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Method and apparatus for controlling a progressing cavity well pump
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Method of calibrating a well pumpoff controller
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Determination of well pumping system downtime
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Gas lift optimization
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Gas gun for determining the liquid level of a well
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Method of and apparatus for recording, storing and replaying dynamometer data from a liquid well pump
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Control circuit for shutting off the electrical power to a liquid well pump
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Polished rod load transducer
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Malfunction detector circuit for the use with a pump-off control circuit
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Control circuit for shutting off the electrical power to a liquid well pump
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Method and means for selectively positioning a light source for illuminating film transparencies
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Apparatus for measuring the change in the thermal energy of a flowing fluid
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