AVS 59th Annual International Symposium and Exhibition
    Vacuum Technology Tuesday Sessions
       Session VT-TuP

Paper VT-TuP5
A Calibration System for Helium Leak Calibrator

Tuesday, October 30, 2012, 6:00 pm, Room Central Hall

Session: Vacuum Technology Poster Session and Student-built Vacuum System Poster Competition
Presenter: Y.-W. Lin, Instrument Technology Research Center, Taiwan
Authors: Y.-W. Lin, Instrument Technology Research Center, Taiwan
C.-C. Hung, Instrument Technology Research Center, Taiwan
C.-P. Lin, Instrument Technology Research Center, Taiwan
C.-N. Hsiao, Instrument Technology Research Center, Taiwan
F.-Z. Chen, Instrument Technology Research Center, Taiwan
Correspondent: Click to Email
A calibration system for helium leak calibrator was developed, and the measurement uncertainty associated with the system. The design of the system took into consideration of influencing factors that include reference standard leak calibrator (ref.), leak calibrator under testing (dut.), vacuum chamber, He leak detector, I/O interface, and computer control. The system operates referring the standard test method for calibration of helium leak detectors by use of secondary standards (ASTM F78). This reference standard leak calibrator (ref.) was calibrated near 23℃ by comparison with Flowmeter of the national institute standards and technology (NIST) primary Leak Standard, using a combination of direct flow and upper to lower chamber flow division technique. The present estimate of the total uncertainty in the measured leak rate of this artifact at 23℃ at the time of test is 5.2%. This includes a systematic uncertainty of 2.0% in Flowmeter of the NIST primary Leak standard and 3.2% random errors in the measured leak rate of this artifact. The errors represent three standard deviations. In order to optimize the overall accuracy in the use of this artifact, it should be stored with any shutoff valve open (a dust cover can be used to protect the vacuum port). The leak artifact should be stored at the temperature at which it will be used for at least 24 hours and pumped for least 3 hours prior to use. Sufficient time should also be allowed for the system on which the leak artifact is to be used to come to equilibrium with 0 the environment. The present research has demonstrated the high stability of the calibration system for helium leak calibrator, and its capabilities of conducting calibration for helium leak calibrator with great efficacy.