what is a butterfly valve used for?
Table of Contents
01 What is a butterfly valve?
Butterfly valves are rotary valves used to stop flow in pipelines. They are common in water systems for their simple, compact design and fast operation.
While butterfly valves can throttle flow, this is not recommended. It can damage the disk and sealing. Butterfly valves are best for on/off duty.
Butterfly valves have a disc that turns 90 degrees to open and close the flowpath. The shaft is offset from the disc center, known as the double eccentric or double offset design.
JHY butterfly valves use the double offset construction. The dual offset of the disc from the rotation axis improves sealing when closed while allowing full flow when open.
02 Butterfly valve components
Butterfly valves have become a staple in various industries due to their simple yet effective design and versatile applications. At the heart of these valves lies a collection of crucial components that work in harmony to regulate fluid flow. Let’s delve into the essential components of butterfly valves and explore their respective functions.
1. Valve Body:
The valve body serves as the structural foundation of the butterfly valve, providing the connection point between the valve and the piping system. It houses the internal components and ensures a secure seal against external pressure. Common valve body designs include flanged, double lug, and wafer types, each catering to specific piping configurations.
2. Disc:
The disc, often referred to as the butterfly, is the heart of the valve’s flow control mechanism. It resembles a rotating gate that pivots within the valve body to open or obstruct the flow path. The disc’s material, orientation, and design significantly impact flow characteristics, sealing effectiveness, and operating torque. For instance, the eccentric disc design reduces seal wear and operating torque.
3. Seat:
A critical component for achieving complete shutoff, the seat is a resilient elastomer or metal seal that lines the internal valve body. It provides a tight seal against the disc in the closed position, preventing fluid leakage. The seat’s material and design play a vital role in resisting corrosion, erosion, and wear.
4. Stem:
The stem, also known as the shaft, acts as the mechanical link between the disc and the actuation mechanism. It transmits the torque required to rotate the disc, thereby regulating fluid flow. The stem’s material and design must withstand the forces exerted during operation and maintain its integrity under various operating conditions.
5. Seals:
Seals are strategically positioned at various interfaces within the valve to prevent leakage and protect internal components from exposure to the process media. They contribute to the valve’s overall reliability and maintainability. For instance, the T-profile resilient sealing ring on the disc ensures a tight seal against the seat, while the multiple O-ring shaft sealing system protects the stem from corrosion and wear.
6. Additional Components:
While not as prominent as the primary components, several smaller parts play crucial roles in the butterfly valve’s functionality. Bushings, bearings, and fasteners provide structural support, minimize friction, and ensure secure assembly. These components contribute to the valve’s overall performance and longevity.
Butterfly valves rely on a harmonious interplay of various components to effectively regulate fluid flow. Understanding the function and design of these components is essential for selecting and maintaining butterfly valves in various industrial applications.
Butterfly Valve Top Flange
A butterfly valve top flange is a circular metal plate attached to the top of a butterfly valve. It's used to connect the valve to other pipes or equipment using bolts or studs.
Butterfly Valve V-sealing
V-sealing in butterfly valves refers to a specific design of the valve disc and seat that provides a tight and reliable seal.
Butterfly Valve Bearing
Butterfly valves rely on bearings to support the shaft that the disc is mounted on, enabling smooth operation and reducing friction.
Valve Stem
A butterfly valve stem is a crucial component that connects the valve handle or actuator to the disc, allowing you to control the flow of fluid through the valve.
Valve Disc
The butterfly valve disc is the central moving component responsible for regulating flow within the valve.
Valve Body
The butterfly valve body is the heart of the valve, housing all the internal components and providing the structure for fluid flow control.
Valve Seat
A butterfly valve seat is a device used in a butterfly valve to provide a tight seal when the valve is closed. It is typically made of a soft material, such as rubber or elastomer, and is located in the valve body.
Locator Holes
Locator holes are used for convenient and accurate installation.
Parts of a Butterfly Valve (with Diagram)
To visualize the internal structure of the valve, a butterfly valve diagram is often requested by users. Above is a typical configuration:
This illustration helps customers and engineers identify each part for installation or maintenance purposes.
03 how does a butterfly valve work?
