Calibrating Your Spray Equipment Script Private Applicator General Farming

Transcription

1 Calibrating Your Spray Equipment In this section of your Private Applicator Training we will discuss the calibration of field sprayers. We will: Look at a number of factors which affect application rates Go through the calibration process in your manual Ask you to work through some calibration examples. slide 1 of 45 Although there are a number of equally effective ways to calibrate a field sprayer, the method we ve chosen is relatively simple yet provides enough information for you to understand the process. This method is different than the method featured in the past. It is not any more difficult than the previous method, but is one of the most common ways to calibrate a field sprayer. Purpose of Calibration First, we might want to understand why we calibrate. We calibrate to ensure that your equipment delivers the correct rate of pesticide and delivers the correct rate uniformly over the target area. Thus, from the very definition, one can see that calibration is more than just mathematical calculations because it involves equipment maintenance as well. Calibrating your equipment provides a great opportunity to assure that it is working properly. slide 2 of 45 It is illegal to use or offer for use pesticide application equipment that is leaking or in disrepair, or which cannot be properly calibrated. But one of the most compelling reason to calibrate is... Purpose of Calibration To prevent errors that can lead to crop injury, loss of money or environmental damage. Also, applying over the maximum labeled rate or over application are off label applications. slide 3 of 45 1 P age

2 Mini Sprayers and Pattern You can think of the nozzles on your sprayer as a group of mini sprayers each one delivering spray across the width of the boom or spray swath. You want each nozzle to apply the same volume of spray mix over the entire distance that the sprayer travels in the field. There are three things that affect spray pattern. 1. Nozzle or boom height too low and you might get gaps between spray bands, too high and you may get excessive overlap or drift. slide 4 of Nozzle angle Nozzles used in agriculture typically come in 80 or 110 degree angles, but other angles can be found. Also, nozzles are often put at a 10 degree angle on the boom. This is so the spray pattern from one nozzle does not interfere with the pattern of the nozzle next to it. 3. Nozzle Spacing How the nozzles are spaced, ten to twenty inches apart, will affect the height you wish to have the boom. Most nozzle manufactures will provide information regarding the optimum boom heights and pressures that their nozzles require. The best choice is also influenced by the product you are applying. Spray Rate There are two variables that most affect overall spray rate. Nozzle flow and travel speed. Let s break these two down further. slide 5 of 45 2 P age

3 Spray Rate Nozzle Flow Rate The nozzle flow rate is affected by your operating pressure and the size of the nozzle opening. Increasing pressure or using a nozzle with a larger opening will increase the flow rate. slide 6 of 45 However, increasing pressure will NOT give you a proportional increase in flow rate. For example, doubling the pressure does not double the flow rate; rather, you must increase the pressure four times to double the flow rate. Therefore, pressure cannot be used to make major changes in spray rate. Keep in mind that operating pressure must be kept within the recommended range for each nozzle type to obtain a uniform spray pattern and to minimize drift. Adjusting pressure is good for small adjustments of flow; however, for larger adjustments consider changing the nozzle. Spray Rate Nozzle Flow Rate Changing the size of the nozzle opening will allow more or less liquid to pass through the nozzle. At this point it might be beneficial to talk a little about nozzles and how they are identified. When a company makes nozzles, they design them to put a certain amount of liquid out over a specified amount of time. Most manufacturers measure the rate of their nozzles in gallons per minute (GPM) A manufacturer s quality assurance will work to be consistent in this output at a specific pressure. slide 7 of 45 In the nozzle example we have shown here the identification number is XR What does this mean? It means that it is an Extended Range, a model name that gives some information about the nozzle. In this case, this nozzle holds its pattern in a extended range of pressures. However, 8003 provides two bits of information also. The first is that this nozzle has an 80 degree pattern angle, which would affect the boom height. The second is that this nozzle will put out 0.3 gallons per minute at 40 psi. The 40 psi is something that would be specified by the manufacturer. Knowing the amount a nozzle will put out in GPM will become important when we discuss the actual calibration of the application equipment. 3 P age

