Butterfly valves – Types, Benefits & Applications

In every fluid transport system, we often require tools & equipment to control the movement of fluids. These tools or components may come in various forms and functionality. Check valves are one of the most popular fluid control equipment. A butterfly valve is a crucial component in fluid or gas transport systems. Like other valves, butterfly check valves also regulate the flow of liquid or gases within pipelines.

Since the discs used in these valves look like the wings of butterflies, they are called butterfly check valves. Well, this disc can be rotated either parallel or perpendicular to the flow direction. As a result, it allows for precise control over fluid movement. Butterfly check valves may come in various types based on different functionalities. For example, wafer type, lug type, flanged type, and butt weld are noteworthy. Although they have a wide range of benefits, they still have some limitations. We will explore these topics in the following few sections.

What Is a Butterfly Valve?

The definition says that a butterfly check valve is a mechanical device that regulates and controls fluid flow. The structure has a circular disc or plate called the “butterfly.” It is typically mounted on a spindle. The valve normally operates by rotating the disc within the pipe to either allow or restrict the flow of the fluid.

Butterfly check valves can be found in water treatment, HVAC systems, and chemical industries. Therefore, we can realize that butterfly valves offer versatile solutions for fluid control. However, their application is not just limited to simple on/off operations. Butterfly check valves are also prevalent in precise flow modulation.

How Does It Work??

For simplicity, we can divide the working principle of a butterfly valve into two mechanisms. They are the operation mechanism and fluid control mechanism.

As said in the previous section, butterfly check valves typically work through a disk known as a “butterfly.” The actuation mechanism turns the shaft and allows the disc to rotate. In most types, the lever or actuator is used. However, when the valve is fully open, the disk is parallel to the flow. It means that there is an unrestricted fluid flow through the valve. Conversely, in the closed position, the disk is perpendicular, preventing the flow.

You can technically achieve fluid control in a butterfly valve by adjusting between fully open and closed positions. The simplicity of the design offers typically quick response times. It makes them ideal for applications where rapid flow changes are necessary.

Advantages Of Butterfly Valve

Butterfly check valves offer a wide range of benefits. This makes them suitable for use in various industries. Let’s explore more.

1. Compact design: Butterfly valves are known for their compact designs. This makes them space-efficient in various piping systems.
2. Easy to install/remove: Butterfly valves are easy to install/remove. The reason behind this advantage is their design simplicity. Therefore, this equipment enables quick & hassle-free maintenance. Ultimately, it reduces downtime and operational interruptions.
3. Quick Operation: Butterfly valves offer rapid operation. As a result, you can achieve efficient flow control of fluid flow. You know, butterfly valves usually come with a quarter-turn mechanism.
4. Wide varieties: Butterfly valves come in a wide range of materials, sizes, and configurations. As a result, they are adaptable to diverse industrial settings. Therefore, you can actually use them for different fluids, temperatures, and pressures.
5. Versatile: Butterfly check valves offer versatility in terms of applications. Using them, you can handle liquids, gases, and even chemicals.

Limitations over Other Types of Check Valves

Although Butterfly check valves offer a wide range of benefits, They have some limitations. Well, they are typically ineffective for high-pressure throttling applications. Therefore, they are less suitable for uses requiring precise control under high pressure. However, butterfly valves can also work in high-pressure applications. But for that, you may require proper material selections.

Moreover, butterfly check valves may not be suitable for small-diameter piping systems. In such cases, ball valves are widely popular.

Types Of Butterfly Valves

Butterfly check valves usually exhibit a remarkable diversity. Each type is suitable for specific applications. This diversity typically arises from the need to accommodate different requirements. It includes flow conditions, pressure levels, and other operational requirements. The reason behind manufacturing different types is to ensure optimal control & system performance.

We can categorize butterfly valves into seven different types based on two criteria. By considering the kind of connection, we find four types: wafer, lug, butt weld, and flanged type. On the other hand, we can also find three primary types based on geometry: zero, double, and triple offset valves.

Type#1 Wafer Type Butterfly Valves

Wafer type butterfly valves are one of the most popular butterfly valves widely used in many fields. They are characterized by their compact & lightweight construction. Wafer type butterfly valves are thin and wafer-like in appearance. They can snuggly fit between two pipe flanges without the need for additional equipment or a gasket. The structure of this type features a simple but efficient design. They consist of a flat disc mounted on a central shaft.

Pros

1. Wafer type butterfly valves are ideal for use in limited spaces.
2. They are also manufactured to be compatible with either pneumatic or electric actuators.
3. They are easy to install, and their lightweight construction reduces stress on the pipe system.
4. They offer quick operation, making them ideal for frequent use.

Cons

1. Wafer-type butterfly valves are more susceptible to leakage.
2. Unlike lug-type butterfly valves, wafer-type butter valves can be used as pipe ends or end-of-line service.
3. The entire line must be shut down if either side of the valve requires maintenance.

Type#2 Lug Type Butterfly Valve

Lug type butterfly valve is another popular type designed for ease of installation and removal from a pipeline. This type features threaded inserts, known as lugs, on both sides of the valve body. Lug-style butterfly valves are usually composed of ductile iron or steel. The valve flanges have bolt-connecting threaded tapping lugs.

Pros

1. Lug type butterfly valves can be used as pipe engs or end-of-line services.
2. They are highly durable. In addition, they can withstand high pressure & temperature.
3. They also offer various options with varying sizes and customized designs.
4. Compact design, making this type of valve suitable for applications where space is limited

Cons

1. More expensive than other types of butterfly valves.
2. It may not be as versatile as other types of butterfly valves.

