When is a ball valve considered open?

A ball valve is considered open when the hole in the ball aligns with the flow inlet of the valve. In this position, fluid can pass through the valve without obstruction. The design of a ball valve enables it to either allow or restrict flow based on the orientation of the ball, which contains a cylindrical hole that runs through it.

When the ball pivots 90 degrees, the hole shifts from a position where it blocks the flow to one where it allows fluid passage. This pivoting motion is essential for the operation of the valve, but it is the alignment of the hole with the flow path that confirms the valve is indeed open.

The other choices inaccurately describe the nature of a ball valve's operation. When the ball is closed against the flow, it prevents fluid passage, which clearly indicates the valve is not open. The position of the handle being fully extended does not directly determine whether the valve is open; rather, it depends on how the ball is oriented inside the valve body. Understanding these mechanics is crucial in determining the state of the valve reliably.