4 Spray Rate Speed of Travel The second variable that affects spray rate is speed. Changing the speed of the application equipment is another way you can make large changes in spray rate. The nice thing about changing speed is that it is a one to one relationship. If you increase your speed times 2, from 5 mph to 10 mph, you will then divide your output by 2, from 20 gallons per acre (GPA) to 10 GPA. Thus can be an easy way to make changes to output. However, speed is often determined by the equipment you are using and the conditions of the location you are spraying. slide 8 of 45 Most application equipment have speedometers of various kinds. However, mechanical slippage and wear and tear that computer systems may not pick up can lead to inconsistencies in speed. It is always a good idea to check speed once in a while to confirm accuracy. Spray Rate Speed of Travel To measure ground speed, stake out a distance between 200 and 800 feet. It is best to do this in conditions similar to your spraying location. Use 200 feet for speeds 5 miles per hour (MPH) or less, 400 feet for speeds 5 to 10 mph and 800 for speeds above 10 mph. Fill the tank with water and drive from one stake to the other then back again, timing both trips. Using the average time in seconds, plug the numbers into the equation. slide 9 of 45 Zero point six eight is a constant that converts feet per seconds into miles per hour. It is important that you use feet and seconds in your measurements when using this equation. If you use any other unit of measurement, such as feet per minutes, then the constant will give you a wrong answer. OK, we have covered the variable that affect spray rate and we have been introduced to a little math to calculate our ground speed. Now, let s move into actually calibrating spray equipment. The 4 Steps to Calibration In the following method of calibration, we propose 4 basic steps to calibrate application equipment for a broadcast application. The first is to determine the required flow rate. slide 10 of 45 4 P age

5 The 4 Steps to Calibration The second is to measure the actual flow rate. This will also determine the uniformity of the flow rate at the same time. Are all the nozzles putting out the same amount at the same rate? In this process, while you are checking actual flow rates you are also checking to see if the nozzles are all putting out at the same rate. You are using a single required flow rate as your goal. slide 11 of 45 The 4 Steps to Calibration Once you have caught from each of the nozzles, if the nozzles are all putting out within five percent of the required flow rate then you can skip to step four. However, if there are problem nozzles or they are all putting out a flow rate that is NOT within 5 percent of the required flow rate then you have to take the third step. The third step is to make any adjustment to achieve the required flow rate. As mentioned previously, achieving the required flow rate will also assure that each nozzle is within 5% error of each other. slide 12 of 45 The 4 Steps to Calibration The fourth step is to determine how much pesticide and water to add to the tank. Now, let s go through each of these steps. slide 13 of 45 5 P age

6 1 st Step Determine Flow Rate The first step in this process is to calculate how much each nozzle should be putting out. This equation is one of the most powerful equations in calibrating spray equipment. MPH is often determined by the spray conditions and the equipment capabilities. The GPA is given by the pesticide label and W stands for the nozzle width in inches. The number 5940 is another constant that converts all the units to gallons per minute. As with the equation for calculating ground speed it is important that the units are consistent in this equation. If your nozzle spacing is in centimeters, then the answer will be wrong. slide 14 of 45 Also note that it is convenient that we are calculating gallons per minute for because that is how most nozzle manufacturers label their nozzles. 1 st Step Determine Flow Rate Let s use this equation in an example. You wish to spray the herbicide Whoop IT. The label says to apply 1 pt/a in 15 to 20 GPA. You wish to travel at 8 MPH and your nozzle spacing is 15 inches. Take the equation and plug in the numbers. The answer is 0.3 gallons per minute. This is your required spray rate for that speed to deliver 15 GPA. slide 15 of 45 2 nd Step Actual Flow Rate To calculate your 5% margin of error simply divide 5% by 100 and times that to your value. In our case we end up with 0.4 fl ounces, giving us a margin of error between 13.4 and 12.2 fluid ounces. A good idea is to collect from all of the nozzles and if any nozzles are off by more than 5% of our required spray rate then replace those nozzles. If the whole boom is off more than 5% then check pressure and the plumbing to assure you are running at the recommended pressure and don t have any plumbing issues, like blockages or corrosion. slide 18 of 45 If we catch within 5% of the required spray rate from each nozzle, the rate is correct and uniform, so we can move on to step four. 6 P age

