There is another common valve that are used in the ships and fire safe protection services that are known as ball valves, which can function with quarter turn. It encloses into a round enclosure and is a straight-through valve with matching rounded seats which can facilitate uniform sealing stress. Since, it is the ball that rotates for opening and closing of the valve, it’s been named as ball valve. If tight shut-off is needed then this kind of valves are used. These valves are wide duty valves and can transfer liquids, gases and liquids with suspended solids too.
Following are its pros and cons. Let us start with its pros:
- It can maintain high pressure, high volume and high temperature flow
- Much better ease of operation
- Long service life and rugged construction
- Can easily function with side loads
- Low cost of maintenance
- Lower cost
- No need of any lubrication
- Seats can be inspected and repaired without removing it from the installed line
Following are few cons of these sanitary valves:
- As it is very difficult to clean these valves and hence it can get contaminated
- Poor throttling characteristics
You can never use them in any food, medicine or bio processing industries as it is not possible to clean so easily. In certain chemical or any other non-sterilized application sometimes, they are used.
How to control
A ball shaped disc is working as its closure element. With quarter turn of the actuator the valve can be opened. As the valve opens the hole in the ball parallel to the flow of liquid opens up and the media is allowed to pass through the valve. When the valve is again closed then the ball is again rotated so that the hole is in perpendicular position to the flow direction and thus the media is blocked.
If you need very fast acting start/stop function then ball valves can be used. As these valves need just 90 degree turn of their handle in order to open or close and hence it is considered as fast-acting valve. Due to its quarter turn operation not only it minimizes the time of operation but also the possibility of leakage due to wear and tear.
If high level of accuracy is not needed then ball valves can be used for throttling service. Due to high velocity flow and pressure, throttling may cause the partially exposed seat to get eroded. Such wearing off can eventually lead to valve leakage. Such leakage can be reduced if the manual ball can be made automatic so that it can move faster in response to any change of signal in the position.