Calibrating a Sprayer

Whether you want to use your sprayer for water, weed killer, or crop performance-enhancing applications, it is important to know how to calibrate it.  Calibrating a sprayer allows you to effectively expel whatever you are adding to the soil at the adequate and proper proportions. 

Calibrating a Sprayer

The right calibration also ensures that you don’t run out of whatever material you are expelling mid application. So, to make your task easier the next time you are using a sprayer, below, we’ve outlined a foolproof guide for you on how to calibrate a sprayer.

Tools Needed for Calibrating A Sprayer

The first step is to gather all the tools needed for the process. The required tools for calibrating a sprayer include;

  • A large 30 ounce or more marked pitcher or beaker.
  • Stopwatch or timer.
  • 200 ft. measuring tape or trundle wheel.
  • Soft bristle brush or toothbrush for cleaning nozzles.

How to Calibrate Your Sprayer

Now let’s jump into the actual process. This method for calibrating a sprayer can be used for a wide variety of equipment. This includes an ATV, UTV, 3 point or tow behind sprayer. Following this method ensures that you expel the adequate amount of solution during processes such as boom spraying.

Step 1

Measure the nozzle spacing by calculating the distance between each nozzle to know the travel distance length.

Typically, the nozzle spacing varies between 16 inches and 24 inches. In the distance to travel length, this translates to 255 feet and 170 feet, respectively.

A higher nozzle spacing value equates to less travel distance. So, if the nozzle spacing is 16 inches, the distance to travel will be 255 feet. If the nozzle spacing is 24 inches, the distance to travel will be 170 feet.

Step 2

Measure the appropriate travel distance by a measuring tape or trundle wheel. Mark each point using flag posts.

Step 3

Measure the timed distance by moving the sprayer along the flagged points at the set speed. Time the movement using a timer or stopwatch. Repeat the step at least three times to get an average measurement.

Step 4

After measuring the timed distance, set the correct spraying pressure. Park the sprayer but keep the pump running. Then, set it to the required pressure.

Step 5

 Use the same time as in step 3 to catch the sprayer output in the marked pitcher or beaker to calculate the average output.  You can calculate this value by adding up to 3 different outputs and then, dividing the total measurement.

After this process, clean any nozzle if you need to, to ensure maximum output. You can use a toothbrush or soft bristle brush. As a tip, you should always clean or replace a nozzle if they deliver more than a 10% difference in the output.

Step 6

The next step is to analyze the results from step 5, also known as the average output. The results are measured by ounces. Each ounce capture per nozzle equals the GPA rate. GPA is short for gallons per acre application rate. If the gallons per acre application rate exceeds more than 5% of the intended rate, you may have to readjust the speed and pressure, then, retest the output.

How to Calibrate Your Sprayer

Broadcast Application

In addition to calibrating for regular splaying, you can do this process for other applications. These include broadcast, band, and directed spraying. Boom spraying for broadcast applications refers to applying a solution to the entire area or space.

Step 1

This step involves checking the sprayer for any leaks or damages. To do so, simply fill up its tank with water and run it. If no water spills out, then, it is in perfect working condition.

Step 2

Measure the nozzle spacing distance in inches using a measuring tape. Determine the distance in the field based on the nozzle spacing value. Apply the same procedure as that in the general calibrating method.

Step 3

Run the sprayer at a normal spraying speed and record the time. Do this for at least 2 to 3 rounds to get an average number. Adjust the sprayer to the required pressure whilst the motor is still running.  Catch at least 3 different outputs in the marked pitcher or beaker and then, divide the values to get an average number. 

Step 4

Ensure that each nozzle output doesn’t exceed 10% of the intended value. If not, repeat steps 2 and 3 until you get the ideal range for each nozzle. The final number in ounces equals the application rate. The application rate shouldn’t be more than 5% higher or lower than the intended rate. If not, adjust the spraying speed or pressure and retest the sprayer.

Band Spraying

 Band spraying involves the application of pesticides, herbicides, or other solutions within the crop rows.  Typically, you will follow the same method as you use in broadcast applications. However, the number of pesticides or herbicides added will be less because you will not treat the entire field.

Additionally, instead of using the nozzle spacing value, you will be using the row spacing value with the same travel distance value. For example, a row spacing of 18 inches equals the travel distance of 227 feet. For 20 inches, the distance will be 204 feet.

Because the solution amount is less, the band rate will be lower compared to the broadcast rate as well. For example, a band rate of 15 means that you are using 10-inch bands on 30-inch rows.

Directed Spraying

This process is somewhat similar to calibrating for band applications. It features a row sprayer with two or three nozzles per row. Yet, when compared to regular spraying, calibrating for this particular application is somewhat different.

Regular calibration features a GPA that’s equal to a single nozzle output. Direct spraying on the other end features a GPA that’s equal to a single row. This is because multiple nozzles are used per row. Therefore, the GPA considers the total amount collected from all nozzles directed at a single row.

To compare the actual rate to the rate obtained, you have to do some conversions. You will have to convert the recommended broadcast rate to the band rate. To do so, simply follow the formula:

Band rate = band width (in)/row spacing (in) x broadcast rate.

Best Apps, Calculators, and Worksheets for Calibrating a Sprayer

Sure, you can manually calibrate a sprayer. But as we’ve seen above, the process can be painstakingly long, tiresome, and cumbersome. Therefore, it’s always a good idea to opt for tools to help you with calibrating a sprayer.

You can find a variety of apps, calculators, and worksheets for calibrating a sprayer to make the process easier for you. Below, we’ve listed the best app, calculator, and worksheet that guarantee accurate results.

  • App – the University of South Carolina (downloadable through android or iOS).
  • Calculator – TeeJet (can be downloaded on the official website).
  • Calculator – the University of Missouri (can be downloaded on the official website).
  • Worksheet – the University of Wisconsin (can be downloaded on the official website).
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