Buying nozzles for your sprayer just got easier. Nozzle manufacturers and crop protection companies are starting to use a new standardized color coding system designed to help reduce spray drift. The color coding matches nozzles and correct droplet size with products. It took eight years, but the industry recently completed the classification system.

The system uses six colors to code droplet size ranging from very fine to extremely coarse (top chart). Nozzle manufacturers classify each nozzle according to the droplet size it produces. Crop protection companies recommend a droplet size for applying their products to minimize drift. (The new color system should not be confused with the ISO flow rate color coding.)

Containing spray

The American Society of Agricultural Engineers (ASAE) led the drive for the classification system. The main purpose for the new system is to address spray containment problems first and product efficacy second. This is different from a spray classification system developed in 1985, which focused on product efficacy.

Rex Guthland, product manager with Hypro, worked with members of the ASAE committee charged with developing the Spray Quality Standard. The committee, which included many of the industry's spray experts, produced a 14-page document labeled ASAE S-572 about how to classify spray.

Growers, fortunately, will not need to read the document. Instead, they simply will match colors between nozzles and products to help ensure proper application.

Convenience

“This is a standard that should make it easier for farmers to switch from one nozzle to another,” Guthland says. “The classification is convenient for labeling and easily referenced in nozzle catalogs. It takes the guesswork out of nozzle selection.”

Guthland notes that the standard classifies nozzles based on droplet size only. The standard does not address discharge trajectory, height and velocity, or other application efficiency factors.

Droplet sizes are compared in the bottom chart on this page. The ASAE standard states that droplet size is usually expressed in microns (micrometers). In addition to how a specific material is sprayed, droplet size also is affected by nozzle style, capacity, spraying pressure and spray pattern type. Lower spraying pressure produces larger droplets, whereas higher spraying pressure creates smaller droplets. Hollow-cone nozzles produce the smallest droplets, and wide-angle, flat-flooding-spray nozzles create the largest spray droplets.

“Fine droplets produce increased efficiency but more drift,” Guthland explains. “Coarser droplets produce less drift but may reduce efficiency.”

Meanwhile, the Environmental Protection Agency is proposing new rules for spraying chemicals that include following the new ASAE S-572 nozzle guidelines. Proposed restrictions for ground boom applications include a nozzle height of no more than 4 ft. above the ground or crop canopy, wind speeds of 10 mph or less at the application site as measured by an anemometer, and use of ASAE S-572-recommended nozzles for the product being applied.

Classification category

Symbol

Color code

Approximate VMD

Very fine

VF

Red

<100

Fine

F

Orange

100-175

Medium

M

Yellow

175-250

Coarse

C

Blue

250-375

Very coarse

VC

Green

375-450

Extremely coarse

XC

White

>450