The butterfly valve is part of the quarter-turn valve family. Upon rotating a quarter turn, the disc opens or shuts down completely. In essence, it is used to control fluid flow through a pipe section.
The butterfly valve is designed to provide total flow with a high level of control efficiency. The positive shut-off is not possible with butterfly valves. Due to recent developments in polymers and increased temperature ratings, butterfly valves with bubble-tight closure have been developed.
Working Principle of Butterfly Valve
A butterfly valve works by placing a flat, round plate in the center of the pipe. The plate is connected to an actuator on the exterior of the valve by a rod. When the butterfly valve actuator is rotated, the plate is either parallel to the flow or at an angle to the flow. When compared to a ball valve, the plate is always present inside the flow, causing a pressure drop regardless of where the valve is positioned.
Butterfly valves are formed from a metal disc clasped on a rod. When the valve is shut, the disc is rotated so as to completely block the passageway. If the valve is fully open, the disc is quarter-turned to allow the fluid to flow unrestricted. The actuator is rotated by one-quarter turn from 0A degree to 90A degree to shut down or start a butterfly valve. A butterfly valve is operated by a variety of actuators based on its size and purpose. There are different types of butterfly valves, and each one can handle a variety of pressures and applications. The resilient butterfly valve based on rubber’s elasticity has the lowest pressure rating. High-performance ones are also used in high-pressure systems.
Components of a Butterfly Valve
In addition to the outer case, butterfly disks, stems, rugged positioning plates, packing, and actuators are all part of the butterfly valve. It provides extra protection in the event that the seal created by the seat becomes damaged since the packing creates a strong seal that surrounds the stem. There are butterfly valve manufacturers in India, who use only high-quality graded raw materials to adhere to the valve performance.
When the valve is closed, metal discs, also known as butterfly valves, sit atop rods that prevent liquid from passing. Essentially, the disc movement depends on whether the valve is opened or closed. Furthermore, if the valve is completely open and the disc is rotated 90 degrees, in that case, a greater amount of air or fluid will flow through.
To ensure a proper seal, the resilient seat is also attached to the body. The packing also provides an additional seal in case the resilient seat is damaged. A butterfly valve is composed of a circular body attached to a rotary movement disk closure member.
Types of Butterfly Valve
In large valve applications, butterfly valves offer advantages in terms of weight, space, and cost. Pneumatic, electric, and manual butterfly valves can all be classified.
Butterfly valve types available on the market include:
Thermoplastic butterfly valve
Different installation procedures are required for these valves, which are available in wafer or lug styles. However, wafer valves are more common. Most of the time, lug-style butterfly valves are used in applications with low-pressure ratings.
Triple offset butterfly valve
The valves are high-performance valves. For example, they are used in refineries and offshore systems that are subject to extreme conditions. In many triple offsets, the disc closure, as well as the metal on the metal seats, are used. It is fire-resistant and rated up to 600 pounds.
High-performance double offset butterfly valve
Butterfly valves are best suited for high-temperature and high-pressure applications. They can operate up to 1200 degrees F. Double offset discs and stems allow the disc to “cam” into position while closed. Cams are components of a mechanical linkage that convert rotary motion into linear motion or vice versa.
Inflatable seated butterfly valve
The butterfly valve uses an inflatable seat that surrounds the disk to form a seal. Pneumatically, the bladder is inflated after the disk has reached its closed position. Since the seal is formed after the disc has been closed, less torque is required to propel the disc to close in such valves.
Benefits and Drawbacks of Butterfly Valve
The Advantages of Butterfly Valves Include:
- A simple, affordable design with fewer parts that makes it easy to maintain and convenient to repair.
- Due to its wafer-form lightweight body, this valve is a budget-friendly option when considering both the initial price and installation costs related to in-person hours and piping requirements.
- Mud can be transferred with only a negligible fluid deposit at the pipeline outlet.
- At low pressure, they seal well and are easy to open and close.
- Compared to a ball, its disc is lightweight.
- Butterfly valves require significantly less structural support than ball valves of the same diameter.
The Disadvantages of Butterfly Valves Include:
- It is always the same part of the disc facing the flow, even when the disc is fully opened. Regardless of the setting, the operation of a valve results in a pressure switch.
- It has poor sealing capabilities.
- Butterfly valves are only suitable for applications with low-pressure drops.
- There is a possibility of cavitation and choked flow when butterfly valves are operating.
Applications of Butterfly Valves
The butterfly valve is widely used in automobile systems. In a car carburetor, for example, you can detect the butterfly valve. Therefore, the valve is used here to regulate airflow to the car’s engine. The valve can partially open and shut to control the flow of air.
Also Read: Top Reasons to Use Ball Valves for Flow and Pressure Control
As a result of their easy throttling capability and adequate pressure limits, butterfly valves are commonly used in firefighting pipes and tubes. Additionally, these valves are used in corrosive and abrasive environments. Also, they are used in high-pressure water and steam facilities that require high temperatures. A butterfly valve is also needed for vacuum service, cooling, and circulating water systems.
In addition, some of them, such as Triple Offset, are used in the oil, gas, petrochemical, power, chemical, and marine industries. Also, valves can be used for on-off systems or modulating services.
A large part of the popularity of butterfly valves in industrial applications can be attributed to their properties like quarter-turn functionality and tight shut-off. Furthermore, the latest designs and materials have enhanced its use in industrial fluid systems. The Aira Euro Automation is a well-known industrial valve manufacturing company in India.
Wrapping Up
Butterfly valves play a crucial role in pipelines by controlling the flow of water. Any flow of fluid or variable that is throttling the amount of flow can be stopped or started with these devices. Some valves function better in corrosive systems, while others are able to handle high-pressure fluids. What is your opinion? How do you ensure that your valves are performing properly?
