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 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 and control 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.
A Ball Valve is actually a ball that is placed in the passage where fluids flow. It has a bore through which the valve opens and closes. The fluids easily flow when the hole and the passage way are in the same direction. The valve is closed when the hole is perpendicular to the passage making a closure to the flow of fluids. The closing and opening of the valve is controlled from outside by turning the handle forth and back.
Generally, the balls are made up of combination of various metallic materials while the seats are made up of soft materials. The combination of metallic materials allows the ball valve to operate under all temperature conditions.
There are five different types of Ball Valves based on manufacturing and assembling the pieces of valve –
- Single body ball valve.
- Split body ball valve.
- Welded ball valve.
- Top entry ball valve.
- Three piece body ball valve.