How Do Butterfly Valves Work?

Butterfly valve is one of the best selling fluid equipment pipeline in Pindee valve.In their company one type of the high-performance butterfly valve made in China is a quarter turn valve that is most suitable for handling large amounts of liquids or gases. Butterfly valves are easy to operate and can be used for many flow control and throttling applications. In this article, we will show you the general working principle of butterfly valves.

How Do Butterfly Valves Operate?

The disc component can be operated through multiple ways. It can be through a packing from a pneumatic actuator, an electric motor, a solenoid or a hydraulic piston and cylinder.

How to Make Butterfly Valves Work with a Handwheel

To make it work, simply turn the handwheel to its open or close position. This is the simplest (and oldest) way to operate a butterfly valve. Hence, they are not automatic. Manually-operated valves can be equipped with a lever, wheel or a gear connected to the stem. These valves are typically used in systems that do not require automatic operation.

These are power-operated valve actuators which initiates automatic opening and closing of the valve. Some of these valves have switches so you can remotely monitor the position of the disc. Thus, the purpose of the handwheel in this type of system is for emergency reasons when power is not available.

How Pneumatic Actuators Make Butterfly Valves Work

Pneumatic actuators are driven by air or gas. It can operate automatically or semi automatically. The design is quite simple and easy to operate.

1. A certain pressure range has been set in the system.

When the system detects that the air pressure is about to exceed, the diaphragm will adjust the opening and closing amount of the butterfly valve.

3. Pneumatic valves can be used for throttling or as throttling butterfly valves.

This type of operation does not use limit switches like electric butterfly valves, but instead uses the following operations:

Spring Return - Air pressure causes the spring to move, thereby moving the valve stem.

Double acting - Air is applied at both inlets to initiate the movement of the valve from the closed position to the open position.

How do hydraulic actuators make butterfly valves work?

Basically, hydraulic actuators activate valve movement by sensing fluid pressure. These types of valves are used for applications that can withstand tremendous forces.

1. Fluid pressure acts on the piston cylinder, converting it into linear motion.

2. The piston is connected to an actuator that converts linear motion into rotational motion.

3. Its torque starts the movement of the butterfly valve stem, which opens when the pressure is higher than the set value and closes when the downstream pipeline needs to release air.

How Electric-Operated Butterfly Valves Work

These types of valves use electric actuators to operate the valve in the open and closed positions.

Electric butterfly valves require electricity to operate. It is one of the most reliable solutions in large factories and applications.

Consider body materials

It should also be noted that butterfly valves come in many body, disc, and seat materials, suitable for different applications. Aluminum valves are used for lightweight applications; Stainless steel butterfly valves are used for conveying corrosive media; Carbon steel (WCB high-performance butterfly valve) is used for high-strength and high-temperature applications; Austenitic steel valves are used for low-temperature applications.

Consider seat materials

The valve seat material can be a metal valve seat or an elastic valve seat. The difference between them can be easily seen from their structure. Metal seat valves have metal to metal contact points and, unlike elastic seat valves, do not have elastomeric or PTFE seats.

The temperature resistance, pressure resistance, and sealing performance of each valve are also different. Although metal seat valves are very hard and can withstand high temperatures without wear, they are not as good as elastic seat valves in terms of sealing. On the other hand, elastic seat valves may not be able to withstand high temperatures.

Consider offset design

The offset design of butterfly valves also varies. There are three types of offset designs: zero offset, double offset, and triple offset. Usually, soft seat valves are concentric/lined/zero offset types, while metal seat valves are eccentric designs (double offset or triple offset).

How does the zero offset butterfly valve work?

The stem line of the concentric or zero offset butterfly valve is located at the center of the valve body, and the valve disc is located at that center.

As this is the simplest design for butterfly valves, it is clearly suitable for general service types. This can be used for applications that do not require high pressure and high temperature. In fact, zero offset butterfly valves can only be used in systems with a maximum pressure of 250 psi and a temperature of 400 degrees Fahrenheit. Therefore, they are used for the lowest level standard, which is a 150 level rating.

The valve stem is connected to the center of the valve disc and to the actuator. The actuator can be powered by a power source, pneumatic diaphragm, hydraulic piston, or manually turned handwheel.

When the system reaches the set pressure, the actuator forces the valve disc to move parallel or perpendicular to the flow of the medium. Parallel allows fluid to pass through; Vertical to prevent fluid flow.

For throttling services, the valve can be slowly opened to allow a small amount of medium to pass through.

How does a double offset butterfly valve work?

For high-temperature and high-pressure applications, we cannot use zero offset butterfly valves. Metal seat valves are suitable for this type of application because they have higher mechanical performance than soft seat valves.

Double eccentric butterfly valves are suitable for heavy-duty applications such as high temperature and high pressure, as their double offset design is designed to prevent metal to metal valve seat wear. The dual bias design can also prevent friction between metal surfaces when closing the valve.

How does the triple offset butterfly valve work?

Compared with double offset concentric butterfly valves, the manufacturing and assembly of triple offset butterfly valves are very difficult. Therefore, it is the most expensive. But its expensive price brings greater benefits, especially for systems that require high-performance valves.

Triple offset valves are commonly used for tight closure in pipeline systems for oil and gas applications.

The three offset butterfly valve has three offsets, all of which are installed eccentrically. This helps to provide a tighter seal. In this type of valve, a dual offset design and additional offset of the valve seat axis are combined.

Adopting a triple offset design can eliminate sliding between the valve seat and the valve disc. Recommended for high pressure and high temperature applications, such as ratings ranging from 150 to 600.

Pindee Valve is a high-performance butterfly valve manufacturer in China. We have a variety of butterfly valve product combinations, including different seat designs, valve bodies, disc and stem materials, and end connections. We also provide OEM/ODM services. If you need more information and quotation requests, please feel free to contact us at any time.Our email address: sales@pindee.com