The 3/4" FHT flush valve is used for automatic flushing of an individual drip line at the beginning and at the end of each irrigation cycle. When reaching 36 GPH at the start up, the flush valve closes, and when pressure drops below 1 PSI the valve opens. To install the flush valve to a drip system connect the 3/4" FHT flush valve to a 3/4" male hose thread compression fitting (model LF082) or to spin lock fittings (model LF057) automatic end of line flush valves.