Butterfly valves introduction

GOOLE Butterfly valves

There are many different designs of butterfly valve, but they all consist of a disc that rotates on a shaft at right angles to the fluid flow. When open, the disc is edge-on to the flow and the fluid passes around it, offering limited resistance. In the closed position, the disc is rotated against a seat in the body of the valve. 

Butterfly valves usually take up little more room than a pair of pipe flanges, and are therefore an attractive alternative to the ball valve where space is limited. In fact, some butterfly valves are designed specifically for insertion between pipe flanges, these are known as wafer butterfly valves.

The main disadvantage of butterfly valves is that the shut-off is not as tight as that achieved by other valve types. This can be alleviated to an extent by offsetting the axis of rotation of the disc and using pressure assisted seats. By using an offset axis of rotation, a 'camming' action is generated, which means that the disc creates a tight seal with the seat during the last few degrees of shut-off. These high performance or eccentric-type butterfly valves have improved shut-off capabilities and their design enables them to be used for throttling. 

For steam applications, butterfly valves have largely been superseded by ball valves. Butterfly valves are more commonly used in liquid systems or where space is limited. The compactness of butterfly valves means less material is required and they are therefore ideal where the application specifies the use of costly materials, for example, in seawater applications where nickel is specified.

GOOLE BUTTERFLY VALVES LINKS :

Wafer Lug FEP / PTFE/ PFA Lined Butterfly Valve

Wafer Type FEP / PTFE / PFA Lined Butterfly Valve

FEP / PTFE / PFA Lined Single Flange Butterfly Valve

FEP / PTFE / PFA Lined Flange Butterfly Valve