The butterfly valve is also called butterfly valve, as the name suggests, its essential components like a butterfly against the wind, and free turning. The butterfly valve disc is the disc, around the seat of a shaft rotation, the dimension of the angle of turning is the valve open and also close.

Stainless steel butterfly valve

Butterfly valve introduction

Butterfly valves have been in use since the end of the 18th century. James Watt made use of a butterfly valve in his steam engine prototype. With advances in materials and modern technology, butterfly valves can be made smaller as well as can hold up against higher temperatures. After the Second World War, synthetic rubber was used for seals, enabling butterfly valves to be made use of in more sectors. In 1969, James E. Hemphill patented an improvement in the butterfly valve that lowered the hydrodynamic torque required to transform the valve's outcome.

The butterfly valve is a quarter-turn rotating movement valve used to quit, change as well as start the flow.

The butterfly valve can be opened up easily as well as promptly. The 90 ° rotation of the handle supplies complete the closing or opening of the valve. Large butterfly valves are usually equipped with a supposed transmission, where the handwheel is linked to the valve stem by equipment. This simplifies the operation of the valve but at the expense of speed.
As a result of their small dimension, easy framework, as well as light-weight, butterfly valves are increasingly used in piping systems such as cool and hot air, water as well as electrical power, environmental protection, structure supply of water as well as water drainage, as well as community engineering. Used as a tool for intercepting or intermediary flow. On several events, due to the benefits of the butterfly valve itself, it has been possible to change gate valves, globe valves, ball valves, and various other valves in industrial pipeline applications.
The structure of the butterfly valve is very straightforward, with just a few basic parts such as the valve body, valve stem, valve disc, valve seat, and transmission. Although the framework is basic, the feature of the butterfly valve can not be ignored. The little framework has terrific practical value.
The butterfly valve can be used to readjust the flow. When the flow adjustment butterfly valve requires to be under special working conditions, or in a closed environment, the performance needs are stringent, or the operating problems of the butterfly valve are seriously worn, low-temperature level, and other harsh work.

Butterfly valve parts

Below are the major butterfly valve components:

Valve Body

The valve body fits between the pipe flanges - the most common end connection types being flanged, double lug, and wafer types.

Disc

Attached to the valve body is the disc that functions as a gate that stops or throttles fluid flow; it can be considered equivalent to a gate in a gate valve, or a ball in a ball valve. The disc is typically bored to receive the stem, or shaft. There are many variations in disc design, orientation, and material in order to improve flow, sealing, and/or operating torque. For example, Hawle’s 9881k double eccentric disc is designed to reduce seal wear and “scuffing” as well as operating torque requirements.

Cast iron rubber lined butterfly valve

Seat

Lining the internal valve body is a strong elastomer or metal anti-leak seal that secures the disc in place in the closed position in order to achieve complete shutoff. The 9881k series’ stainless steel weld filled and microfinished integral body seat ensures a corrosion and erosion resistant seat face. With this special type of seat design, it is possible to manufacture the valve drop tight according to EN12266 –A requirements.

Stem

The valve shaft, often also referred to as the stem, is the component that connects the disc to the actuation mechanism and transmits the torque through itself.

Seals

Seals are present at multiple interfaces within the valve to either ensure a tight seal during operation or to isolate the process media from the valve’s internal components for a more flexible and cost-efficient design.

Sealing on seat face is ensured by a continuous T-profile resilient sealing ring which is held on the periphery of the disc by a retaining ring, preventing the sealing ring from rolling out. In the closed position, the sealing ring is pressed against the seat face, providing a tight seal on both the upstream and downstream ends. In the open position, the sealing ring is completely unstressed due to the double eccentric disc design.

By eliminating interaction between the process media and the stem/shaft, the multiple O-ring shaft sealing system ensures a maintenance-free sealing for the entire life span of the valve. Besides, there are smaller more common components such as the bushings, bearings, and fasteners that are part of most other valve constructions as well. Details on some of the components on the actuation end, such as the handle, lever, gearbox, and handwheel will be covered in the actuation section.

Butterfly valve: working principle

The construction of a butterfly valve is relatively simple, with the rotation of the valve disc controlling the fluid flow. In the closed position, the disc blocks the valve bore while in the open position, the disc is oriented perpendicular to the flow direction to allow flow. Butterfly valves generally provide bi-directional flow and shutoff capability. However, they are not full-bore, which renders them unsuitable for pigging or swabbing. The body material is ductile iron with an epoxy powder coat on both internal and external surfaces. The valves are typically operated by handwheels, gears, or actuators, or a combination thereof, according to the specific application requirement and technical specifications. We will be discussing the actuation methods later in the article.

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