Valve controlled spraying system

A liquid spraying system (10) for spraying agricultural chemicals comprising:

• a liquid spray section (12) having at least one liquid spray nozzle (14);
• a liquid supply (11) of a liquid agricultural chemical;
• a liquid control valve for controlling the flow of said liquid from said liquid supply (11) to said spray section for discharge from said at least one spray nozzle (14);
• said liquid control valve (15) having a valve body (50, 51) with a liquid supply port (60), a liquid outlet port (65), and a liquid flow back port (66);
• a first liquid supply line (18) for directing said liquid from said liquid supply (11) to said liquid supply port (60);
• a second liquid supply line (19) for directing said liquid from said liquid supply port (60) to said spray section (12);
• a flow back line (20) coupled to said flow back port (66) for directing said liquid in said second liquid supply line (19) away from said spray section (12) upon termination of the supply of liquid to said spray section (12);
• said control valve (15) having a valve stem (70);
• said control valve (15) being operable for moving said valve stem (70) between (1) a first position that opens said liquid supply port (60) for enabling the direction of said liquid from said first liquid supply line (18) through said liquid supply port (60) and liquid outlet port (65) to said second liquid supply line (19) and liquid spray section (12) for discharge from said at least one spray nozzle (12) while blocking flow of said liquid through said flow back port (66) to said flow back line (20), (2) a second position that blocks the supply of liquid from first liquid supply line (18) through said liquid supply port (60) to said liquid outlet port (65) and second liquid supply line (19) while continuing to block the flow of said liquid through said flow back port (66) to said flow back line (20);
• and (3) to a third position wherein during movement to said third position said valve stem (70) continues to block the flow of said liquid from said first liquid supply line (18) through said liquid supply port (60) and liquid outlet port (65) while opening said flow back port (66) for allowing the remaining of said liquid in said second liquid supply line (19) to flow back through said flow back port (66) and flow back line (20) such that the flow of said liquid from said second liquid supply line (19) to said liquid flow back line (20) is only possible when said liquid supply port (60) is closed.