Typical field type sprayers consist of spray nozzles, lines, pump, tank, pressure regulator, pressure gauge, strainers, shutoff valve and agitator (Fig. 2). Some sprayers are equipped with pressure activated shutoff valves at each nozzle to stop nozzle flow without dripping. The pump takes the spray material from the tank and pumps it to the spray nozzles. Pressure at the spray nozzles is determined by the setting of the agitator control valve and the pressure regulator, the capacity of the pump and the pressure loss in lines and fittings between the pressure gauge and the nozzles. A portion of the pump discharge is sent back to the tank through the agitator to mix the chemical with the water in the tank.
System components are protected from dirt by tank filler, line and nozzle strainers. The tank filler strainer should be about 20 mesh (20 openings per inch). A line strainer, 50 mesh, should be used ahead of a roller pump to protect the pump. A line strainer may follow a centrifugal pump to protect the nozzles. Strainers may or may not be used at the nozzle, depending on orifice size. Nozzle manufacturers recommend mesh sizes for each nozzle tip.
Some field type sprayers use a boom with nozzles spaced uniformly along the boom (Fig. 3) or on drop pipes for a row crop spraying (Fig. 4). Spray may also be applied in bands directly over the row (Fig. 5)