Valves are devices used to control the pressure and flow of any particular substance such as gases, liquids, fluidised solids, and slurries within a system. The valves are also known as ‘Regulators’ for the same reason. There are different types of valves used in a wide variety of applications in various industries. You will find air valves, backflow preventers, ball valves, butterfly valves, compressor valves, control valves, gate valves, diaphragm valves, globe valves, and many more. All these valves vary significantly in design, size, and function. However, this article will discuss one specific category of valves, namely, the Butterfly Valve. Here, you will learn about its uses, types, and functioning. So continue reading!
What are Butterfly valves?
Butterfly valves belong to the quarter-turn rotational motion valves family and are widely used in various pipelines to control, stop or start the flow. It is called so because it has a metal disc that moves like a butterfly wing. Its motion is similar to a butterfly landing with wings moved up and down with a 90-degree motion. This metal disc is attached to a rod, and when this rod rotates the disk perpendicularly, the valve opens or closes.
It has four main components:
- Valve body: The valve’s body fits between the two pipe flanges. It is available in two primary styles- wafer and lug.
- Valve stem: Stem plays the most critical role in the functioning of valves. It connects the disc to the handle placed outside, with which the valve opens and closes.
- Disk: It controls the flow of the substance through the valve.
- Valve seat: It is made up of different polymers or elastomers and runs along the inner diameter of the valve.
Valves can be categorised depending on their closure design, actuation method, and connection design. Read on!
- Based on disc closure design
- Based on the operation method
- Automatic Actuation
- Manual Actuation
- Based on the piping connection
- Lug type
- Wafer type
Butterfly valves are used across diverse and demanding applications, particularly in large volume water applications and slurry applications. These valves are designed to offer functionality and reliability in various industries, including agrochemical, base chemical, specialty chemical, and fluorochemical. Some typical applications include:
- Gases, air, cooling water
- Domestic piping, ships, firefighting apparatus.
- Slurry and similar applications
- Vacuum service
- High-pressure and high-temperature water and steam services
- Compressed air or gas applications.
How does it work?
The construction of these valves is relatively simple and can be operated electronically, manually, or pneumatically. When operated electronically, a signal from a remote source nifty the gearbox, positioned on the top of the valve body to turn the system and allow the disc to move. If pneumatically operated, there will be a piston attached to the side of the body to allow the inflow of air pressure required to open the valve.
A handle is turned a quarter-turn to open the valve. Inside the valve body, the disc changes position from perpendicular to parallel so that the media can flow across it. Further, the disc moves away from the valve seat towards the centreline to allow the passage of the medium in full force. Another quarter turn is made in the opposite direction to close the Butterfly Valve, and the position of the disc again changes to perpendicular. It positions itself to the valve seats, and this is a fully closed position. Depending on the applications, they offer significant advantages as they are lightweight and compact, require low maintenance, provide fast operation, and are a cost-effective solution.