Emergency shut down device

Claim 1

An emergency shut down device for a reciprocable valve comprising: (a) a base member for connecting said device to a valve housing, said member having a central bore therethrough; (b) a spring cartridge assembly including a generally cylindrical container having first plate means at one end, second plate means at the other end, an opening in said first plate means to receive said base member, an opening in said second plate means of a diameter greater than that of the first-mentioned opening, annular ring means in said container, and compression spring means between said first plate means and said ring means; (c) an annular ram cup connected to and extending from said ring means toward said first plate means, said ram cup having a closure plate provided with a central opening, at the end distant from said ring means; (d) a cap member connected to the exterior of said second plate means to cover the second-mentioned opening; (e) a cylinder connected to and extending from said cap member into the interior of said ram cup; (f) piston means sealingly slidable within said cylinder; (g) stem means connected at one end to said ram cup and extending through the central opening in said ram cup, the interior of said assembly and said bore in said base member for connection to said reciprocable valve; and (h) inlet means in said cap member for admitting fluid under pressure to a chamber formed in said cylinder between said cap member and said piston, whereby fluid under pressure in said chamber will move said piston to abut said ram cup and then move said ram cup to extend the stem means from the base member and to simultaneously compress the spring, a loss of pressure permitting the spring to rapidly return the ram cup, piston and stem to an unextended condition.