Sprayer calibration Maury Craig, IR-4 Program Coordinator Extension Plant Sciences Dept. New Mexico State University

Why calibrate my sprayer? Over application, under application, spray drift Legal Safety Environmental effects Waste time, product and money Many ways to make an accurate calibration: Use the one you’re most comfortable with.

Accurate sprayer application is based on four variables 1. Application rate 2. Nozzle flow rate (discharge rate) 3. Sprayer speed 4. Effective spray width In almost every case, changing a variable will change the final sprayer calibration

1. Application rate Amount of tank mix applied per unit area –GPA –Gallons/1000 sq. ft. Low app. rate maximizes treated acreage per tank of mix, high rate offers better penetration of canopy Determining application rate: product label will give GPA range recommendation

2. Nozzle flow rate (discharge rate) The amount of mix delivered through the nozzle per unit time (Gallons per minute, ounces per second) Flow rate is dependent upon two other variables –Nozzle type and capacity Change tip capacity = large-scale discharge change –Line pressure Change pressure = small-scale discharge change Determining flow rate: –Collect and measure timed discharge from each nozzle –Data tables from nozzle mfg.

Nozzles Proper nozzle selection and maintenance are crucial to an accurate application Calibrate nozzles to ensure accuracy. –Collect and measure timed discharge from each nozzle. –Replace a tip if difference is >10% discharge rate of new tip –Replace all tips in boom if several tips are off Clean nozzles and strainers after each use –Use only bristle brush or toothpick to clean orifice

Nozzle nomenclature

Nozzle selection and pressure affect spray drift To decrease spray drift –Use drift-reducing nozzles –Use larger capacity tips (04 vs. 02) –Use lower spray angle tips (80º vs. 110º) –Lower spray boom –Reduce line pressure (30 PSI vs. 50 PSI) Larger capacity tips and lower pressure have the greatest effect

3. Sprayer speed The rate of travel per unit time (MPH, FPS) Determining speed: divide units of distance by units of time –Record range/gear/RPM for tractor sprayer –Use metronome to set pace for backpack application Calibrate speed under load Track surface should be similar to field surface

4. Effective spray width Flat fan boom sprayer –Nozzle spray width = nozzle spacing –Keep boom at proper height above target Boomless sprayer, single nozzle wand, or banded (even fan) applications –Spray width depends on nozzle type or desired band width –Measure spray width or use nozzle mfg. recommendation

Sprayer calibration using TeeJet® technical tables TeeJet Catalog (tech manual) Address Spraying Systems Company P.O. Box 7900 Wheaton, Illinois Website: (supplies more information than the manual)

TeeJet® calibrationcalculator Online use only: requires internet connection to use Will calibrate for any of the 4 variables Requires that you know the other 3 variables.

We want 6 mph sprayer speed and the label calls for a minimum of 20 GPA. Our nozzle spacing is 20 inches. The calculated flow rate is 0.4 GPM, so we will choose a nozzle and pressure combination that provides ~0.4 GPM

Calibration program for use with your computer SprayCal: free program available online Chemical/Index.htmlhttp://agsafety.tamu.edu/Programs/Ag- Chemical/Index.html Sprayzip.exe is under “Computer Software” near bottom of page. –Download program to computer –Also calculates tank mix

Norgren mini inline pressure regulator with gauge –Source: R & D Sprayers P.O. Box 267 Opelousas, LA