Butterfly valve

Butterfly valve is one of the most widely used types of valves in the piping industry. This type of industrial valve is one of the most widely used types because it is light in weight and its movement is fast and at the same time it has a lower price and is more suitable than other industrial valves, so to choose and check the price and buy a butterfly valve, you must first understand their differences and parameters.

Types of butterfly valves

Based on the type of operator

Lighter valves usually have a manual operator, while heavy valves are opened and closed with the help of actuators.

  • Lever Handle

Lever Handle Butterfly valves are used in cases where the valves have small size and there is not much pressure behind the valve. The amount of fluid is not particularly important.

  • Gearbox Operated

When there is so much pressure behind the butterfly valve, or the output flow rate is important, or when the butterfly valve is so large that it is practically impossible to use the lever, the Gearbox Operated butterfly valve  is used.

  • Butterfly valve with actuator

If the opening and closing speed of the valve is important, or there is a lot of pressure behind the valve, and where the flow rate of the valve is important, and also for control of the valves from the control room, a butterfly valve with an actuator is used.

1- with electric actuator
2- with pneumatic actuator

How does a butterfly valve work?

Butterfly valve function

In response to the question of how a butterfly valve works, we must say that a butterfly valve refers to the closing part (disc or butterfly plate) of a disk that rotates around the valve shaft to open and close. It mainly plays the role of cut-off and gas valve in the pipeline.

The opening and closing part of the valve is a disk-shaped impeller plate that rotates around its axis in the valve body to achieve the purpose of opening and closing or regulating the fluid in the pipeline.

Butterfly valves are usually less than 90 degrees from fully open to fully closed. Butterfly valve and butterfly stem are not self-locking. A worm gear reducer must be installed on the valve stem to determine the position of the impeller plate. The use of worm gear reducer can not only make the impeller disc self-locking, stop the impeller disc at any position, but also improve the operation performance of the valve.

Butterfly classes

  • Class 150
  • Class 300
  • Class 600
  • Class 900
  • Class 1500
  •  2500
  • Class PN10
  • PN16
  • PN25

Butterfly valve components

  • body
  • Disc
  • operator
  • Seat

The butterfly valve disk is a part that has a direct connection with the fluid and must be made of material with appropriate resistance, so alloy steel, all steel with different grades, nickel and bronze alloys, etc. are usually produced and used.

Body: The body of the valves corresponds to two pipe flanges, which is the most common body design of log and wafer type.

Disk: A disk is an element that stops the flow. There are changes in disc design and orientation to improve flow, sealing and operating torque.

Stem: The stem consists of a one-piece or two-piece shaft design. Stem design should avoid the potential for knocking between similar corrosion-resistant materials.

Seat: To create a butterfly valve seat, it uses the interference between the edge of the disc and the seat. The valve seat may be stuck to the body, compressed or locked.

When not to use a butterfly valve?

– If the movement of the disc is affected by the flow turbulence.

– Poor sealing is not suitable for high differential pressure conditions.

In the following, you will learn about the types and structure of butterfly valves. You will be able to have a successful purchase based on the features you need.