Wenzhou Unique Valve Co., Ltd.
How does a Ball Valve Work?
Jun 23, 2019
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Ball valves are one of most widely used valves. There is still a growing need for the ball valve. Have you ever wondered how ball valves affect your applications? In this article, you will learn about the common components of a ball valve and their functions. What's more, we will show you how a ball valve works to help you better understand it before you have one for your applications.
What is a Ball Valve?
As its name suggests, the ball valve has a hollow ball that acts as a barrier when the valve is closed. Ball valve manufacturers often design the ball valve to be a quarter-turn valve but it can also be a rotary kind when it controls or diverts the flow of media.
Ball valves are often used in applications that require tight sealing. And they have low-pressure drops. Ball valves are easy to operate even if the media have high volume, high pressure or high temperature. They are quite economical because of their long service life.
Ball valves are suitable for gases or liquids with little particles. These valves don't work well with slurries as the latter easily damages the soft elastomeric seats. While having throttling capacities, ball valves are not used as such because friction from the throttling can easily damage the seats, too.
Parts of a Ball Valve
There are many differences among the ball valves, like 3-way ball valve and the common ball valve in different materials. In fact, 3-way ball valve working mechanism is also different from the common one. There are many ways to classify valves. However, the following seven valve components are common to all valves.
Body
The body is the framework of the entire ball valve. It acts as a barrier to the pressure load from the media so there is no transfer of pressure to the pipes. It holds all the components together. The body is connected to the piping via threaded, bolted or welded joints. Ball valves can be classified according to the type of body, often cast or forged.
What is a Ball Valve?
As its name suggests, the ball valve has a hollow ball that acts as a barrier when the valve is closed. Ball valve manufacturers often design the ball valve to be a quarter-turn valve but it can also be a rotary kind when it controls or diverts the flow of media.
Ball valves are often used in applications that require tight sealing. And they have low-pressure drops. Ball valves are easy to operate even if the media have high volume, high pressure or high temperature. They are quite economical because of their long service life.
Ball valves are suitable for gases or liquids with little particles. These valves don't work well with slurries as the latter easily damages the soft elastomeric seats. While having throttling capacities, ball valves are not used as such because friction from the throttling can easily damage the seats, too.
Parts of a Ball Valve
There are many differences among the ball valves, like 3-way ball valve and the common ball valve in different materials. In fact, 3-way ball valve working mechanism is also different from the common one. There are many ways to classify valves. However, the following seven valve components are common to all valves.
Body
The body is the framework of the entire ball valve. It acts as a barrier to the pressure load from the media so there is no transfer of pressure to the pipes. It holds all the components together. The body is connected to the piping via threaded, bolted or welded joints. Ball valves can be classified according to the type of body, often cast or forged.
Stem
The opening or closing of the valve is provided by the stem. This is also what connects the ball to the lever, handle or actuator. The stem is the one that rotates the ball to open or close the valve.
Packing
This is the gasket that helps seal the bonnet and the stem. Many of the issues happen in this area so proper installation is important. Too loose, leakage happens. Too tight, movement of the stem is restricted.
Bonnet
The bonnet is the lid of the valve opening. This acts as the secondary barrier for pressure. The bonnet is what holds all the internal components together after these are inserted inside the valve body. The bonnet is often made from the same material as the valve body and can either be forged or cast.
Ball
The ball valve uses a hollow ball to control flow through it. The ball is the third most important pressure boundary and thus the pressure of the media acts against the ball when it is in the closed position. The ball is often made of forged steel or any durable material. It can either be suspended like that of the floating ball valve, or it can be mounted like that of the trunnion-mounted ball valve.
Seat
Sometimes, the seat is called the seal ring and it is where the ball rests. Depending on the design of the ball, the seat is either attached to the ball or not.
Actuator
Actuators are devices that create the rotation needed by the ball valve to open the spherical disc. Oftentimes, these have a power source. Some actuators can be remotely controlled so valves still work even if these are located in remote or hard to reach areas.
Actuators can come as handwheels for manually operated ball valves. Some other types of actuators include solenoid, gear, pneumatic and hydraulic types.
How does a Ball Valve Work?
Generally speaking, the ball valve works this way. Whether it is manually or actuator operated, some force needed to turn the lever or handle a quarter turn to open the valve. This force is transferred to the stem, moving the spherical disc to open.
The ball turns and its hole is in line with the flow. At this point, the lever is parallel to the flow. There is a handle stop near the connection between the stem and bonnet to only allow the spherical disc to be pivoted 90-degrees.
The ball valve is closed when it is pivoted to 90-degrees by the lever. The lever is perpendicular to the flow. However, take note that there are three kinds of spherical disc movement. Each of these has different working operations.
The floating ball valve has its ball suspended on the stem. There is no support at the bottom part of the ball.
As the valve closes, the upstream linear pressure from the media pushes the ball towards the downstream cupped seat. This provides a positive valve tightness, adding to its sealing factor. The downstream seat of the floating ball valve carries the load of the internal pressure when the valve is closed.
The other kind is the trunnion mounted ball valve. This has a set of trunnions at the bottom of the ball, making the ball stationary. These trunnions also absorb the force from the pressure load when the valve closes so there is less friction between the ball and the seat. Sealing pressure is performed in both upstream and downstream ports.
When the valve closes, spring-loaded seats move against the ball which only rotates in its own axis. These springs push the seat tightly to the ball. Trunnion mounted ball types are suitable for applications that don't need high pressure to move the ball to the downstream seat.
Lastly, the rising stem ball valve utilizes the tilt & turn mechanism. The ball wedges to the seat when the valve closes. When it opens, the ball tilts to remove itself from the seat and allow media flow.
What is a Ball Valve Used for?
# Oil industries.
# Chlorine Manufacturing.
# Cryogenic systems.
# Cooling water and feed water systems.
# Steam systems.
# Ship flowing systems.
# Fire-safe systems.
# Water filtration systems.
Conclusion
Understanding how the ball valve works means you will know whether these valves are suitable for your needs and make intelligent decisions. If you need to know more about ball valves, please contact UNIQUE.
