Calibrating Backpack Sprayer Gal. Per 1,000 Sq. Ft.

1) Add a measured amount of water into your sprayer.

2) Spray an area measuring exactly 1,000 sq. ft. Walk at a constant speed as you would during normal operations, holding your nozzle at your normal height.

3) Measure the amount of water left in the sprayer. Subtract this from what you started with. The amount used is the amount sprayed per thousand sq. ft.

4) Increase rates by walking more slowly or using a larger tip. Decrease rates by walking faster or using a smaller tip.

5) For more uniform spray coverage, cover the area twice at half rate, the second pass being at a right angle to your first.

Example: 3 gallons starting, 1 gallon ending.
3 – 1 = 2 gallons per 1,000 sq. ft. being applied.
__gallons start - __gallons end = __gallons per 1,000 sq. ft. (if use 1,000 sq. ft. as your area).
Or if covered an area that was not 1,000 sq. ft.:
(__gallons start - __gallons end) x 1,000 / __sq. ft. covered = __gallons per 1,000 sq. ft.

Calibrating Spray Gun Gallons Per Minute

1) Collect the spray from your gun during one minute of spraying at your normal pressure and tip.

2) Measure the amount of time needed to walk through 1,000 sq. ft.

3) Time needed to cover 1,000 sq. ft. times the amount collected during spraying one minute equals the application rate per 1,000 sq. ft.

4) Adjust application rates by changing pressure, application speed or tip size.

Example: collect 1.0 gallons in 1 minute, taking 2.5 minutes to walk 1,000 sq. ft.

1.0 x 2.5 = 2.5 gallons per 1,000 sq. ft. being applied (if area covered 1,000 sq. ft.)
__gallons per minute x __minutes walking gallons per 1,000 sq. ft.

Or, if covered an area that was not 1,000 sq. ft.:
__gallons per minute x 1,000 / __sq. ft. covered = __gallons per 1,000 sq. ft. applied.