Butterfly valves are an important component in many municipal, industrial, and commercial systems, as they are used to control the flow of gasses and liquids. There are several types of butterfly valves, each with its own specific designs and features.
In this article, we will explore the different types of butterfly valves and their uses. Understanding the differences between these valves can help you choose the right one for your specific application, ensuring efficient isolation and effective flow control.
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Wafer Butterfly Valve
The Wafer Butterfly Valve is sandwiched between two flanges, and none of the bolts on the flange will thread into the valve body itself. Wafer butterfly valves provide a low-cost solution for isolation.
There are several options of wafer-style valves, the most common are AWWA C504, API609, and high performance. The wafer style allows for a compact design, making it ideal for applications with limited space.
A wafer-style valve can be a zero, single, double, or triple offset butterfly valve. Among these options, the zero offset valve is the most commonly used and the least expensive. These valves are typically resilient seated, but the double and triple offset valves can be metal seated valves.
Most resilient seated valves can have replaceable seats, but some do not, so make sure you are aware of what type you’re getting as there are benefits to both.
Lug Butterfly Valve
The lug butterfly valve has lugs on the body of the valve, allowing for direct mounting to the pipe without the use of flanges. The counter flange bolts will thread right into the lug-style butterfly valve. Lug butterfly valves provide a low-cost solution for isolation.
There are several options for lug-style valves, and the most common are API609 and high performance. The lug style allows for a compact design, making it ideal for applications with limited space.
A lug-style valve can be a zero, single, double or triple offset butterfly valve, with the zero offset valve being the most commonly used and least expensive. These valves are typically resilient seated, but the double and triple offset valves can be metal seated valves.
If there is a metal seat on your valve, check and see if it’s replaceable and what it takes as far as service to ensure a long life with your valve.
Check out: Av-Tek’s Lug/Wafer Valves
Double Flange Butterfly Valve
The double flange butterfly valve has two flanges on the body of the valve, providing increased stability and security in high-pressure applications.
There are several options of flanged style butterfly valves, the most common are AWWA C504, API609, double offset or also known as double eccentric, high performance, and triple offset.
A flanged-style valve can be a zero, single, double, or triple offset butterfly valve. The zero and single offset are the most commonly used and least expensive.
AWWA C504 is written around single and zero offset valves, but there are some double and triple offset valves that meet that specification. Flanged valves are typically resilient seated. Most resilient seated valves in the flanged world are non-replaceable seats. This means if the valve begins to leak, you will be replacing the whole valve. The double flange refers to the connection to the pipe more than anything else.
This type of butterfly valve is ideal for applications where a tight seal is required, such as water treatment plants or chemical processing facilities.
Check out: Av-Tek’s Double Flanged Industrial Butterfly
Industrial Style High Performance Butterfly Valve
This type of butterfly valve is designed for demanding applications and offers superior flow control. High-performance butterfly valves often have a metal-to-metal seat design and are often used in applications where a tight shutoff is required, such as power plants or pipelines carrying hazardous materials.
One advantage of using this type of butterfly valve is that its seat will outlast a standard resilient seated butterfly valve. Additionally, low torques make these valves easy to operate and extend the life of the actuator.
Notably, tight shut-off is the main reason why users choose an industrial style high-performance butterfly valve. Typically, these valves are made of either carbon steel or stainless steel, which improves their shut-off capabilities.
Av-Tek just launched a High Performance Double Offset wafer butterfly valve, which has PTFE seats and comes in SST or Carbon Steel. Please message us to learn more about this product.
Waterworks Double Eccentric Butterfly Valve
The double eccentric butterfly valve is designed with an offset shaft and disc, providing improved sealing and reduced torque compared to other types of butterfly valves. This type of butterfly valve is often used in applications where a tight shutoff is required and low torque is necessary, such as water pipelines.
Double offset valves have been the standard valve around the world EXCEPT for the U.S. and Canada. Why this is the case is a question we have asked for years.
The double offset butterfly valve does not have issues with compression or seat set on the resilient seat. It has a double overlay weld on the body seat and typically comes with a non-wetted disc hub, among other features.
When we quote our DEX valves in Mexico, Colombia, and Puerto Rico, and the specification is for double offset valves, we scratch our heads wondering why the U.S. is so behind on the technology of butterfly valves. Although double eccentric butterfly valves cost more money, their long-term cost savings are well worth the extra upfront cost.
Check out: Av-Tek’s DEX Double Eccentric Butterfly Valves
Triple Offset Butterfly Valves
Triple offset butterfly valves feature three offsets: an offset between the disc and the stem, an offset between the disc and the seat, and an offset in the sealing surface of the seat.
They are designed to eliminate rubbing between the seat and seal ring through the flow path, which reduces seat and seal wear and extends the valve’s cycle life. The seat of the valve also has a right-angled cone shape due to its offset conical form, which ensures smooth operation throughout the entire cycle.
Triple offset butterfly valves are often used in applications where a metal seat is required and a tight shutoff or quarter-turn actuation is desired, but they can be opened and closed more quickly and can be frequently operated, even in emergency shutoff situations.
With the third offset it makes the valve a torque seated valve rather than a position seated valve.
Conclusion
Butterfly valves are complex mechanisms with a variety of body types and are an important component in manufacturing and industrial processes. It is essential to understand their operation and uses in order to effectively utilize them.
When selecting a butterfly valve, we recommend that you carefully study the application requirements, such as flow rate, pressure, and space constraints, so you can choose the right type of valve for the job.
Butterfly valves are a versatile and cost-effective solution for flow isolation in pipelines. The different types of butterfly valves offer unique features and are designed for specific applications.
The double eccentric butterfly valve is just one example of the many types of butterfly valves but is relatively new to the U.S., but you’ll find with Av-Tek that it is readily available.
At Av-Tek, we’re committed to helping you find valves that bring unprecedented longevity and reliability so you can meet the critical service demands of your organization. If you want to learn more about our products, you can request a quote by filling up this form. Likewise, you may email us at info@avtekvalves.com or call us at (385) 325-2504 or (801) 637-8541.
