Calibrating Spray Equipment

KANSAS CITY, Mo. - Proper calibration of spray equipment is vital to the performance of products used in treated areas.

Published September 04, 2001

KANSAS CITY, Mo. - The following information regarding the proper calibration of spray equipment is provided by PBI/Gordon Corp. Remember to always read the entire pesticide label before using pesticides.

CALIBRATING SPRAY EQUIPMENT

  1. Select the proper equipment for the job to the done. This includes nozzles, pumps, hoses, pressure regulators, etc.


  2. During calibration, only use water and a spray colorant. Do not use pesticide during calibration. The colorant will aid in determining spray pattern, droplet size, coverage and pressure.


  3. Calibrate properly and check calibration periodically.

CALIBRATION OF BACKPACK, HAND CAN SPRAYS AND SHOWER HEAD TYPE "GUNS" (BROADCAST APPLICATION)

Flat fan nozzles and shower head guns are generally used in broadcast applications.

  1. Measure a 20-feet by 50-feet area, or 1,000 square feet.


  2. Fill the sprayer with water and colorant to a known mark.


  3. Spray the 1,000 square feet area.


    • Keep walking speed and pressure constant. Use of the colorant will show light, heavy or skipped areas of application.


  4. Measure the amount of water required to refill the sprayer to the known mark. This is the spray volume per 1,000 square feet.


  5. The amount of pesticide to be added to 1 gallon of water can now be determined using the following formula:

    Label Rate in ounces/1,000 square feet
    Spray Volume in gallons/1,000 square feet    		 = number of ounces of pesticide to be added per gallon of water

    Example 1: The pesticide label rate is 1.2 ounces/1,000 square feet. The spray volume is 0.5 gallons/1,000 square feet.

    1.2
    0.5    		 = 2.4 ounces of pesticide per gallon of water

    Example 2: The pesticide label rate of 1.5 ounces/1,000 square feet. The spray volume is 2 gallons/1,000 square feet.

    1.5
    2    		 = 0.75 ounces of pesticide per gallon of water

CALIBRATION OF BACKPACK AND HAND CAN SPRAYERS (SPOT SPRAYING)

Hollow cone nozzles are generally used in spot spraying. Therefore, these nozzles are difficult to calibrate because the spray pattern is different than flat fan patterns. The dilution of pesticide in water is more important than the area covered in spot spraying.

  1. Fill the spray with water.


  2. Pressurize and spray water into a measured container for one minute. Keep pressure constant.


  3. Measure the amount of water dispensed.


  4. The mixing rate can now be determined.


    • If the spray volume is 1 gallon per minute, use a mid to high range of the dosage recommended on the label per gallon of water.


    • If the spray volume is less than 1 gallon per minute, use a low to mid range label dosage per gallon of water.


    • If the spray volume is greater than 1 gallon per minute use the high range label dosage per gallon of water.


  5. Spray weeds just as you would in broadcast applications. Do not drench weeds.

CALIBRATION OF BOOM SPRAYERS

  1. On level ground, fill the sprayer with water and spray colorant.


  2. Open and close the boom valve quickly.


  3. Measure the width of the spray pattern.


  4. Divide 4,000 by the width of the spray pattern. This number is the length of the calibration area. Example: Boom spray width = 15 feet.


  5. Mark the start and end of the calibration area.


  6. Approach starting mark at a desired spraying speed. Open the boom valve at the start of the area and close it at the end. Keep speed and pressure constant.


    • Observe spray pattern - check for plugged, turned or malfunctioning nozzles.


  7. Return to level ground and measure the amount of water required to refill the sprayer.


  8. Divide this quantity by 4 to determine spray volume per 1,000 square feet.


    • From the pesticide label and the following formula determine how many ounces of product should be added to the tank.

      Quantity of water sprayed
      4      		 = spray volume/1,000 square feet

      Tank capacity
      Spray volume      		 = 1,000s of square feet that will be treated per tankful

      1,000s of square feet X label rate/1,000 = ounces of pesticide to be added per tankful

      Example 1: Tank capacity is 150 gallons; quantity of water sprayed over 4,000 square feet is 18 gallons, label rate is 1.5 ounces/1,000 square feet.

      Spray Volume: 18
      4      		 = 4.5 gallons/1,000 square feet

      Area/Tankful will treat: 150
      4.5      		 = 33, 000 square feet

      33 x 1.5 = 49.5 ounces of pesticide per tankful

      Example 2: Tank Capacity = 250 gallons; Quantity of water sprayed over 4,000 square feet = 16 gallons; Label rate = 1.2 oz./1,000 square feet.

      Spray Volume: 16
      4      		 = 4 gallons/1,000 square feet

      Area/Tankful will treat: 250
      4      		 = 62,500 square feet

      62.5 x 1.2 = 75 ounces of pesticide per tankful

For more information about PBI/Gordon visit the company’s Web site at www.pbigordon.com.

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