Automatic valve with 3/8″ slip lok nozzle union drains water from the mist line after every use to prevent dripping nozzles and calcium build up, extending nozzle life. This drain valve needs 250 PSI to close so it is not recommended for low pressure misting systems. You can add the drain valve in the nylon tubing that transitions from the pump to the mist line. Simply cut the nylon tubing with a tubing cutter and slip the tube into the fitting.