A ball valve is a form of quarter-turn valve which uses a hollow,
perforated and pivoting ball (called a "floating 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 pivoted 90-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.
Ball valves are durable, performing well after many cycles, and
reliable, closing securely even after long periods of disuse. These
qualities make them an excellent choice for shutoff applications,
where they are often preferred to gates and globe valves, but they
lack their fine control in throttling applications.
The ball valve's ease of operation, repair, and versatility lend it
to extensive industrial use, supporting pressures up to 1000 bar
and temperatures up to 752 °F (500 °C), depending on design and
materials used. Sizes typically range from 0.2 to 48 inches (0.5 cm
to 121 cm). Valve bodies are made of metal, plastic, or metal with
a ceramic; floating balls are often chrome plated for durability.
One disadvantage of a ball valve is that they trap water in the
center cavity while in the closed position. In the event of a
freeze, the sides can crack due to expansion of ice forming. Some
means of insulation or heat tape in this situation will usually
prevent damage.Another option for cold climates is the "freeze
tolerant ball valve". This style of ball valve incorporates a
freeze plug in the side so in the event of a freeze up, the freeze
plug ruptures, (acts as a sacrificial disk), thus making for an
easy repair. Now instead of replacing the whole valve, just screw
in a new freeze plug. This is commonly called freeze plug
A ball valve should not be confused with a "ball-check valve", a
type of check valve that uses a solid ball to prevent undesired
Other types of quarter-turn valves include the butterfly valve and
plug valve and freeze proof ball valve.