GPM = (GPA x mph x W) / 5,940 (per nozzle)

GPA = (5,940x GPA per nozzle) / (mph x W)

GPM = Gallons Per Minute
GPA = Gallons Per Acre
mph = Miles Per Hour
W = Nozzle spacing (in inches) for broadcast Spraying
    = Spray width (in inches) for single nozzle, band spraying,
       or boomless spraying
    = Row Spacing (in inches) divided by the number of nozzles per row for directed spraying

If the Nozzle on you boom is different than those tabulated, multiply the tabulated GPA coverages by one of the following.

Where tables are Based on 20" Nozzle Spacing:

Where tables are Based on 30" Nozzle Spacing:

Where tables are Based on 40" Nozzle Spacing:

MISCELLANEOUS CONVERSION FACTORS
One Acre = 43,560 square feet = 0.405 Hectare
One Hectare = 2.471 Acres
One Gallon Per Acre = 9.35 Liters per Hectare
One Mile = 5,280 Feet = 1,610 Meters = 1.61 Kilometers
One Gallon = 128 Fluid Ounces = 8 Pints = 4 Quarts
= 3.79 Liters = 0.83 Imperial Gallons
One Pound Per Square Inch = 0.069 Bar = 6.896 Kilopascal
One Miler Per Hour = 1.609 Kilometer Per Hour

SPRAYING SOLUTIONS OTHER THAN WATER
Since all the tabulations are based on spraying water, which weighs 8.34 lbs. per USA gallon, conversion factors must be used when spraying solutions that are heavier or lighter than water. To determine the proper size nozzle for the solution to be sprayed, first multiply the desired GPM or GPA of the solution by the water rate conversion factor. Then use the new converted GPM or GPA rate to select the proper size nozzle.

Example: Desired application rate is 20 GPA of 28% N. Determine the correct nozzle size as follows:

GPA (solution) x Conversion factor = GPA (from table)

20 GPA (28%) x 1/13 = 22.6 GPA (water)

The applicator should choose a nozzled sized that will supply 22.6 GPA of water at the desired pressure.

SPRAY ANGLE & COVERAGE
Depending on the nozzle type and size, the operation pressure can have a significant effect on spray angle and quality of spray distribution. Lowering pressure results in a smaller spray angle and a significant reduction in spray coverage.

Tabulations for spray tips are based on spraying water. Generally, liquids more viscous than water from relatively smaller spray angles, while liquids with surface tensions lower than water will produce wider angles. In situations where the uniformity of spray distribution is important, be careful to operate your spray tips within the proper pressure range. NOTE: Suggested minimum spray heights for broadcast spraying are based upon nozzles spraying water at the rated spray angle.

FLOW RATE
Nozzle flow rate varies with spraying pressure. In general, the relationship between GPM and pressure is as follows:
GPM 1/ GPM 2 = Sq. root psi 1/ Sq. root psi 2
In order to double the flow through a nozzle, the pressure must be increased four times. Higher pressure not only increases the flow rate through a nozzle, but is also influences the droplet size and the rate of orifice wear. As pressure is increased, the droplet size decreases and the rate of orifice wear is increased.