Sanitary Butterfly Valve are vital elements in many piping systems, playing a crucial role! Today, we'll explore their intricate structural principles and comprehensive componentry.

Butterfly Valve Structure
Basic Working Principle
A butterfly valve works like a rotating "door." It consists of a valve body, a valve disc, and a valve stem. In a piping system, the valve disc sits in the middle of the pipe, while the valve stem extends through the disc and connects to the actuator.

When fluid flows through the pipe, if the butterfly valve needs to be opened, the actuator receives the command and rotates the valve stem, which in turn rotates the valve disc. Generally, when the valve disc rotates parallel to the direction of fluid flow, the pipe passage is virtually unobstructed, allowing fluid to flow smoothly. This is like a fully open door, allowing people to enter and exit freely and allowing maximum fluid flow.

Conversely, to close the butterfly valve, the actuator rotates in the opposite direction, slowly rotating the valve disc to a position perpendicular to the direction of fluid flow. At this point, the valve disc acts like a closed door, tightly blocking the fluid path and preventing further flow. It's like tightly blocking an outlet with a plate.

This process is quite vivid, isn't it? By controlling the rotation angle of the valve disc, the flow rate can be precisely adjusted and cut off, easily meeting different operating requirements.

Sealing Principle
Sealing is a key performance characteristic of a butterfly valve. Its sealing relies primarily on the fit between the valve disc and the valve seat. The valve seat is typically made of elastic and wear-resistant materials, such as rubber and polytetrafluoroethylene.

When the butterfly valve is closed, the valve disc and valve seat fit tightly together. The elasticity of the valve seat material tightly wraps around the valve disc, sealing any gaps that could cause fluid leakage. It's like putting a tight lid on a cup, preventing the water from escaping. Furthermore, some butterfly valves incorporate special sealing structures between the valve seat and valve disc, such as lip seals or metal gaskets, to further enhance the sealing effect and eliminate the possibility of fluid leakage.

Butterfly Valve Components

Valve Body

The valve body is the "skeleton" of the butterfly valve, playing a crucial role. It not only determines the overall shape and size of the butterfly valve but also provides a foundation and support for the installation of other components. It is typically made of metal materials such as cast iron, cast steel, or stainless steel. These materials offer high strength and corrosion resistance, ensuring stable operation in harsh environments. For example, in the pipelines of chemical plants, where highly corrosive chemical fluids are present, a stainless steel valve body effectively resists corrosion, ensuring the proper functioning of the butterfly valve and, consequently, the safe and stable operation of the entire piping system.

Valve Plate

The valve plate is undoubtedly a core component of a butterfly valve. It is typically disc-shaped and located in the center of the valve body. The size and shape of the valve plate should be designed based on the valve body diameter and actual application requirements. The choice of material is also crucial and depends on the specific application scenario. In low-temperature environments or where high flow control precision is required, an aluminum alloy valve plate may be used because of its light weight and better adaptability to low-temperature environments, ensuring proper valve plate rotation and accurate flow control. In some high-temperature, high-pressure industrial pipelines, alloy steel valve discs are used. This material is strong and heat-resistant, capable of withstanding the immense pressures and temperatures.

Valve Stem
The valve stem acts like the "driver" of the butterfly valve, connecting the actuator and the valve disc, transmitting the actuator's power to the disc and driving its rotation. It must possess sufficient strength and rigidity; otherwise, deformation or damage during power transmission could occur, causing the butterfly valve to malfunction. The valve stem is typically made of high-quality carbon steel or stainless steel, and may receive special surface treatments such as chrome plating or zinc plating to enhance corrosion and wear resistance, extending its service life.

Actuator
The actuator can be considered the "power source" of the butterfly valve. It receives signals from the control system and then provides power to the butterfly valve through various means, such as electric, pneumatic, or hydraulic. Electric actuators are convenient to use and offer precise control, making them widely used in highly automated factories. Simply supplying the appropriate current drives the valve stem to open and close the butterfly valve. Pneumatic actuators offer the advantages of simple structure and fast operation. They are commonly used in applications requiring rapid response, such as in piping systems in the food processing industry, where rapid shutoff of fluids is crucial. Hydraulic actuators are suitable for applications requiring high output force, such as in large water conservancy pipelines. They can provide sufficient power to ensure stable butterfly valve operation.

Seals
We've just mentioned the importance of sealing, and seals are key components for achieving a good seal. In addition to the valve seat, seals also include auxiliary sealing structures such as sealing rings and gaskets. Sealing rings are typically installed between the valve disc and valve body, or where the valve stem extends from the valve body, to prevent fluid leakage. Gaskets are used at valve body joints, such as the connection between the valve body and the pipeline, to ensure leak-free operation. The material selection and design of these seals are highly critical, requiring them to meet sealing requirements while also adapting to diverse operating environments, such as pressure, temperature, and chemical resistance.

Other Components
In addition to the main components listed above, butterfly valves also have several other smaller parts, such as packing, glands, and lugs. The packing primarily fills the gap between the valve stem and body, preventing fluid leakage along the stem and providing lubrication and protection. The gland compresses the packing, ensuring a tight seal. The lugs, typically mounted on the valve body, facilitate installation and securement of the butterfly valve, ensuring it is securely connected to the piping system.

After understanding the structural principles and component parts of butterfly valves, you'll have a comprehensive understanding of them. Butterfly valves play an important role in various industrial piping systems and building water supply and drainage systems. Understanding this knowledge will be helpful for installing, maintaining, and using butterfly valves, ensuring they serve you better!