective results. Therefore it is important to properly calibrate your sprayer before use.
The goal of calibrating an ATV sprayer is to determine the amount of water it takes your sprayer to cover an acre of land. We use an acre because pesticide labels typically provide you with how many ounces per acre of their product to use.
Once you know the number of gallons of water it takes for your sprayer to cover an acre. You can then add the recommended number of ounces for an acre to the amount of water it takes your sprayer to cover an acre.
Before You Calibrate Your Sprayer
The term calibrate may lead people to think this is a complicated process, but it can be quite simple. The key is to make sure that these things are consistent: the speed you travel, the coverage of your boom, your operating pressure, and your spray nozzle size. If one of these things changes then your application rate will change.
If you are unsure about your pressure, speed, nozzle size, or boom coverage, you can jump to this section about how these things will affect sprayer calibration. If you know things are consistent then you are ready to move on to the actual calibration.
Note: If this is a brand-new sprayer, be sure to check for defects before continuing. Manufacturers have been known to miss some things and sprayers can have leaks or missing components. Fill the tank partially full with water and run it to see if there are leaks. Tighten or fix loose connections, and contact the manufacturer if pieces are missing.
Simple Steps to Calibrate Your ATV Sprayer
Step 1: Mark Your Area
Start by measuring and marking off an area to spray for calibration. Because the application rates on pesticides and other products are typically expressed in gallons or ounces per acre, it is easiest to make your test area an acre. This will make the math much simpler.
An acre is 43,560 square feet. If you measure an area 209 feet by 209 feet, you will have just slightly over an acre. If you don’t have that much area, you can calibrate it over a smaller area, like 1/10th of an acre, then do the math to find the gallons it would take to cover a full acre.
Step 2: Spray
Next, you need to fill your tank with 10-20 gallons of water and see how many gallons it takes to cover your marked area. Spray at a constant speed and maintain the same operating pressure. The speed you travel will depend upon your machine and the terrain. For ATVs/UTVs the common operating speed will be between 5-10 mph.
Step 3: Calculate Your Rate
Once you completely spray the area you will know how many gallons of water it takes to spray an acre. Then you can refer to the label on the chemical you will spray. This should provide a per-acre rate of chemical either in ounces or gallons.
For example, it may say 22 ounces per acre. If it took 10 gallons of water to cover an acre, then you would add 22 ounces of chemical for every 10 gallons of water.
Factors that Affect Sprayer Calibration
The coverage of your boom is not the actual length of your boom or the distance between the spray nozzles. It is the effective coverage of the liquid that is coming out of the nozzles. You can figure out your actual boom coverage by spraying water on a driveway, gravel, concrete pad, etc. Anywhere you can get the ground wet and easily see where the boom has covered. Then you simply measure the width of the ground that is wet.
Each nozzle on a spray boom produces a spray pattern of a certain angle, usually 80 or 110 degrees. The spray pattern of your nozzles will overlap to ensure even distribution. “Boomless” nozzles are commonly used with ATV sprayers. They produce a wide pattern that replaces a traditional spray boom with multiple nozzles. The calibration method is the same. For more details view this post about the differences between traditional boom and boomless setups.
As you spray you will also overlap your previous pass to ensure there are no gaps. It is key to maintain a consistent overlap. This can take some practice. The use of a foam marker can help you see where you have sprayed, and help you maintain the same amount of overlap for each pass.
It is important to maintain a constant speed. If you speed up the amount of liquid you apply per acre is reduced. If you slow down, you increase the volume of liquid applied. Pick a speed that is easy for you to maintain and is manageable over the terrain you are covering.
Most ATVs or UTVs have a speedometer, but if you are spraying with a machine that has no speedometer you can attempt to drive the area you will spray at a constant speed. Note the gear or the throttle level. Time how long it takes you to cover the area.
You can do this multiple times to see how consistent you travel. You should do this test with a half-full sprayer tank as this will be the average weight of your sprayer when in use.
When you have done this a few times at a consistent rate, you can use this formula to calculate your actual speed in MPH: (Distance in feet x 60) x (Time in seconds x 88) = MPH
Knowing the actual speed is not as important as being able to travel at a consistent speed over the area you need to spray. However, if you do know your speed you can use it to calculate changes in your application rate as you speed up or slow down.
Like speed, you don’t have to know the exact PSI your sprayer is operating at but you do want the pressure to be consistent. Increasing pressure will increase the flow of liquid through your spray nozzles. This means that if your speed is constant but you increase pressure, your application rate will increase.
So how do you know what pressure to operate at? You should operate your sprayer at a pressure that produces a full and consistent spray pattern from each of your nozzles, but does not result in an extremely fine mist that can drift away from your target area. For more information, you can view this post on sprayer operating pressure.
To calibrate your sprayer you don’t need to know your specific nozzle size. You just need to make sure all the nozzles are the same size. You can read about sprayer nozzles and their effect on application rate in this post.
For a new sprayer, this is pretty easy. Sprayer nozzles are color-coded, so if they are new and all the same color, you can assume they are the same size. If the nozzles are old, you will want to do a “catch test” to make sure that all your nozzles are still going to allow the same flow rate. Nozzles wear out over time, and they don’t always wear evenly.
A “catch test” is simply using a measuring container to collect the output of each nozzle for a certain period of time while the sprayer is running. If your nozzles vary greater than 10 percent in their output, then new nozzles will be needed in order to have consistent application.
When Should You Recalibrate Your Sprayer?
Once your sprayer has been calibrated you can be confident that your application rate will be consistent each time you spray. However, you will need to recalibrate your sprayer if you ever change your nozzle size, nozzle spacing, spray width, speed, or operating pressure.