The two piece of ball valve are given their name by the nature in which they operate, where an internal ball with a bored through center is rotated to either allow or prevent flow through the valve. Ball Valves are part of the quarter-turn valve family, which means they open or close with a 90 degree turn of the handle. Intended for open and close use only, throttling or controlling the flow of media with a ball valve is not recommended and will damage the ball valve itself.
