Retrofit device for alfalfa valves

摘要

A device is described to retrofit an alfalfa valve, without modification of the valve, to convert it from manual to pneumatic control and provide means for closure of the valve if operating pressure to the system is interrupted. The device comprises a first vertical shaft with a short upper threaded portion to secure the shaft to the cover of the alfalfa valve and a lower unthreaded portion; a second vertical shaft above the first shaft and coupled thereto; a chamber including pneumatic means for raising and lowering the shafts, wherein the shafts are in the raised position when the chamber is under pneumatic pressure; a horizontal plate connected to the bottom of the chamber and having a central hole to permit the second shaft to pass therethrough; leg means to stand the plate on top of a flange upon which the cover of the alfalfa valve sits, and means to clamp the plate to the flange.