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Sprayer Calibration

CALIBRATING A BACKPACK SPRAYER.

What you will need: Measuring tape, Graduated measuring jar, Watch that counts seconds (to help ensure consistent walking speed), calculator, pencil & pad. Accuracy is important here!

  1. Fill the sprayer at least half full with a known amount of WATER.
  2. Spray a pre-measured area (1,000 sq. ft. for example) at the same pace you would in the field. Do not overlap swaths.
  3. Keeping track of how much water you use, refill the sprayer to the known mark. Write down how much water it took to refill the sprayer. This number equals the amount of spray applied per 1,000 sq. ft. 1 gallon = 16 cups.
  4. Repeat these steps two or three times to get an average.
  5. Plug your averaged numbers into the formula.

Label rate in ounces / 1,000 sq. ft. = Number of ounces of pesticide to add per gallon of water / Refill volume in gallons / 1,000 sq. ft.

Course distance
Width In Feet
8” 510’
10” 408’
12” 340’
14” 291’
16” 255’
18” 227’
20” 204’
22” 185’
24” 170’
26” 157’

CALIBRATING YOUR SPRAYER ACCURATELY

  1. In a BROADCAST application, measure the distance, in inches, between two adjacent nozzles.
  2. Locate this width in the table to the right and read off the corresponding course distance.
  3. For more than one nozzle spraying the same area, as with fungicide, measure the band width of one of the nozzles and see no.8 below.
  4. In the field to be sprayed, mark off course of the proper distance.
  5. Tie quart container to one nozzle on the sprayer so as to catch ALL of that nozzle’s spray when sprayer is turned off.
  6. Start a distance back from the beginning of the course to get up to operating speed, and turn sprayer ON at beginning of course and OFF at end.
  7. Remove quart container and read volume collected IN OUNCES.
  8. For more than one nozzle spraying the same area, as with fungicide, multiply ounces collected by number of nozzles spraying the same area.
  9. OUNCES COLLECTED = GALLONS / ACRE