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How does the Butterfly Valves Work?

1. Breaking down the Butterfly Valves

Butterfly valves are the most common type of valve for controlling flow. They are utilizing in almost all industries. Also from chemical plants to pharmaceuticals, from breweries to power plants, from wastewater treatment to desalination. If you are looking for a small valve to control your flow, you can try.  Like gate valves, check valves, globe valves, ball valves, plug valves, diaphragm valves, or needle valves. However, if you are looking for a bigger valve, you can try butterfly valves.

2. How do Butterfly Valves work?

The Butterfly valves are among the most popular types of valve exploy for flow control in the process industries. It is a valve design to control the flow of a fluid by using a disc-shape flap as a valve member. That is rotates from a close to an open position by a hand- or power-driven mechanism. Butterfly valves use to control the flow of liquids, gases, and slurries in the process industries, as well as cooling water systems, HVAC systems, and swimming pool and hot tub systems.

The valve is a balanced design with a relatively large, centrally positioned disc that rotates around a pivot point. Butterfly valves are use in a wide variety of industries. Including the chemical, petrochemical, pharmaceutical, power, food and beverage, pulp and paper, biopharmaceutical, and water treatment industries. Butterfly valves are use in a wide variety of applications, including critical seal-off applications, pressure boosting, and pressure reduction.

3. Butterfly Valve Design

Butterfly valves are similar to ball valves, but they have several advantages. They are small and light, so larger sizes install than with ball valves, reducing the loads on structural supports. Therefore, butterfly valves are particularly advantageous in industrial applications. Also, compare to open-center butterfly valves, double-seated ones leave no dead space through which fluids can flow even when they are completely closed. Butterfly valves are very precise, which makes them advantageous in industrial applications. They are quite reliable and require very little maintenance because of their simple design.

Butterfly Valve

4. Butterfly Valve Disc arrangement

4.1 Concentric Butterfly Valve

The most basic type of butterfly valve is the concentric butterfly valve. That is also knows as a zero offset butterfly valve. The stem passes through the center-line of the disc. That is position in the center of the pipe bore, and the seat is the inner diameter of the body of the valve. The disc and the seat are in continuous contact.

Because it relies on the flexibility of the seat rubber to efficiently seal the flow when close. This zero-offset valve design is also call “Resilient Seated” or “Rubber Seated”. For low pressure ranges, butterfly valves with a concentric design are commonly used. A benefit of concentric butterfly valves is that the media going through them will not come into contact with the body since the seat is constructed as a sleeve or cartridge inside the body.

4.2 Eccentric Butterfly Valve

The stem of Eccentric Butterfly Valves, also kith as High Performance Butterfly Valves, does not pass through the center of the disc but is offset from it according to the categories of double and triple offset valves.

The valve is known as a Single-Offset Butterfly Valve if the stem is located right behind the center-line of the disc. In order to extend the service life of the valve, this design reduces disc contact with the seal before full valve closure. Butterfly valves with a single offset change by those with a double offset and a triple offset.

Butterfly valves with a double offset stem have an additional side offset from the disc. Using this double eccentricity, the rotating disc only rubs against the seat for about one to three degrees.

First offset

The shaft axis is offset from the center-line of the sealing point of the disc.

Second offset

The shaft’s axis is offset from the axis of the valve/pipeline.

Butterfly valves with three offsets are commonly utilize in critical applications and are similar to double offset butterfly valves with one more offset. The third offset is the contact axis of the disc seat. As a result of the conical shape of the seat and the conical ridge of the disc, there is minimal contact before the valve fully closes, allowing the disc to seal against the seat without friction. Butterfly valves with triple offsets are more efficient and wear less easily. The metal seats of triple offset butterfly valves create a bubble-tight shut-off. Butterfly valves can be use at higher temperatures due to their metal seats.

The pressure in the pipeline increases the friction between the disc edge and the seat in high performance butterfly valve designs. Compared to other butterfly valves, these have higher pressure ratings and are less likely to wear out.

5. End Connections of Butterfly Valves

The butterfly valves are generally available with flange ends, lug ends, and wafer type. The flanged ends also come with a double flange option. The lug-type end connection comes in handy when the valve serves as an end point on the pipeline. The wafer type butterfly valves are idle for bidirectional flow.

6. Comparison of Butterfly valve vs others

As we know that Butterfly valves are the quarter turn valve provide quick action similar to the ball valves and plug valves. In comparison to both of these valves, the butterfly valves are cheap and required low maintenance. Whereas we compare to any other type of valve, like gate valve or globe valve, the butterfly valve does not stand for accurate throttling process. Furthermore, in high temperature applications, the butterfly valves also stand with trust and strength. The butterfly valves are the best solution barrier in pipelines. In comparison to any other valve, like the ball valve the butterfly valve controls the viscous materials, too.

7. Butterfly valve Advantages

The Butterfly Valves are non-directional valves that will use for controlling the flow of liquids and gases. Butterfly valves are mostly can see in the petroleum and chemical industries as well as the water and wastewater treatment industry. Its low cost and multiple utilization, butterfly valves are often servicing in residential and commercial applications.
A butterfly valve is a type of quarter-turn valve, which means it can be open and close with a quarter turn. This makes butterfly valves easy to operate and generally more economical than valves with other mechanisms. It can also be operated by a pneumatic cylinder. Butterfly valves come in a variety of sizes and materials. Butterfly valves made of steel for in high-pressure applications. Sizes range from 1/2 inch to 36 inch. Few types of butterfly valves are using in low-pressure applications. Come in sizes ranging from 1/2 inch to 24 inches. For mid-pressure applications. They use cast iron butterfly valves. Available in sizes ranging from 1/2 inch to 12 inches.

Conclusion

The Butterfly valve manufacturers supply their valves widely in the petroleum, chemical, construction, shipbuilding, transportation, electric power, and other industries, widely used for medium or high pressure liquid discharge or liquid medium transmission, or into the gas, steam, liquid-gas media interface, medium of the discharge valve of the valve, discharge valve work is very stable, can be used to prevent the liquid discharge at the interface between the liquid and the discharge of the liquid.

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