Use of a calibrated leak to calibrate vacuum gauges

• Published in: Vacuum Vol. 48; no. 6; pp. 515 - 519
• Main Authors: Mohan, P, Gupta, AC
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-06-1997; Elsevier
• Subjects: Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Physics; Vacuum apparatus and techniques; Vacuum gauges; Pressure dependence; Measuring methods; Calibration; Experimental study; Leaks; Vacuum gages
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/S0042-207X(97)00021-3

A calibrated leak method is reported for calibrating a spinning rotor gauge (SRG) or a capacitance diaphragm gauge (CDG) of 133 Pa full scale range. The leak element and the gauge under test are connected to a vacuum chamber and the rise of pressure with time is monitored for a known volume. From the known leak rate and vessel volume, the gas pressure after a given time is calculated, and this is compared with the indicated pressure to find the correction factor. For the SRG, extrapolation over the pressure range of 10
−2–1 Pa allowed calculation of the gauge coefficient. The calibrations obtained were also compared with those from a static expansion method, giving an agreement of ± 1.0%. The results of the study of the behaviour of a commercial SRG over the pressure range of 1–140 Pa with three gases Ar, He and N
2, using the method are discussed together with the limitations.