| 摘要 |
A magnetic sensing device for sensing the proximity of a gas lift plunger up from the bottom of an oil or gas producing well is used to initiate the off cycle of the well and which comprises only one moving component, a magnet which is attracted to the plunger, completing an electrical circuit to a unit for controlling the operation of the well. The magnet is returned to its resting position by a ferrous set screw adjacent the magnet which attracts the magnet once the gas lift plunger has passed the field of the magnet sensor. The magnet and electrical contacts for the sensing device are enclosed in a molded plastic housing which can be easily opened to repair or replace any worn components.
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