What is the function of bleed valves at the ends of the spray boom?

The function of bleed valves at the ends of the spray boom is primarily to prevent pressure from building up due to trapped air when the spray valve is opened. When the boom is filled with liquid, any air that is present must have a way to escape; otherwise, it could create pressure in the system which might lead to uneven spraying or damage to the spraying equipment.

By allowing trapped air to escape, bleed valves ensure that the spray system operates efficiently and effectively, maintaining consistent pressure and flow during aerial application. This is crucial for achieving accurate application of chemicals, as it minimizes the risk of spray drift and ensures uniform coverage on the targeted area.

The other choices, while addressing different aspects of operation and maintenance, do not accurately describe the primary function of bleed valves. Option A relates to a different method of preventing unwanted spraying from the nozzles, option C concerns maintenance but is unrelated to the operational function of bleed valves, and option D speaks to corrosion but does not capture the essential role that bleed valves play in managing pressure and air within the system.