Butterfly Valve – double offset (soft seat)
Butterfly Valve – KKD-81W
In a center lined butterfly valve, the stem is centered in the middle of the disc and the disc is centered in the bore.
In this type of valve, the disk first interacts with the seat at about 85° for a 90° rotation.
Center lined butterfly valves are widely used in low-pressure applications.
The wafer body type of the butterfly valves has been designed to keep a tight sealing, to protect against bi-directional pressure differentials, and to prevent backflow in devices built for uni-directional flow.
This is accomplished by using a tight-fitting cap, such as an O-ring, as well as a smooth valve face on both the downstream and upstream parts of the valve.