Abstract: A non-contact caliper-type gauge particularly suited for measuring the thickness of a running web. In its preferred form, the system includes a pair of opposed scanning heads defining a gap through which the running web passes, the heads being adapted to transverse across the width of the running web. Each of the heads includes and ultrasonic transducer for directing energy at the web, detecting energy reflected from the face of the web nearest the respective transducer and determining the distance between a reference in the head and the facing surface of the web. One of the heads also includes a transducer, preferably an eddy current transducer, which operates on energy to which the web is transparent. The second transducer senses the distance between the heads thereby to determine any variations in the distance between the heads during traverse.

Abstract: A pass-line independent measuring device for producing thickness related measurements (e.g., thickness, basis weight, density, etc.) of a moving web. The thickness measurements themselves are based on a nuclear source and detector mounted on one or both sides of the web, the source emitting radiation and the detector detecting emitted radiation from the web as an uncorrected measure of web thickness. An ultrasonic distance measuring means is fixedly associated with either the source, the detector, or both and continuously directs ultrasonic pulses in a direct path to the web, measures reflections in substantially a similar direct path, and by means of the time delay between a pulse and its reflection determines the actual pass-line of the web between the source and detector. The pass-line is used with a correcting function to correct the nuclear readings and provide a substantially accurate measure of web thickness corrected for pass-line.

Abstract: An oxygen sensing probe of the type in which a sensor tip made of a solid electrolyte is secured within a supporting tube by an hermetic seal. The tip is made of yttria-stabilized zirconia; the tube is made of magnesium-aluminate spinel, calcia and zirconia; and the tip and the tube are bonded together by a fusion weld consisting of a eutectic mixture of the tip material and the tube material. The coefficient of thermal expansion of the tube material very closely matches that of the tip material so as to prevent the seal from cracking when the probe is cycled rapidly and repeatedly through a wide temperature range. A frustoconical shoulder on the sensor tip engages a slotted frustoconical seat within a tubular outer conductor to establish good electrical contact between the tip and the electrode while allowing gas to circulate freely past the tip.