Abstract: Direction of travel from a wave front in a pipeline is determined with two pressure sensors spaced relatively near to each other so that the site from which the wave front emanated is not located therebetween. For each sensor, a determination is made as to whether a detected signal has exceeded a negative or a positive threshold. In addition, the sensor outputs are subtracted from each other to determine which sensor detected the wave front first. Combining the resulting signals yields information on the nature of the wave front and its direction of travel.

Abstract: A self-calibrating temperature sensing probe having a temperature sensor positioned adjacent to a vial of a predetermined substance in an isothermal environment created by a housing and insulation. A heating element is positioned about the vial to effect vial heating. The substance is preselected for its melting point temperature, which is in excess of the ambient temperature of the environment surrounding the housing. During recalibration the substance is heated above its melting point and allowed to cool. During cooling the temperature of the substance is recorded and the liquid-to-solid phase change determined. Recalibration is affected using the phase change temperature of the substance as a calibration point.