Ball valves are a quick opening valves that give a tight shutoff. When fully open, a ball valve creates little turbulence or resistance to flow.
The valve stem rotates a ball which contains an opening. The ball opening can be positioned in the fully open or fully closed position but must not be used to throttle flow as any abrasive wear to the ball will cause leakage when the valve is closed.
Ball valves are considered high recovery valves, having a low pressure drop and relatively high flow capacity.
Ball Valve Principle, Advantages and Disadvantages
Best Suited Control:
- Quick opening, linear
- Fully open/closed, limited-throttling
- Higher temperature fluids
- Ball valves are excellent in chemical applications, including the most challenging services (e.g. dry chlorine, hydrofluoric acid, oxygen).
- General sizes available are 1/2" to 12".
- Compliant with ASME is the flange rating, either 150, 300, 600, 900# or occasionally higher classes, enabling high performance ball valves to withstand up to 2250 psi.
- The operating temperature which is primarily dependent on seats and seals may be rated as high as 550°F.
- Standard valves comply with ASME face-to-face dimensions, making the ball valve easy to retrofit and replace.
- Low cost
- High flow capacity
- High pressure/temperature capabilities
- Low leakage and maintenance
- Tight sealing with low torque
- Easy quarter turn operation- desirable to most operators
- Fairly easy to automate.
- Limited throttling characteristics
- Prone to cavitation
- Not suitable for slurry applications due to cavities around the ball and seats. Slurries tend to solidify or clog inside the cavities, greatly increasing the operating torque of the valve and in some cases rendering the valve inoperable.