The butterfly valve is a flow-control valve that regulates the flow of the fluid with a quarter-turn rotation of the disc. A stem passes through the disc and is also connected to an actuator that controls the motion of the disc.
According to the position of this stem, a butterfly valve can be concentric o eccentric.
Concentric Butterfly Valve
The concentric butterfly valve refers to the butterfly valve whose stem isn’t only located in the center of the disc but also in the center of the pipeline. This kind of butterfly valve is common, simple, and of low cost. The concentric butterfly valve is also called zero offset butterfly valve.
However, the concentric butterfly valve has its own disadvantages: during the opening and closing of the valve, the disc may always contact some part of the valve body and cause friction. To avoid such friction, an eccentric butterfly valve is a good option.
Eccentric Butterfly Valve
More specifically, the eccentric butterfly valve could be single-offset, double offset, or triple offset.
The single-offset butterfly valve refers to the butterfly valve whose stem is still in the pipe’s centerline but located behind the disc. This design might reduce the friction between the disc and the top or the bottom of the valve. But generally, it’s similar to the concentric butterfly valve.
The double-offset butterfly valve refers to the butterfly valve whose shaft isn’t only located behind the disc but also not in the pipe’s centerline. In other words, there’re two offsets: the disc stem is offset from the disc body’s centerline and also offset from the pipe’s centerline.
This double-offset valve decreases significantly the wearing process and prolongs its operational life. For this reason, the double-offset butterfly valve expands its application to a wide range of industries that involves chemical material or requires high temperature, etc.
The triple-offset valve refers to the butterfly valve that has three offsets: two of them are located in identical positions as the double offset butterfly valve. The third offset refers is on the seating surface that is cone-shaped offering assuring a zero leakage under high temperature or high pressure.
Like the double-offset butterfly valve, the triple-offset butterfly valve can also be used in many industries. Moreover, the triple-offset butterfly valve can be used in many more
demanding and challenging applications.
As a professional valve manufacturer, Lituo Valve produces a great variety of butterfly valves. For more details, please check:
https://www.watersvalve.com/product-category/butterfly-valves/
