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. Size the holes in the agitator manifold so that the pump can maintain the operating pressure when all the nozzles are operating. Generally, for a simple hydraulic jet agitator, a flow of 6 gpm for every 100 gallons of tank capacity is adequate.