An agitator initially mixes liquids, suspensions, and emulsions and keeps them mixed while spraying. Most liquid concentrates, soluble powders, and emulsifiable liquids require little or no agitation once they are in solution. Emulsions and wettable powders, and liquid and dry flowables, on the other hand, separate if not agitated. The return flow coming from the by-pass line of the pressure relief valve cannot provide sufficient agitation. Figure 5 shows different types of agitators.
Mechanical agitators are propellers or paddles mounted on a shaft near the bottom of the tank.
If foaming occurs, reduce agitator speed by changing the drive ratio. Hydraulic agitation is the most common means of agitation used on low pressure boom sprayers. The spray solution in the tank is circulated by returning a portion of the output to the tank and discharging it under pressure through holes drilled in a pipe that runs the entire length of the tank, or through special volume-booster agitator nozzles. If a sparged pipe is used, one jet per foot of tank length is recommended. The holes at teach end of the pipe should be approximately 6 inches from each end of the tank.