Type#3 Flanged Butterfly Valve

As the name implies, this type of butterfly valve is characterized by its attachments to pipes through flanges. It serves as a critical component in fluid control systems, regulating the flow of liquids or gases. Except for the attaching element, the remaining components are similar to wafer and lug type butterfly valves.

Pros

1. Flanged type butterfly valve offers easy installation due to its flange attachment method.
2. The design is compact, making it suitable for applications with limited space.
3. These valves are known for their quick and efficient operation. As a result, it enables swift adjustments in fluid flow.

Cons

1. It may not be suitable for high-pressure applications. A triple-offset butterfly valve can mitigate this problem.

Type#4 Butt Weld Butterfly Valve

The butt weld butterfly valve is a remarkable type of butterfly valve popular. They are distinguished by their welding connection. It means that the is directly welded to the pipeline. Therefore, we can realize that the butt weld butterfly valve ensures a secure & leak-proof connection. Therefore, they are highly suitable for applications where a tight seal is important.

Pros

1. The butt weld butterfly valve ensures a connection that minimizes the risk of leaks.
2. They offer space efficiency.
3. The welded construction enhances durability as well as the efficiency of the control.
4. They are also ideal for high-pressure applications.

Cons

1. Direct welding can pose challenges during maintenance or replacement.
2. In systems with frequent valve changes, the welded design could limit adaptability.

Type#5 Zero Offset Butterfly Valve

These types of butterfly valves are concentric by geometry. Zero offset butterfly valve is a specific subtype within the butterfly valve family. The Zero Offset Butterfly Valve has a unique design with a flexible rubber seat positioned exactly at the center of the valve. This design ensures a smooth and effective control of fluid flow.

Pros

1. Smooth and effective control of fluid flow
2. The concentric design minimizes friction during the operation
3. The use of elastomer enhances the valve’s sealing capability.

Cons

1. When we rotate the valve disc, it comes into contact with the seat. This might cause rubbing and leakage.
2. Since the seat material only includes rubbers, it can handle low-temperature fluids only.

Type#6 Double Offset Butterfly Valves

Double-offset butterfly valves are also popular for their high performance in pipeline systems. Compared to concentric butterfly valves, this type of valve has two stem offsets. One is at the center of the valve, and the other is at the centerline of the valve body. As a result, they offer reduced friction during operation. They also minimize wear & tear on the valve components.

Pros

1. Reduced friction during operation
2. Minimizes wear & tear on the valve components

Cons

1. Since the seat material is elastomeric, seat rubbing can be an issue during abrasive and corrosive applications.

Type#7 Tripple Offset Butterfly Valve

The triple offset butterfly valve is an advanced type. The term “triple offset” refers to the three different offsets present in the valve’s construction. The first offset is positioned at the disc’s centerline. The second is at the shaft with regard to the bore’s centerline. The third is at the axis of the seat cone angle. 

Pros

1. Triple offset butterfly valves provide an uninterrupted sealing surface.
2. They minimize rubbing and wear between the seal and seat.
3. They also offer smooth and more effective fluid flow.

Cons

1. Comparatively expensive than other types of butterfly valves
2. It may not be suitable for high-temperature applications.

Butterfly Valve Vs Ball Valve

Butterfly check valves and ball check valves are both widely popular in fluid control systems. Each of these types are popular due to their unique advantages. One’s limitations can be another’s benefits. Let’s check them out.

Criteria	Butterfly Check valve	Ball Check valve
Design	Disk known as “butterfly wings” rotates to control fluid flow	The spherical ball rotates to control fluid flow
Operation	Quick quarter-turn rotational motion operation	90-degree turn for full operations.
Operating pressure	Popular in moderate and low-pressure applications	Ball valves are commonly used in high-pressure applications
Size and weight	Compact design & lightweight	Generally heavier & bulkier
Leakage	More prone to leakage at high-pressure changes	Ball check valves provide a tight seal even at high-pressure changes.
Cost	Cheaper than ball valves, considering the larger sizes.	Ball check valves are more expensive than butterfly check valves.
Applications	Common in large-diameter systems	Versatile and suitable for various applications

Frequently Asked Questions

Q1. Why use a butterfly valve instead of a gate valve?

Answer: Because butterfly valves are ideal for applications where space is limited. Butterfly valves, unlike gate valves, can throttle or regulate flow and be fully open or closed. In addition, butterfly valves are cheaper than other types compared to large-diameter applications. Plus, they are lighter.

Q2. Which is better, the gate valve or the butterfly valve?

Answer: The right answer depends on the properties of the place of application. A butterfly check valve is lighter, cheaper, and ideal for applications in compact spaces. It offers throttle flow, whereas the gate valve only offers on/off. However, gate valves offer less flow resistance, which makes fluid flow smoother. Therefore, you can get less pressure drop.

Q3. How do you tell if a butterfly valve is open or closed?

Answer: You can visually determine the state of your butterfly valve. In open position, the disc is parallel to the fluid flow. On the other hand, in the closed position, the disc is perpendicular to the flow.

Final Thoughts

Let’s wrap up everything. Butterfly check valves play an important role in a fluid control system. They come with compact designs with a wide range of varieties. It is widely popular in diverse applications. When choosing the right check valve for your applications, it is necessary to evaluate some key points. It may include the diameter of the target application, operating pressure, pressure drops, and budgets.

All check valves may have extensive types and sizes. Even butterfly check valves have seven major types. Therefore, when choosing the right product for your application, it is important to evaluate these key factors. For more information, feel free to contact us.