IR vs Nuclear Fiber Weight Measurement • Field Trial Results on Tissue, 2012 PaperCon Conference
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The results of a trial comparing the performance of a nuclear sensor and an infrared (IR) transmission sensor in measuring the fiber weight on tissue are presented. The traditional gauging solution in tissue employs a beta-emitting nuclear source to measure the total basis weight, together with an IR transmission sensor to measure the basis weight of water. These two measurements are typically combined to provide online measurements of basis weight and percent moisture. A trial was conducted on a conventional tissue machine, deploying this traditional arrangement simultaneously with an IR transmission sensor capable of measuring both basis weight and percent moisture, directly. The tissue machine on which the trial was conducted produces a variety of non-ash-containing tissue grades ranging from 15 to 45 g/m2 in basis weight, and 3 to 4 percent moisture at the reel. A quality control system provides machine-direction control of both basis weight (using the stock flow valve) and moisture (using the Yankee hood temperature). In this paper, the measurement profiles and the average trend values of the two measurement technologies are compared, and control trial results are presented. Some of the key performance differences between the two gauging solutions are discussed. The IR fiber weight measurement is found to correlate very well with the nuclear and the lab measurements. The IR measurement shows a high signal-to-noise ratio, good stability, and is insensitive to certain environmental influences that can compromise the accuracy of the nuclear basis weight measurements.