Abstract: A magnetically operated fail-safe cutoff valve of general application and particularly suitable for down hole fluid well applications is provided having a simple highly reliable valve for equalizing the pressure across the main cutoff valve while closed thereby permitting the same to be opened. All operating components can be either removably installed internally of a tubing string or as a portion of the string itself. In either case, typical wire line operations can be conducted through and past the lower end of the cutoff valve since the flow path of each of the illustrative embodiments provides an unobstructed linear flow path therethrough when the valve is open. The pressure equalizing valve includes multiple flow passages and is controlled by a shrouded annular armature operable independently of a tubular armature controlling the main cutoff valve. The two armatures may be located in either common or separate flux circuits.

Abstract: An armature position monitor for determining the position of an armature within a solenoid and any device controlled thereby. By way of example, the monitor is useful to indicate the position of a solenoid controlled valve such as a sub-surface safety cutoff valve by detecting and utilizing a signal generated in a solenoid actuator for the armature upon the movement thereof toward or away from its extended position to control the power supplied to the solenoid.

Abstract: A tandem solenoid fail-safe sub-surface safety cut-off valve for fluid wells controllable from the surface and suitable for installation at substantially greater depths than prior constructions. The valve assembly may be installable and retrievable either via wire line or tubing techniques and utilizes tandem electromagnetic means to operate either a flapper or a ball cut-off valve. The solenoid coils embrace a landing nipple portion of the tubing string or the tubing string itself and hold either type of cut-off valve open against spring pressure only so long as the coils are energized thereby providing surface control of the safety cut-off valve normally and assurance of closing of this valve by energy stored in spring means in the event of power failure through accident or some catastrophe as well as automatic closure if flow velocity increases beyond a predetermined safe value.

Abstract: A fail-safe sub-surface safety cut-off valve for fluid wells controllable from the surface and suitable for installation at substantially greater depths than prior constructions. The valve assembly is installable and retrievable via wire line technique and utilizes an electromagnetic means to operate either a flapper or a ball cut-off valve. The operating solenoid coil embraces a landing nipple portion of the tubing string and is outside the production flow. This solenoid supplies the power to open either type of cut-off valve and holds the latter open only so long as the solenoid is energized thereby providing surface control of the safety cut-off valve normally and assurance of closing of this valve in the event of power failure through accident or some catastrophe as well as automatic closure if flow velocity increases beyond a predetermined safe value.

Abstract: A fail-safe sub-surface safety cut-off valve for fluid wells controllable from the surface and suitable for installation at substantially greater depths than prior constructions. The valve assembly is installable and retrievable via wire line technique and utilizes an electromagnetic means to operate either a flapper or a ball cut-off valve. The operating solenoid coil embraces a landing nipple portion of the tubing string and is outside the production flow. This solenoid supplies the power to open either type of cut-off valve and holds the latter open only so long as the solenoid is energized thereby providing surface control of the safety cut-off valve normally and assurance of closing of this valve in the event of power failure through accident or some catastrophe as well as automatic closure if flow velocity increases beyond a predetermined safe value.