Patent ID: 6131594
Filing Date: 2000-10-17
Classification: F16K,Y10T

Abstract:
In an isolation gate valve assembly having a valve body presenting a passageway therethrough, a gate unit including a shiftable gate member proximal to said passageway and shiftable between a valve open position permitting flow through the passageway and a valve closed position wherein the gate member is located in flow-blocking orientation relative to said passageway, an improved actuator for shifting the gate member between said positions, said actuator comprising:an elongated tubular housing;a piston shiftable longitudinally of the housing;a piston rod connected to the piston and to the gate member for shifting the gate member between said valve open position and said valve closed position in response to movement of the piston,a gas generating cartridge unit having a gas discharge end,the cartridge being connected to the tubular housing in disposition defining an expandable pressurized gas-receiving chamber between the piston and the gas discharge end of the cartridge,said cartridge being provided with an ignitable gas generating charge which upon ignition burns at a controlled rate producing a flow of pressurized gaseous products of combustion which flow into the chamber at a rate that does not exceed a velocity of about mach 1,the piston being positioned for movement from an initial location adjacent to but spaced from the discharge end of the cartridge to an actuated location, by pressurized gas directed into said chamber from the gas cartridge to effect shifting of the gate member from one position thereof to the other position of the same,the piston in said initial position thereof being spaced from the discharge end of the cartridge a distance sufficient to prevent pressurized gas first entering the chamber upon ignition of the charge from imparting damaging shock forces to the piston, said rod connected thereto, or the gate valve,the gas generating charge being operable to move the piston and thereby the gate member from the initial location of the piston to said actuated location thereof at a velocity of from about 0.2 to about 0.33 in./msec.