Dilution drain valve is a mixing valve for diluting solutions while draining a tank. When water pressure is activated, a unique spool valve design moves forward and aspirates the tank dry. When water pressure is deactivated, a PTFE-coated isolated return spring automatically shuts off the valve. It frees up operator to perform other duties while draining tank. It also cools and dilutes solution while draining. These types of valves can be selected for various dilution rates (2:1 and 6:1 standard)