Ball valve and gate valve are a type of valve, the ball valve is different from the closure of a sphere, the ball around the body centerline of the valve to achieve the opening, closing a valve. Ball valve in the main used to do cut off, distribution and change the direction of the medium flow. Standard GB/T21465-2008 valve - the term "valve term" is defined as: open and close (ball) driven by the stem, and the axis of the valve stem axis for rotary movement.