A ball valve is a straight through flow valve that will allow flow to be stopped in either direction. The design of a ball valve remains consistent among the different types, whereas the types of materials used in construction may differ. A ball valve consists of a round closing element and matching rounded seats that allow for uniform sealing. If the ball valve is in the open position, simply rotate the closing element a quarter-turn and the valve is closed. The type of seat used in the construction of each ball valve type varies due to the valves pressure rating and materials of construction.