HAND OR BACK PACK SPRAYER CALIBRATION Accurate calibration not only saves money, but it also improves weed control 1. Mark a square area of 18.5 x 18.5 feet (1/128th of an acre) 2. Fill sprayer half full of water 3. Time your self spraying marked off area 4. Spray into a container marked with ounces for the same amount of time as it took to spray 18.5 x 18.5 area. The number of ounces collected in ounce container is equal to the number of gallons you are spraying per acre (GPA) How much herbicide is added to the tank? 1. Read the herbicide label and determine the amount of herbicide rate you want to use 2. Divide your tank capacity by the Gallons Per Acre (GPA). This tells you how many acres you can spray with one tank from your sprayer. 3. Multiply the amount of herbicide you want to apply in step 1 by the acres that can be sprayed in step 2, this will tell you how much herbicide to add to your tank. Example: You have marked off an area that is 18.5 square feet. You spray the area and it takes you 45 seconds. You spray into an ounce measured container and you collect 64 ounces. Your sprayer is now calibrated to spray 64 gallons of water per acre (64 GPA) You have a (4) gallon backpack sprayer. Divide (4) gallons by (64) GPA 4/64=.0625 Which means your sprayer can spray .0625 or 2723 square feet with one tank full. Remember one acre is 43,560 square feet There for you want to times .0625 by 1 acre (.0625x43,560 = 2723 square feet) You want to use an herbicide where the label calls for a rate of 1 pint per acre and one pint is (16) ounces. So multiply (16) ounces by (.0625) = 1 ounce you would add to the 4 gallon tank. Note/Hint IF you apply 20 gallons per acre and you are using a 4 gallon backpack that equals 1/5 of an acre there for adding 1/5 of the amount of herbicide for 1 acre application.
Your sprayer should be calibrated at the beginning of each spray session
18.5’ x 18.5’
Time______it took to spray marked off area. Number of ounces ______collected in measured container. Gallons Per Acre (GPA) you are spraying______. Your sprayer size divided into (GPA) equals number of acres you can do______.
Liquid conversions 1 gallon = 4 quarts = 8 pints =128 ounces 1 quart = 2 pints = 32 ounces = 4 cups 1 pint = 16 ounces= 2 cups 1 cup = 8 ounces =16 table spoons 1 tablespoon = 3 teaspoons = ½ ounce 1 cubic foot of water = 7.5 gallons = 63 pounds Weight conversions 1 pound = 16 ounces = 454 grams 1 ounce = 28.4 grams Area Size 1 acre = 43,560 square feet