Selecting the Right Butterfly Valve: A Guide
A butterfly valve, also referred to as a flap valve, is a straightforward regulating valve suitable for switching control of low-pressure pipeline media. In a butterfly valve, the closing element, typically a disc, rotates around the valve axis to facilitate opening and closing.
These valves find application in controlling the flow of various fluids, including air, water, steam, corrosive substances, mud, oil products, liquid metals, and radioactive materials. Primarily, they serve the functions of cutting and throttling within pipelines. The opening and closing mechanism of a butterfly valve consists of a disc-shaped butterfly plate that rotates around its own axis inside the valve body to accomplish opening, closing, or adjustment tasks.
The butterfly plate of a butterfly valve is positioned in the diameter direction of the pipeline. Within the cylindrical channel of the valve body, the disc-shaped butterfly plate rotates around the axis, typically within a range of 0° to 90°. When rotated to 90°, the valve reaches full open position.
Butterfly valves are known for their simple structure, compact size, and lightweight design, consisting of only a few components. They can be rapidly opened and closed by a 90° rotation, offering straightforward operation. Additionally, these valves exhibit favorable fluid control characteristics.
In the fully open position, the thickness of the butterfly plate presents the sole resistance to the medium flowing through the valve body. As a result, the pressure drop across the valve is minimal, leading to effective flow control.
Valves equipped with metal seals typically boast a longer lifespan compared to those with elastic seals, albeit achieving complete sealing can pose challenges. Metal seals excel in adapting to higher working temperatures, while elastic seals are constrained by temperature limitations.
When selecting a butterfly valve for flow control, the primary consideration is choosing the appropriate size and type of valve. The structural design of butterfly valves is particularly conducive to the production of large-diameter valves. As a result, butterfly valves find extensive use not only in general industries such as petroleum, gas, chemical, and water treatment but also in the cooling water systems of thermal power plants.
Two commonly used types of butterfly valves are the wafer type and the flange type.
The wafer type butterfly valve is installed between two pipeline flanges using double-headed bolts. It provides a compact and lightweight solution for various applications.
On the other hand, a flange butterfly valve features flanges on both ends, allowing it to be directly connected to the pipeline flange using bolts. This type of valve offers a robust and secure connection for more demanding industrial environments.