How Does a Resilient Seated Butterfly Valve Work? - SIO
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How Does a Resilient Seated Butterfly Valve Work?

15/09/2019
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Resilient seated butterfly valves are quarter-turn valves that are used to start, stop, and regulate the flow of materials. A 90-degree rotation of the butterfly valve handle is used to open or close the valve. Unlike gate valves, butterfly valves can be used to regulate the flow of materials. Resilient seated butterfly valves can help to throttle of materials in a fully open and fully closed position. 

Resilient seated butterfly valve
Resilient seated butterfly valve

Butterfly valves are easy to  open and close and are available in small and large sizes. They may be hand-wheel, wrench, or gear operated. There are also electric and motorized butterfly valves available in the market. Read on to find out how resilient butterfly valves are constructed and how they work. 

How is Resilient Seated Butterfly Valve Constructed?

The structure and working mechanism of resilient seated butterfly valve is similar to a ball valve. The valve features a spherical disk with a hole. The hole has a rod running through it that controls the movement of the valve. Resilient seated butterfly valves are also known as concentric valves as the stem is centered in the middle of the valve disk, which in turn is centered in the pipe bore. Here are some of the main components of a butterfly valve.

Diagram of concentric butterfly valve

Source: https://hardhatengineer.com

Body

The body of the resilient butterfly valve houses all other components of the valve. The material of the body depends on the media flowing through it. The most common type of industrial butterfly valves are made of brass, stainless steel, and PVC. Body construction varies depending upon the valve’s function. The two most common body types are lug style butterfly valve and wafer type butterfly valve. The body is constructed using conventional flanged ends or threaded connections to connect to the pipes. 

Seat

The seat of the butterfly valve is where the disk sits. In a resilient or soft seated butterfly valve, the seat is made of rubber and is mechanically attached to the inner wall of the valve body. The seats may be connected to the body of the valve in one of three ways. Dovetail seats feature a male dovetail attached to the body and a corresponding female dovetail seat attached to the seat. This type of seat is suitable for low pressure operations. Cartridge seats have a rigid metal or phenolic resin ring molded inside the rubber seat. These seats can handle higher pressure and vacuum applications. Bonded seats are glued or injection molded to the body of the valve. These seats can handle very high-pressure applications and are the least expensive.

Disk and Stem

In soft seated butterfly valves, the stem and disk are separate pieces that are joined to each other. The disk can float and reposition itself to the seat. The stem passes through the bore in the disk but extends beyond the bottom of the disk to fit into a bushing. This bushing is located at the bottom of the valve body, while one or two other similar bushings are present at the top of the stem as well. 

Actuator

Butterfly valve actuators come in many shapes and sizes. Manual butterfly valves and gear operated butterfly valves use handwheels and gears as actuators. Electric butterfly valves and motorized butterfly valves are operated through buttons and control panels. Butterfly valves with pneumatic actuators and air butterfly valves are more commonly used in the oil and gas industry.

How do Resilient Seated Butterfly Valves Work?

Resilient seated butterfly valves are named so because their inner structure looks like a butterfly with its wings open. It features a rotating disk with a stem passing through its center. The stem looks like the body of a butterfly with one half of the disk on each side looking like its wings. The stem is connected to an actuator or a manual lever that controls the valve. 

Resilient seated butterfly valve
Resilient seated butterfly valve

To open the valve, you have to turn the actuator or lever at 90 degrees. This causes the stem to move which in turn rotates the disk. The disk rotates to become parallel to the flow of the medium, thus allowing unrestricted flow from one end of the pipe to the other. For throttling the medium, you can open the valve partially. The disk won’t be parallel to the pipeline, restricting the flow of the medium. 

Resilient seated butterfly valve
Resilient seated butterfly valve

To close the valve, rotated the actuator again so that the disk becomes perpendicular to the flow of the medium. When this happens the pressure from the onstream will push the rubber seat to the disk forming a firm seal. In resilient seated butterfly valves the seat will come in contact with the disk the earliest (85+/- degrees) during the 90-degree rotation. Thus providing a positive shut-off even at both low and high-pressure applications. 

Applications of Resilient Seated Butterfly Valves

Concentric butterfly valves are the most common type of industrial valves found in the market. They have gained popularity because of their thin profile between flanges, lightweight, and compact design. Furthermore, butterfly valve cost is also less than other types of control valves adding to their appeal. Butterfly valves have a lot of different kinds of applications.

Resilient seated butterfly valve
Resilient seated butterfly valve

Resilient seated butterfly valves may be named after a dainty little insect, but they are anything but that. The valves are strong, durable, and can handle the flow of abrasive materials. Butterfly valves are great for cooling water, air, gasses and more. They can be used to manage the flow of slurry materials. Soft seated butterfly valves can also be used for vacuum services and firefighting. They can easily be used in pharmaceutical, chemical, and food processing services. 

Conclusion

Resilient seated butterfly valves are a cost-effective and durable solution to managing high-temperature, high-pressure piping applications. SIO Resilient Seated Butterfly Valve is made of epoxy coated ductile iron with a self-centering 316 stainless steel disk. Our high-performance butterfly valve features shaft sealing against external leakage and three shaft bushings that support actuation. We can customize the resilient seated butterfly valve to suit your specific needs as well. Reach out to us for more information on how we can help provide full OEM support to your project.

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