About Ball valve:

A ball valve is a form of quarter-turn valve which uses a hollow, perforated and pivoting
ball to control flow through it. It is open when the ball's hole is in line with the flow and closed when it
is pivoted90-degrees by the valve handle. The handle lies flat in alignment with the flow when open,
and is perpendicular to it when closed, making for easy visual confirmation of the valve's status.

In the case that a ball valve is used for cryogenics or product that may expand inside of the ball, there
is a vent drilled into the upstream side of the valve. This is referred to as a vented ball. Safety is the
number one concern when engineers specify a vented ball.

Technical Standard