The pressure regulator and gauge are used to control operating pressure and allow excess flow to be by-passed through the regulator back to the tank. A reliable pressure gauge is a required feature on all sprayer systems. The gauge should be located as close to the spray nozzles as practical. Boom control valves and pressure regulator also must be mounted close to the operator, or electrically operated valves can be used for remote control of spray booms and nozzles from the operator's location. Spray booms may be classified as wet or dry types.
Wet booms use the material of the booms as the conduit for the spray liquid.
Pipes, tubes or other rigid material through which the material can pass are utilized. Dry booms have a rigid boom constructed of angle iron, channel iron, pipe or similar material to which hoses and fittings carrying he liquid are attached. The spray material passes through the hoses and not the boom itself, allowing more flexibility in set-up. Booms should be constructed so that boom height is easily adjusted and easily converted to travel position. Hydraulic cylinders make this Job simple on many spray rigs.