Product description:
API 609 design standard

Principle of operation:
The Cowinns triple off set butterfly valve provides a bi-directional bubble tight shut-off. This geometry ensures that the disc seal contacts the body seat only at the final shut-off position without rubbing or galling, providing a torque generated resilient seal with sufficient "wedging" to ensure a uniform seal contact.

The triple off set geometry
Offset 1:The shaft is offset behind the seat axis to allow complete sealing contact around the entire seat.
Offset 2:The shaft centerline is offset from the pipe and valve which provides interference free opening and closing of the valve.
Offset 3:The seat cone axis is offset from the shaft centerline to eliminate friction during closing and opening and to achieve uniform compressive sealing around the entire seat.