Pneumatic valve interlock system

Claim 1

In combination with a plurality of valve assemblies each having an external valve operator movable between first and second positions for controlling the opening and closing of the valve assembly, the valve operator of each valve assembly being normally maintained in said first position, and a fluid-actuated interlock system cooperating with the operators of said plurality of valve assemblies for permitting only one of said operators to be moved away from said first position at any one time, said interlock system comprising: a pressure fluid supply line, and means connected to said supply line for supplying pressure fluid thereto; a control manifold adapted to have pressure fluid supplied thereto; a plurality of conduit means disposed substantially in parallel and connected between said supply line and said control manifold, one of said conduit means being associated with each of said valve assemblies; fluid switching means associated with each of said conduit means for normally preventing the flow of pressure fluid from said supply line to said control manifold, said fluid switching means being mounted adjacent the respective valve assembly and having a switching member movable between first and second positions, said fluid switching means having means associated therewith for normally maintaining said switching member in said first position wherein said conduit means is open and permits the flow of pressure fluid from said supply line to said control manifold, said switching member being engaged with the valve operator of the respective valve assembly when said valve operator is in said first position so that said switching member is maintained in said second position wherein said conduit means is closed to thereby prevent the flow of pressure fluid from said supply line to said control manifold; a fluid-actuated locking device disposed adjacent each said valve assembly for preventing movement of the respective valve operator away from said first position when the respective locking device is energized, said locking device including a locking member movable between a deenergized position wherein said locking member is disengaged from the respective valve operator and is spaced from the path of movement thereof, and an energized position wherein the locking member is positioned in the path of movement of said valve operator to prevent any significant movement of said valve operator away from said first position; and passage means associated with each said locking device for interconnecting said locking device to said control manifold to permit energization of said locking device when pressure fluid is supplied to said control manifold; whereby movement of one valve operator away from said first position causes the associated switching means to be opened to thereby supply pressure fluid to the control manifold, which in turn supplies pressure fluid to the locking devices associated with the remaining valve assemblies to thereby energize said locking devices and hold the valve operators associated with the remaining valve assemblies in said first position.