A butterfly valve operates through a simple yet efficient mechanism: a circular disc mounted on a rotating shaft. When the handle or actuator turns the shaft, the disc rotates to either block, partially allow, or fully permit flow through the pipe. In the open position, the disc is parallel to the flow direction, offering minimal resistance. Turning the disc perpendicular to the flow path closes the valve and blocks fluid passage.
One of the key applications is butterfly valve isolation, where the valve provides a tight shut-off to isolate sections of a pipeline for maintenance or emergency shutdowns. In such cases, a flange butterfly valve is commonly used because of its strong sealing performance and compatibility with flange-mounted piping systems.
In addition to isolation, many industries also use the butterfly valve for flow control. Although it is not ideal for precise throttling like globe valves, it offers an economical and compact solution for regulating flow in large-diameter systems.
Butterfly valves come in a wide range of sizes. The available butterfly valve size typically ranges from DN50 to DN2000, depending on the manufacturer and application. This makes them suitable for everything from residential water systems to large-scale industrial pipelines.
04 Types of butterfly valves
- Wafer type – This is the most basic type of butterfly valve. It consists of a valve body and a disc attached to a shaft. The valve is designed to be sandwiched between two pipe flanges or fittings. Wafer butterfly valves are lightweight, simple, and inexpensive.
- Lug type – This type has extended flanges (lugs) on both sides of the valve body. The lugs have holes for bolting the valve to flanged pipe fittings. Lug butterfly valves provide a sturdier connection than wafer types. They are also easier to install and replace.
- Double flanged butterfly valve – As the name suggests, this butterfly valve has two integral flanges, one on each side of the valve body. The flanges allow the valve to be bolted directly to flanged fittings without having to be sandwiched between them. Double flanged butterfly valves provide a more compact installation but are heavier and more expensive.
- Double eccentric butterfly valve – The double-eccentric type of butterfly valve refers to a design where the disc is offset from the centerline of the valve body and shaft. This offset allows the disc to completely disengage from the seat when the valve is fully open. This design feature helps reduce wear and improves sealing performance.
05 What is the main advantage of a butterfly valve?
- Compact Design: Butterfly valves have a compact and lightweight design compared to other types of valves, such as ball valves or gate valves. This compact design makes them easy to install and maintain, even in tight spaces.
- Low Pressure Drop: Butterfly valves offer low pressure drop, which means they have minimal resistance to fluid flow. This low pressure drop results in energy savings and reduced pumping costs.
- Bi-directional Flow: Butterfly valves can handle fluid flow in both directions, making them versatile for various applications. This bi-directional flow capability eliminates the need for check valves, simplifying piping systems.
- Tight Shutoff: Butterfly valves provide tight shutoff, ensuring complete isolation of fluid flow when closed. This tight shutoff capability is critical for applications where preventing leaks is essential.
- Quick Operation: Butterfly valves can be opened and closed quickly, making them suitable for applications requiring rapid flow control.
- Easy Maintenance: Butterfly valves are relatively easy to maintain, requiring minimal downtime and maintenance costs. The simple design and fewer moving parts contribute to their ease of maintenance.
- Wide Range of Materials: Butterfly valves are available in a wide range of materials, including stainless steel, ductile iron, and PVC, making them suitable for various applications and fluids.
- Cost-effective: Butterfly valves are generally more cost-effective than other types of valves, making them an attractive option for many applications.
- Variety of Actuation Options: Butterfly valves can be actuated using various methods, including manual, electric, pneumatic, and hydraulic actuation, providing flexibility for different applications and control requirements.
06 Why Choose XHY Group as Your Butterfly Valve Supplier?
Xhy Group is one of the leading butterfly valve suppliers in China. With decades of manufacturing experience and ISO-certified production lines, we supply valves for water treatment, fire systems, chemical pipelines, and more.
What sets us apart:
Reliable OEM and ODM services
Full range of butterfly valve components
High-performance materials and precision machining
Timely delivery and responsive support
07 Conclusion
Whether you’re trying to understand what a butterfly valve is, compare types of butterfly valves, or find a reliable double eccentric butterfly valve supplier, this guide provides everything you need. From detailed butterfly valve parts to flanged connection options, XHY Group delivers dependable products for global clients.
Browse our complete butterfly valve catalog or contact us for technical consultation.
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