7 2 nd Step Actual Flow Rate Let s throw a monkey wrench into this scenario. Our required spray rate we calculated is 0.3, but we don t have any 03 nozzles, we only have 02s. In this case we would actually collect 8.5 fl oz in 20 seconds. Our output is greater than 5% error of our required spray rate. When we back calculate 8.5 fluid ounces in 20 seconds we find that we are actually putting out 0.2 GPM. slide 19 of 45 3 rd Step Adjust Flow Rate Changes To achieve our required spray rate we might consider increasing pressure. However, increasing it too much will lead to possibly drift issues. In this case we feel that the change is too great to use pressure to increase our actual spray rate to our required spray rate. It is best that manipulate our speed. slide 20 of 45 3 rd Step Adjust Flow Rate Adjusting speed is a simple way to adjust output. Let s go back to the original equation we used to get our required spray rate. We can manipulate this equation to give us a new speed to travel that will provide us with the required spray rate. slide 22 of 45 7 P age

8 3 rd Step Adjust Flow Rate We have used a little algebraic magic to provide us with a new equation. In this adjusted equation, we have MPH equals 5940 times GPM divided by nozzle width times the GPA we wish to put out at. Plug the numbers in. slide 23 of 45 3 rd Step Adjust Flow Rate When we run the math we find out that if we traveled at 5.3 MPH we would still be putting out 15 GPA with the 0.2 GPM that we caught with the nozzles we are using. Traveling at 5.3 MPH might make for a long day and inefficient if you have many acres to cover. If we kept everything the same, what would our GPA be? NEEDS TO BE REDONE DUE TO ARROR ON ORIGONAL AUDIO slide 24 of 45 3 rd Step Adjust Flow Rate Once again, we can manipulate that equation to provide what GPA we would actually be putting out if we kept everything the same. slide 25 of 45 8 P age

9 1 st Step Determine Flow Rate CHANGES We find after running the math that our actual spray rate of 0.2 GPM would give us a GPA of 10 if we traveled at 8 MPH. If we remember back to the beginning of this example, the product label dictated a GPA of 15 to 20. We are below the spray rate dictated by the label. We are stuck with making adjustments to speed. slide 26 of 45 If our calculations provided a GPA that was in the range provided by the label and there were no efficacy issues connected to this GPA, we might be OK with the output. If you accept a different GPA than you originally planned, remember that this will have an effect on the amount of product in the tank, which leads us to step four. 4 th Step Amount to Add Step 4 in calibrating is to calculate the amount of product that will go into the tank. To do this, there are some things that you must know. First, what is the rate that you wish to apply the product at? This is determined by the label. You need to know your desired spray rate in GPA. We did this in steps 1, 2 and 3. Finally, you need to know the tank capacity and field size. Let s put this into an example. slide 27 of 45 4 th Step Amount to Add In this example we have a 500 gallon tank and we have calibrated our sprayer to deliver 20 GPA. We are going to use 32 fl oz of Glypphoste 41 per acre. How much Glyphosate 41 do you add to the tank? Slide 28 of 45 9 P age

10 4 th Step Amount to Add First calculate the number of acres that can be covered per tank. In our example, a 500 gallon tank applying at 20 GPA, will cover 25 acres. slide 29 of 45 4 th Step Amount to Add Applying to 25 acres at 32 fluid ounce per acre, we simply multiply the number of acres by the product rate. We will be adding 800 fl oz to the tank. This converts to 6 gallons and 2 pints. Because we want a total of 500 gallons of mix we would deduct this from the amount water to put in the tank. Depending on your operation, the measuring capability of your water may not be accurate to the pint, but most can get to the gallon or pretty close. slide 30 of 45 4 th Step Amount to Add to a Partial Tank In this example we are applying only to 15 acres. The GPA is still 20 GPA and this time we are applying 12 fl oz/a of Headline fungicide. How much headline do we add to the tank? slide 31 of P age

