Contact Information
971 Coffman Road, Building B
Whitewater, CO 81527

Mailing Address
Department 5087
P.O. Box 20,000
Grand Junction, CO 81502-5001

(970) 255-7121

Refill Method for Boom Sprayer Calibration

Items you will need: measuring tape, flags/paint, bucket, stop watch, measuring container.

  1. Fill the spray tank with water.
  2. Measure the effective spray width of the boom. This is the width covered by the spray at the ground level.
  3. Divide the effective width of the boom into 43,560 (square feet/acre) to determine the distance the sprayer must travel to cover an acre.
  4. Measure and mark this distance on the ground. Since the distance required to spray is usually quite large, the common practice is to reduce the course to a fraction of an acre, i.e. 1/10 or 1/16 of an acre.
  5. Re-fill the spray tank to a known reference line.
  6. Spray the measured distance at a known and constant speed that is repeatable in the field.
  7. Measure carefully the amount of water required to refill the tank to the reference line. It is desirable to make 2 or 3 runs to obtain more accurate calibration. Return the sprayer to exactly the same spot each time.
  8. Multiply the number of gallons required to refill the tank to the previously designated reference line by the reciprocal of the fraction of an acre sprayed (1/10, 1/16, ΒΌ, etc.) to determine the delivery rate in gallons per acre (GPA) at the speed and pressure utilized.

For example: A sprayer with a 20 foot effective spray width is calibrated on 1/10 of an acre and requires 4 gallons of water to refill the tank after the calibration run.

To determine the GPA
43,560/20 ft = 2,178 feet
Linear feet necessary to cover 1/10 of an acre = 218 linear feet
4 gallons to refill times 10 (reciprocal of 1/10) = 40 GPA
You will spray 40 gallons per acre. Divide the GPA into the number of gallons of water you have in your tank and this will give you how many acres a tank will treat.