# Spray Gun

A handheld spray gun operates off a truck-mounted pump and spray tank. Developing a consistent walking speed, arm motion, and uniform spray pattern are the keys to successful application with a hand-gun sprayer. An overlap of one-half swath width (sprayed band) is needed for uniform coverage of parallel passes. Practice on a paved surface using water until your coverage pattern is even. Then set the pressure of the sprayer following the manufacturer’s guidelines for the pump and nozzle before calibrating the sprayer.

## To calibrate a spray gun

Step 1. — Divide 1,000 square feet by your swath width to determine the distance of the test course

Step 2. — Spray the test course with water using the technique you will use for the application. Begin spraying just before you enter the course.

Step 3. — Record the number of seconds it takes to spray the test course. Do this at least three times to get an average time to use for calibration

Step 4. — Spray into a bucket for the average number of seconds from Step 3. Measure this amount and convert it to gallons.

Step 5. — The amount of water collected is the spray gun output per 1,000 square feet. To determine output per acre, multiply output per 1,000 square feet by 43.56

#### Example

1.   For a swath width of 5 feet, mark a test course that is 200 feet long

(1,000 square feet divided by 5 = 200 ft)

2.   Average time in seconds to spray 200 ft. test course:

77 + 79 + 78 = 234

3.   Gallons sprayed into a bucket in 78 seconds: 5.25

4.   Output = 5.25 gallons per 1,000 sq. ft. or 228.7 gallons per acre (5.25 × 43.56)

Note: If your calibration output is not within 5 percent of the label rate, adjust the nozzle or pressure. Recalibrate until your output comes within 5 percent of the label rate.