Technical Articles

Difference Between Offset/Eccentric and Concentric Butterfly Valve

Choosing the wrong type of valve can be detrimental to your operation. There are a few different types of butterfly valves on the market, including the offest/eccentric and concentric butterfly valve.

Center line butterfly valve is widely used in water treatment and other industries, because of it’s advantages: light weight, small size and easy for installation, low cost. But thanks to it’s design, it’s limited in many cases, and offset/eccentric butterfly valve could help. Below are some basic difference between center line butterfly valve and offset butterfly valve.

Appearance:

You could easily distinguish them from the appearance, because all the total different design structure.

Internal Difference:

1. Center line butterfly valve disc is simple, just a disc, but eccentric butterfly valve disc also combined with disc seal, seal retaining ring, and retaining bolt.

2. The sealing of center line is also simple, the disc touch the rubber seat directly, while eccentric butterfly valve with a additional laminated disc seal touched with a meat body seat.

3. Eccentric butterfly valve seat is meat while center line butterfly is only soft seat, could be integral body seat or replaceable welded seat.

Application：

1. Center line butterfly valve can only reach a pressure of 150LB/PN25, while offset butterfly could up to 600LB/PN100.

2. Temperature. Because of the different design of the seal structure, the center line rubber seat can’t bear a high temp, but offset butterfly valve could work with hard seal design.

The advantages and disadvantages are apparently, and very easy to choose which one to use for a real condition. When the pressure is high, or requires a high temperature, must used a eccentric butterfly.

Our Variety triple eccentrice butterfly valves: