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Session:
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1B - Temperature I
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Date & Time:
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Monday August 7, 10:45 AM - 12:15 PM
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Paper Title:
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Improvement Study on the Use of Dry-Well Calibrators for PRT calibration
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Speaker:
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Mingjian Zhao, Director of Primary Satndard Engineering
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CoAuthors:
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Mike Hirst, Rong Ding, and Deming Chen
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Speaker Info
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Company:
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Fluke-Hart Scientific
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Address:
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799 E Utah Valley Dr.
American Fork, UT, 84003-9775, United States
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Phone:
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801-763-1600
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Fax:
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801-763-1010
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Email:
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mingjian.zhao@hartscientiific.com
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Abstract:
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Dry-well block calibrators are widely used as temperature standards or comparison apparatus in many secondary level calibration laboratories and in various industrial fields. Since dry-well (dry-block) calibrators are designed primarily for convenience and efficiency in a calibration process, a few inherent limitations are inevitable. In order to reduce calibration errors and improve the performance of dry-well calibrators, a new dry-well calibrator with dual-zone control was developed at Fluke Hart Scientific. The performance of the new dual-zone dry-well was evaluated. Horizontal and vertical temperature gradients in the block and stability and hysteresis of the control sensor are main deficiencies that affect the performance of dry-well calibrators. These characteristics were measured using a specially made platinum resistance thermometer. The special PRT has a very short sensor within a platinum capsule, but no sheath. It is an excellent probe for measuring vertical temperature gradients. The design of this PRT will be described briefly. Besides the inherent deficiencies of dry-well calibrators, correct use is also very critical to minimize calibration errors. Some common operational mistakes and measurement errors will be discussed. Based on the test results, a few methods to reduce the measurement errors will be introduced. Several PRTs with different structures were calibrated at fixed points and then tested in the dual-zone drywell to identify measurement errors. The results will be reported.
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