Scully Signal Company

Arthur W Shea

Francis V Stemporzewski, Jr

Gary R Cadman

Stephen F Tougas

Richard O Beaulieu

A fail-safe fluid transfer control apparatus has full redundancy in the response to various inputs such as overfill probe signals, ground detection signals, and the like. Independent microprocessor controllers independently evaluate the inputs and each output control signals to close a respective relay when the inputs indicate that fluid transfer may commence. The relays are arranged in series such that both must be closed for a fluid transfer to commence. The control signals from each controller include a static signal and an alternating signal, both of which must be properly output to close its respective relay. Each controller monitors the state of each relay, and discontinues its control signals if either relay appears to be malfunctioning. Each controller runs an different, independently written firmware program to process the detected inputs to prevent a common firmware error. An optical bypass key replaces conventional mechanical keys and transmits an optically encoded signal to the controller for establishing a bypass condition. A preheating circuit is also provided for providing a dynamic voltage supply to standard thermistor probes which may be encountered.

Fluid transfer controller with digital bitstream monitor

Method of overfill probe identification and control

Fail-safe fluid transfer controller

A remote level sensor for a residential fuel oil tank is adapted for a fuel oil gauge with a permanent magnet which changes position with changing fluid levels in the tank. The sensor has a housing with a connector which receives a top portion of the gauge such as to provide an alignment of the sensor with the gauge. The sensor is connected to a telephone line, and makes use of a current from the 'tip' and 'ring' lines of the telephone connection to supplement the power of an on-board battery. The sensor has multiple reed switches each in a different relative position. The reed switches thus each close when the magnet is in a different position, and thereby close when the fluid in the tank is at a different level. The controller has a sampling routine which responds to the detection of a closure of one of the switches by seizing the telephone line, dialing a central monitoring location and transmitting information to the central location indicating which of the switches was closed. A memory unit is provided in which multiple telephone numbers are stored so that the controller can call a second number when no response is received using a first number.

Residential fuel oil tank level reporting device

A fail safe output stage for a tank fluid level detection circuit having power supply/output leads periodically places a shunt across the leads to periodically generate a LOW signal which alternates with a HIGH signal to indicate an underfilled condition. In a filled condition, a steady signal appears across the leads. The output stage of the detection circuit consists of a parallel connection of switching devices where the 'on' impedance of any single switching device is insufficient to place the detection circuit output lead in a LOW logic state. Therefore, in a condition where one of the switching devices fails, the detection circuit output may continue to alternate, but the alternating output is not recognized as such by a disable circuit which does not detect a LOW logic condition on the output lead. Accordingly, the failed output is interpreted as an filled condition, resulting in a shutdown of the system.

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W. Somerville, MA, United States of America

Arthur W Shea