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    Vacuum Science & Technology Thursday Sessions
       Session VST1-ThP

Paper VST1-ThP10
A Compact Leak Rate Calibration System

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Pressure Measurement & Calibration Poster Session
Presenter: X. Chen, Tsinghua University, P.R. China
Authors: X. Chen, Tsinghua University, P.R. China
Q. Zhang, Tsinghua University, P.R. China
Q. Liu, Tsinghua University, P.R. China
F. Yang, Tsinghua University, P.R. China
L. Cha, Tsinghua University, P.R. China
Correspondent: Click to Email
A compact leak rate calibration system has been developed to meet the quality control of industrial leak detection, especially the growing needs of sniffing application. It was designed to calibrate the leak rate from high pressure to atmosphere (pressure leak), but can be used for vacuum leak (from atmosphere to vacuum) rate calibration also. A new method based on constant volume change in pressure for pressure leak rate calibration has been put forward. A differential capacitance diaphragm gauge (CDG) has been selected to decrease the temperature effect greatly. The system consists of a calibration unit and a computer. All of the data could be collected and processed automatically. A mechanical pump has to be added if the system is used for calibrating vacuum leak rate. The whole size of the calibration unit is 30 X 20 X 20 cm@super 3@ only. The main parts of the calibration unit are: 1. a reference chamber with a valve connected to atmosphere or a vacuum pump; 2. a calibration chamber with a valve connected with the calibrated leak; 3. a differential CDG; 4. an isolate valve between the above two chambers for pressure balance before calibration or turn on the test, the total valium of the reference region has been pre-calibrated and the calibration region including the outlet of the test leak can be calibrated by the system itself; 5. a temperature monitor unit; 6. an heat isolator system. It was proven that 1 X 10@super -5@ Pam@super 3@/s pressure leak rate at room temperature could be calibrated with an accuracy of better than ±5% ( the confidential index is 95% ) and the minimum pressure leak rate could be calibrated was 3 X 10@super -6@ Pam@super 3@/s with an accuracy of better than ±15% , when the environmental temperature change was within ±0.1°C. The total test period was about 30 minutes. The system is compact and suitable for leak rate calibration in industry.