Abstract: A fluid detection system by which the presence or absence and identity of fluids may be detected within confined areas, such as those existing within underground storage tank systems and in which fluids may accumulate. The fluid detection system includes a probe assembly having circuitry which determines the presence of fluids by the capacitance developed across a variable capacitor. The output signal provided by the capacitor is converted to frequency values, is filtered by a receiver included with the system, and transmitted to a remote location for display. The system is suitable for deployment within and monitoring of one or a multiple of tank systems.

Abstract: The invention is a novel method and apparatus for counting pipe joints, passing through a bell nipple, going downhole and uphole by sensing, at spaced apart positions along the nipple utilizing magnetic fields, for the presence of a joint. Each sensor develops signals as the joint passes it and a logical network determines which direction the pipe joint is traveling, adds a plus count to the joint counter for joints going downhole and subtracts a minus count from the joint counter when a joint is sensed coming uphole. Another logical circuit converts the joint count to a stand count, and the negative signals from the stand count trigger an adder network to introduce a binary number to a numeric read-out display, which number is indicative of pipe displacement per stand, withdrawn from hole.