11 4 th Step Amount to Add Partial Tank If we are not going to be using the full capacity of the tank then use the acreage that you are going to be spraying multiplied by the gallons per acres, 15 acres multiplied by 20 GPA. In our example, we will be mixing up 300 gallons of mix. slide 32 of 45 4 th Step Amount to Add to a Partial Tank We will use the acres again to calculate the amount of product to add to the tank. In our example 15 multiplied by 12. We will be adding 180 fl oz to our tank, which works out to be one gallon 3.2 pints. In many cases the label recommends some form of adjuvant. slide 33 of 45 4 th Step Adjuvant Rates There are two ways that labels give adjuvant rates. The first is expressed by product per acres. For example 2 pts per acre. Simply multiply by the number of acres and we get 32 pints needed in the tank to apply to 16 acres. slide 34 of 45 The second way in which adjuvant rates are given is as a percentage of the mix, often expressed as v/v or volume to volume. For example if we are mixing 250 gallons and we are going to add 0.25% Nonionic surfactant, we would divide the percentage by 100 and multiply it by the number of gallons we wish to mix. In our example it works out to gallons, which converts to 5 pints. 11 P age

12 Calibrating Your Granular Applicator Now let s take a look at calibrating a granular applicator; specifically, the insecticide hoppers on your corn planter. slide 35 of 45 Granular Applications Ounces Per 1000 ft of Row For this type of granular application, product rates are commonly expressed as ounces per 1,000 ft of row. Insecticide labels also provide a table which converts ounces per 1,000 feet of row to pounds per acre to help you determine the total amount of product to purchase. For example, 8 ounces per 1,000 feet of row at 30 row spacing equals 8.8 pounds per acre. For row spacing not shown in these tables, there is a formula on page 196 of your manual for making those conversions. slide 36 of 45 When doing this type of calibration, it is beneficial to think of each hopper applying to a linear acre. A row spacing of 30 inches, or 2.5 feet, means it takes 17,424 feet of row to equal to 1 acre. 1 st Step Determine Flow Rate To calculate the amount to put down on a 1,000 feet of that linear acre, simply take 1,000 ft times the rate per acre, divided by the linear length of the application for 1 acre. This gives us 8 oz per 1,000 ft. Luckily the label has already done this for us. slide 37 of P age

13 Granular Applications Ounces Per 1000 ft of Row To calibrate, first measure and mark a distance of 1000 feet in the field. The terrain should be similar to that of the area to be treated. Adjust the settings on each unit based on recommendations in the owner s manual or on the granular product label. slide 38 of 45 Fill the hoppers with the product you will be applying, turn the units on, and operate them until all are feeding. Turn them off, disconnect the drop tubes, and attach a container (e.g. plastic bag or jar) to the outlet of each applicator. Drive the measured distance, operating at the speed you intend to use during the application. Granular Applications Ounces per 1000 ft of row As shown here, weigh and record the amount of material collected from each hopper; if necessary be sure to subtract the weight of the container. slide 39 of 45 Granular Application Ounces Per 1000 ft of Row Compare the weight collected from each unit to the acceptable range in output. To calculate the acceptable range in output, multiply the recommended rate of 5 ounces by 5%, or In our example, the acceptable deviation is 0.4 ounce, so each unit should have applied within the range of 7.6 and 8.4 ounces. slide 40 of P age

14 Granular Applications Ounces Per 1000 Ft of Row Hopper units 7 and 8 are outside of the acceptable range and you will need to adjust them and recalibrate. slide 41 of 45 Why Calibrate, I have one of these For those of you who use a rate control system, spray rate is maintained. Speed is also maintained by various mechanisms. You will still need to calculate the amount of product to mix into the tank. Even with rate control technologies it is not a bad policy to check the accuracy of what is actually coming out the nozzle. slide 42 of 45 Why Calibrate I have one of these? Equipment can wear out or be off. Meaning was not set up right in the first place. Agricultural equipment takes a beating in the day to day use. In some cases, the level of precision required for this equipment can falter due to conditions that the equipment has to work in. Much of this equipment depends on mathematical principles that use constants that are either input at the factory or behind the wheel. These inputs can sometimes be entered wrong. slide 43 of 45 Slippage can take precise equipment out of exact working order. Blockage of plumbing or valves can lead to less obvious issues. And it is not always a wise policy to take thinking out of the picture, just because the P age

15 Why not make sure it is working? the machine gave you an answer. slide 44 of 45 slide 45 of P age