If you have a basic knowledge of valves, you are probably familiar with one of the most common valves today: the ball valve. A ball valve is a quarter-turn valve that typically uses a ball with a hole in the center to control flow. These valves are known for their durability and shut-off capability, but not necessarily for their precise control. This section describes when a ball valve can be used as a control valve.
Ball valves are not the best device for controlling flow, but they are widely used because of their economy. Ball valves can be used when precise adjustment or control is not required. For example, maintaining a constant water level in a large tank with an accuracy of a few centimeters is not a problem with a ball valve.
As with any piece of equipment, all process conditions should be considered before selecting a valve. These include product or material, pipe size, and flow rate. If you are trying to manage expensive materials or are concerned about waste, you should not rely on ball valves.
Ball valves are not very accurate because they do not adjust proportionally to the large volume of flow through the open orifice. In addition, there is “play” between the stem and the ball, which prevents accurate control. In addition, the ball valve cannot be adjusted accurately near the “closed” and “open” positions because of the torque required to adjust it.
When precise control is required, valves are more accurate than ball valves. Valves are considered the industry standard for control valves because of their superior flow control, while ball valves are better suited for on/off control without pressure loss.
If you need to control a process with a ball valve, consider different types of ball valves depending on the application. Trunnion or V-port ball valves offer better performance and more precise control options in certain scenarios.
Trunnion-mounted ball valves have additional mechanical ball mountings at the top and bottom. Keyways or keyways are used to connect to the stem to eliminate play between the ball and stem. This allows for better control of orifice constriction and more direct flow.
If you need help selecting the right valve for your application, contact Anix USA engineers. After reading this article, you may want to learn more about using a soft sealed ball valve versus a metal sealed ball valve.