Patent ID: 6152167
Filing Date: 2000-11-28
Classification: F16K,Y10T

Abstract:
A valve actuator for a valve in a line, comprising:a housing;a shaft mounted to said housing for movement between an open and closed position corresponding to the open and closed position of a valve to which the actuator can be mounted;a drive assembly to move said shaft between said open and closed positions;a biasing member acting on said shaft to urge it toward one of said open or closed positions known as the failsafe position;a shutdown system to selectively release said shaft from the position in which it was placed by said drive assembly to allow said biasing member to urge said shaft toward said failsafe position, said shutdown system comprising:a shutdown housing;a tripping member movably mounted in said shutdown housing and operably connected to said drive assembly;independently operating high- and low-pressure trip assemblies, each operably connected to said tripping member for actuation of said tripping member when pressure in the line is outside a predetermined pressure range.