Choosing the correct valve for your application is an important task when designing a process system. Generally, each valve types properties and characteristics make it straight-forward to decide which is best suited for a particular function. However, for specific applications, multiple different valve types may work. Therefore, it is essential to know what type of valve will suit your specific application.

Both butterfly valves and ball valves offer unique benefits, so choosing between them in certain processes isnt a hard choice. It can be problematic when a process requires valve characteristics that both valves have. We need a deeper understanding of the butterfly valve vs ball valve in order to pick the correct valve. 

In terms of operation mechanisms, both valves are arguably the simplest of the valve types available. They are extensively used in domestic, commercial, and industrial applications for flow control of fluids across a wide range of temperatures and pressures. They are quarter-turn rotary (90° turn from fully closed to fully open). Both valve types can be controlled manually, with an electric actuator or with a pneumatic actuator. Butterfly and ball valves are relatively cheap, easy to maintain, reliable, and have a long life expectancy than other valve types.

These similarities do not mean the valves are interchangeable in all process functions. Instead, it suggests and corroborates why we need to take a closer look at the valves characteristics and what applications to use each valve.

About butterfly valve(Click for more details)

A butterfly valve has a disc driven by a lever or handwheel. When closed, the disc is perpendicular to the pipe flow direction. A seal which seats within the valve body ensures a tight closure with the valve disc. A butterfly valves valve characteristics are close to a linear relationship between the flow rate and the stem position. The butterfly valve can be controlled manually, electrically, or pneumatically.

At larger diameters, butterfly valves are generally regarded as cheaper than ball valves. They have the least amount of parts and are relatively lightweight, requiring less support. The weight advantage of butterfly valves to ball valves can be significant at larger pipe diameters. There is a higher probability of leakage at high-pressure differences between the sides of a butterfly valve disc and the seal compared to a ball valve. Also, in applications with large pipe diameters, this high-pressure difference makes it difficult to open the valve, thereby requiring a bypass valve to balance both side's pressure before the valve can be opened.

There is a pressure drop across the butterfly valve as the disc remains inside the flow even when fully open. This hinders using butterfly valves in process streams that need to be pigged, such as in the oil and gas industry. Butterfly valves are typically ON/ OFF valves and are not suitable for precise fluid flow control.

About Ball Valves(Click for more details)

A ball valve has a hollow spherical ball that is pivoted at one or both ends. The top end of the ball is attached to a shaft , which is rotated by a handle to change the valve position to open or close. When fully open, the hole in the ball lies parallel with the pipe flow direction. The ball rests on a seat inside the valve body. The ball valve can be controlled manually, electrically, and pneumatically.

Ball valves can also have three-way or four-way flow directions in a T or L shaped bore. A ball valve’s flow characteristics can be read in our technical article on controlling fluid flow with ball valves.

The bore in a ball valve can vary from a size smaller than the pipe diameter (reduced port or reduced bore), a size equal to the pipe diameter (full port), or a V-port design. The design of the ball does affect flow characteristics. A ball valve can have a pressure drop across the valve in a reduced port ball valve or almost zero pressure drop in a full port ball valve, while a V-port design is ideal for stable flow control.

Unlike butterfly valves, ball valves have zero leakage when fully closed. The fluid pressure upstream of the valve pushes the ball against the seal, ensuring a positive shutoff position. Ball valves will easily open at a high-pressure difference on both sides of the valve and therefore do not require a pressure-balancing bypass.

Advantages and Disadvantages

Though butterfly valves and ball valves share some similarities, they have distinct differences that may have an advantage over the other in specific applications. Below is a comparison showing the valve characteristics of each valve and their advantage against the other.

For more information, please check

Difference Between Gate Valve And Butterfly Valve

Ball Valve vs Gate Valve

Advantages Of Brass Ball Valve

Selection criteria

The following criteria can be considered before selecting between a butterfly valve and a ball valve:

Application: Butterfly valves are commonly used in water-based processes such as sewages, beer and soda production, etc. They are popular in chemical, agricultural, waste treatment plants, and food industries, partly because they are easy to clean. Ball valves can handle both liquid and gases with some solid particles (slurry). They are common in process plants, power plants, petroleum refining, oil, and gas exploration as they can be pigged for cleaning.

Flow capacity: Butterfly valves can provide a larger flow capacity as they are readily available at a larger pipe diameter than a ball valve.

Sealing: Ball valves provide a tight seal in process applications that require zero leakages when shutoff.

Operating condition: Ball valves can operate up to 1,000 bar and 400 degrees Celsius. Butterfly valves typically operate at a lower pressure (less than 50 bar) and temperature (less than 250 degrees Celsius).

Flow regulation: Both valve types can be used for on/off control and proportional control, but ball valves are typically used for proportional due to better flow regulation.

Ports: A butterfly valve can only have two ports, while a ball valve can have more than two ports.

Conclusion

A good understanding of the process requirements and the characteristics of the butterfly valve vs. ball valve helps select the correct valve. Multiple process requirements such as the operating pressure, the accuracy of control, and the type of fluid need to be considered and will define the valve that is best suited. In some applications, both valves may be sufficient, and the choice may be between the cost and maintainability of the valves. In other applications, the pipe diameter may be the only parameter that decides which valve can be used.

FAQ

Which is better: ball valve or butterfly valve?

Butterfly valves typically operate at lower pressures (below 50 bar) and temperatures (below 250 degrees Celsius). Flow regulation: Both valve types can be used for on/off control and proportional control, but ball valves are usually used for proportional control due to better flow regulation.

Why use a butterfly valve?

A butterfly valve is a series of quarter-turn rotary motion valves used to shut off flow in a pipeline. It is often said that butterfly valves can be used to regulate flow. However, we do not recommend this because it can damage the valve disc and negatively affect the sealing performance.

Do butterfly valves restrict flow?

Butterfly valves are used where space is limited. Unlike gate valves, butterfly valves can be used to throttle or regulate flow as well as in the fully open and fully closed positions.

Are butterfly valves suitable for control?

Butterfly valves are a good (and cheaper) alternative to globe and other control valves in applications where 1-2% accuracy is acceptable... High performance butterfly valves are required if pressures and temperatures exceed the limits of the resilient seat.

What is the difference between a globe valve and a butterfly valve?

A globe valve raises the stem when it opens or closes, i.e. the handwheel rotates and lifts with the stem. For butterfly valves, the disc-shaped butterfly plate rotates around its own axis in the valve body to open or close or regulate.

What is the difference between globe valve and gate valve?

The main difference between globe valves and gate valves is the form of internal components and the form of flow inside the two valves. A globe valve has a good throttling ability, while a gate valve is not used for throttling.

Is a gate valve better than a ball valve?

Ball valves are more effective at forming tight seals and offer higher reliability and service life than gate valves, but tend to be more expensive. They are typically used for shutoff and control applications. Because ball valves can be opened and closed immediately, they are more prone to water hammer than gate valves.

Can I use a ball valve instead of a gate valve?

If you already have a gate valve installed and must replace it, you can certainly replace it with a ball valve. You will need a flashlight to heat the parts and remove them. Turn off the water and drain it out of the pipe and valve. You will also need to open the valve.