A ball valve controls the flow of fluid via a spherical disc. The disc has a hole in it such that when this hole is adjusted in line with the pipe, then the flow is opened. When disc is turned such that the hole is blocked, then flow is closed.
The advantage of a ball valve is that it is very durable. The valve can be in the closed position for years without leakage. For this reason, they are superior to globe valves or gate valves. Ball valve are ideally suited for shut-off applications, but does not have fine control over flow.
Typical size of ball valves are from 0.5 cm to 30 cm. The valve material can be either of metal, plastic, or a metallic-ceramic combination. It can also be chrome plated for extra durability.
Some ball valves can take pressures up to 10,000 psi; although typically they are rated for 200 psi. Always check the pressure rating of the valve and select the appropriate one for your application. Ball valves also have a temperature rating. Some can support temperatures up to 200°C.
Therefore, ball valves are used in many industrial applications. Three-way valves, four-way valves, and multi-port ball valves in either L- or T-shaped configurations are commercially available. There are also specialty ball valves such as the safety exhaust/energy lockout ball valve and the forged brass ball valve.