What is a Ball Valve
|Materials Used||Types||Salient Features||Uses|
A ball valve, one type of quarter turn valve, is quite literally a ball placed in a passageway through which fluid flows. The ball has a hole through it, by which the valve opens and closes. When the ball is positioned so that the hole runs the same direction as the passageway, the fluid simply flows through it, and the valve is open. The ball can also be positioned so that the hole is perpendicular to the passageway so that the fluid cannot pass through, and the valve is closed. It is controlled from the outside, often with a handle that is turned back and forth to open and close the valve.
The basic version described above is a two-way valve. This type has a single, straight passageway bored through the ball, making two openings: one on each side, an inlet and an outlet. A ball valve can also be a three-way valve if a third hole is bored partially through the ball, until it meets the main hole, forming a T. A three-way valve can shut off one or all of the three passageways it connects.
- Cast Iron
- Ductile iron
- Stainless steel
- Metal alloys
- Ceramic etc.
Parts of ball valves:
- End piece
- Cover ring
- Body seals
- Bolt & nuts
Styles of ball valves:
Ball valves have three general body styles. They are as follows:
- Flanged body
- Top entry
Each of these body styles have specific advantages depending upon the requirements of the given application.
- Full port: This has an over sized ball so that the hole in the ball is of the same size as the pipeline thereby resulting in lower friction loss. The valve is larger and the flow is unrestricted.
- Standard port: This has a smaller ball and hence a smaller port. This is less expensive. Flow through this type of butterfly valve is one pipe size smaller than the valve’s pipe size which results in slightly restricted flow.
- Reduced port: Here the flow through the valve is two pipe sizes smaller than the valve’s pipe size which also results in restricted flow.
Salient features of ball valve:
Ball valves have certain characteristics which make them superior to other valves. They are as follows:
- Positive shut off
- Quick in action
- No lubrication
- Visual on/off indication
- Compact design
- Longer life
- Corrosion resistant
- Low pressure drop
- They are used in situations where tight shut-off is required.
- They are wide duty pipe valves.
- They are able to transfer liquids with suspended solids (slurries), gases, liquids.
- They provide superior ease of operation.
- They can maintain and regulate high volume, high pressure and high temperature flow.
- The ball valve body design permits inspection as well as repair of seats and seals without removing the valves’ body from the line.
- Firesafe ball valves provide effective shut-off during or following a fire or when exposed to excessive temperatures.
- Ball valves are used in gas and oil pipelines.