Butterfly Valves

What is a Butterfly Valve?

A butterfly valve is a type of flow control device used to regulate the flow of liquids, gases or other substances through a pipe or duct. It consists of a circular disk mounted on a shaft and inserted into a pipe or channel. The disc is attached to a lever or lever used to open and close the valve by turning the disc. When the valve is opened, the disc is rotated parallel to the flow of the material, allowing the material to pass through the pipe or channel. When the valve is closed, the disc is rotated perpendicular to the flow, blocking the passage of the substance. Butterfly valves are often used in piping systems to control the flow of liquids, gases and other substances and are known for their simplicity, low cost and ease of maintenance.

How Does the Butterfly Valve Work?

A butterfly valve is a type of quarter-turn valve that uses a flat disc-shaped shut-off element to control the flow of fluids through a pipe. The closure or disc is mounted on a shaft that runs through the center of the pipe and is sealed with a gasket or O-ring to prevent leakage.

To open the valve, the disc is rotated a quarter turn parallel to the flow of fluid. This allows the liquid to pass freely through the valve. To close the valve, the disc is rotated a quarter turn in the opposite direction perpendicular to the flow of fluid. This blocks the flow of fluid and stops flow through the valve.

Butterfly valves are commonly used in piping systems to control the flow of liquids and gases and are particularly useful in applications where high flow rates are required, such as water treatment plants or oil and gas pipelines. They are relatively easy to install and maintain, making them a popular choice for many industrial and commercial applications.

What is the Flow Characteristic of Butterfly Valves?

There is a proportionality between the amount of flow passing through the opening of the valve disc, which can be considered as a direct ratio. It is theoretically accepted that when the flap opening is X%, the flow amount will be as much as X% of the total flow that the valve can pass.

In butterfly valves, there is a logarithmic (parabolic) relationship between the equal percentage flow characteristic, the valve opening and the amount of flow passing through. The application of equal percentage flow characteristic in butterfly valves is very limited and globe control valve comes to mind when equal percentage characteristic is mentioned.

The equal percentage flow characteristic provides a precise control in temperature and pressure control, and the advantages of butterfly valves compared to globe valves in terms of size and weight make them an important reason for preference, especially in large diameters.

Where Are Butterfly Valves Used?

Butterfly valves are used in a variety of industries and applications, including:

• Water and sewage treatment plants: Butterfly valves are often used to control the flow of water into and out of treatment tanks and ponds.
• Chemical handling: Butterfly valves are used in chemical plants to control the flow of chemicals in pipelines and tanks.
• Oil and gas: Butterfly valves are used in the oil and gas industry to control the flow of oil and gas in pipelines.
• Power generation: Butterfly valves are used in power plants to control the flow of steam and other fluids in the production process.
• Food and beverage processing: Butterfly valves are used in the food and beverage industry to control the flow of liquids such as milk and beer through pipelines and tanks.
• Pharmaceutical: Butterfly valves are used in the pharmaceutical industry to control the flow of liquid and gas in the manufacturing process.

What are the Butterfly Valve Types?

There are several types of butterfly valves, including:

• Wafer Type Butterfly Valve: This type of valve has a wafer-like body designed to fit between two pipe flanges. It is a lightweight and cost-effective option that is ideal for use in low-pressure systems.
• Lug Type Butterfly Valve: This type of valve has ears attached to the valve body. These shoes are used to bolt the valve to the pipe flanges, making it a good choice for high pressure systems.
• Flanged Butterfly Valve: This type of valve has a flange attached to the valve body. The flange is used to bolt the valve to the pipe flanges, making it a good choice for high pressure systems.
• Double Flanged Butterfly Valve: In this valve type, there is a flange at each end of the valve body. It is designed for use in high pressure systems and is often used in the petrochemical industry.
• Triple Offset Butterfly Valve: This type of valve has an offset body that provides a tight seal against the seat. It is a high performance valve used in high pressure and high temperature systems.
• Rubber Seated Butterfly Valve: This type of valve has a rubber seat used to form a seal against the valve body. It is a good choice for use in corrosive or corrosive environments.
• Metal Seated Butterfly Valve: This type of valve has a metal seat used to form a seal against the valve body. It is a good choice for use in high temperature environments.

What are the Points to Be Considered in Butterfly Valve Installation?

Before the installation of butterfly valves, the surfaces of the flanges of the valve and the pipeline must be clean, and the pipelines must be cleaned of all kinds of dirt and welding slag.

All values on the valve label must be checked and checked for compliance with the process.

In order to prevent any deformation of the disc contact ends during assembly, the disc should be partially open, but the disc should not exceed the thickness of the valve body.