Xul . 17, 2024 15:53 Back to list

The Internal Components of a Butterfly Valve

Gate, Ball, Butterfly Oh My! In today’s world there are so many valve options that it can be hard to know what they all do.

Butterfly valves are a quarter turn valve that is simple in design and easy to use. The components of butterfly valves are made up of four main parts: the body, disk, stem, and the seat. In today’s post, we’ll take a closer look at how each of these parts allows the butterfly valve to perform in industrial applications.

Four Main Parts of the Butterfly Valve

Butterfly valves are a quarter-turn rotational motion valve that can start, stop, and regulate flow. They are simple to use, which makes them a popular choice. Below are the parts of a butterfly valve and how they contribute to the function of the valve.

Body

The body of the butterfly valve is the part that fits between the two pipes. This slim valve comes in two major body styles: wafer and lug. The wafer style body is the most economical of the two. It is connected to the pipes with bolt holes that run through the body of the valve. This design is easy to install and primarily used to prevent backflow in universal flow systems. However, it should be noted that they are not recommended for use in systems that require regulation.

Lug style butterfly valves are slightly more expensive than their counterpart but offer a few distinct advantages. Lug butterfly valves are connected to the pipe through protruding lug holes on the outside of the body of the valve. With this design, the valve actually helps carry the weight of the piping throughout its body, unlike the wafer valve. This allows for removing piping from one side of the valve for dead-end servicing.

Disk

Both wafer and lug style butterfly valves have a disk inside, and this disk is what controls the flow of media through the valve, much like a gate in a gate valve or the ball in a ball valve.

The disc of the valve can be either concentric or eccentric. The simplest of these two is the concentric disk. In the concentric design the stem passes through the centerline of the disk. Concentric valves are commonly used in low pressure applications.

The eccentric disk design, however, has a stem that doesn’t pass through the center line, but rather behind it, in the opposite direction of the flow. The eccentric disk was first designed to help prevent contact of the disk and seal before it was fully closed to help prolong and improve life of the valve.

Groove Butterfly Valve

Stem

The stem of the butterfly valve may seem like a small part, but it plays an important role. The stem is what connects the disk inside to the handle outside. Without it, the valve would not be able to open or close, and what’s a valve if it can’t open or close?

The stem has two different designs—wetted or non-wetted—which refers to the protection on the stem. Non-wetted stems are protected against any potential corrosive or erosive media in the line. Wetted stems are not protected against these and, thus, must be made of material that is compatible to the media flowing through the line.

Seat

The seat of a butterfly valve is made of different elastomers or polymers and is either bonded to the body or pressed or locked down. The seat runs along the inner diameter of the valve. When the disk presses along the seat, they seal together to stop the flow. When butterfly valves were first designed the metal of the disk sat against the metal body, which did not provide a tight, leak-free seal. The addition of elastomers or polymers to the design of the valve is what helps provide the leak-proof seal.

Manual Actuation vs. Automatic Actuation

One major advantage of butterfly valves is that they can be operated either manually or automatically to fully rotate the disc inside the valve.

Manual actuation for butterfly valves involves either a hand lever or gears. Hand levers are used primarily on smaller valves, and much like their name implies, are a lever on top that is rotated up to 90 degrees to open, close, or regulate flow.

Gear operated valves are used on bigger valves and utilize a gearbox to help open and close the valve. While the gearbox does make it easier on the operator to open the valve, it does come at the price of a decreased speed.

The ability of butterfly valves to be operated automatically allows them to be controlled remotely. Automatic actuation occurs by use of either an electric motor, hydraulic pressure, or by pneumatic pressure.

Automatic butterfly valves are extremely helpful with larger valves (butterfly valves have been produced as large as 200inches!), and come with fail safe options like fail-open (open in case of failure) or fail-close (close in case of failure).

Industrial Applications for Butterfly Valves

With a slim design and inexpensive nature, butterfly valves are common in many industries. Combine that with their ability to stop, start, and regulate flow and they become the top choice for industries such as vacuum services and fire protection.

They are also able to withstand pressures between 150psi to 740psi cold working pressure, and temperatures up to 300°F, making them a top choice for high-pressure and high temperature water and steam applications.

Benefits of Butterfly Valves

With its four main components allowing for easy operation, it’s clear why butterfly valves are a popular choice in so many different industries. Their slim design can make them seem simple, but the components of the butterfly valve are all vitally important and work together to ensure a valve that can do a lot.

When searching for a valve to open, close, or regulate flow be sure to consider the butterfly valve and its many options to find one that best suits your needs.

Xul . 17, 2024 15:53 Back to list

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