Mohan, Pardeep and Kumar, Harish (2009) Static Expansion Primary Vacuum Standard – Part 1: Determination of the Volume Ratio of the Expansion Stage. MAPAN - Journal of Metrology Society of India, 24 (2). pp. 101-109. ISSN 0974-9853

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Measurement of volume ratio forms an essential part of the characterization of a static expansion system (SES) for the generation of pressures in the medium and high vacuum region. Because of the complexity of the vacuum chambers, it is not possible to determine the absolute volumes of the chambers involved. Hence an expansion process is resorted to, in which the gas enclosed in the small volume at a known pressure is allowed to expand, under isothermal conditions, into the large volume. Re accuracy of the volume ratio thus determined depends on the stability of the vacuum gauges used for the measurement of initial and the final pressures and the ambient temperature. High accuracy resonant silicon gauges (RSGs) of two different ranges, one 130 kPa full scale and the other 1 kPa full scale for measurement of the initial and final pressures are found to be useful. This, paper reports the results obtained with these RSGs for the measurement of the volume ratio of the National Physical Laboratory, India (NPLI) SES which is nominally 2820. With the use of the RSGs, and calibrated platinum resistance thermometers (PRTs) mounted inside the vacuum chambers, it has been possible to measure the volume ratio within the relative expanded uncertainty (k = 2) of 0.0014. The results of the volume ratio determination exercise are given in this paper while the Part 2 of this paper will discuss the procedure for the calibration of spinning rotor gauges on the Static expansion primary standard.

Item Type: Article
Additional Information: Copyright for this article belongs to M/s Springer Verlag.
Subjects: Instruments/ Instrumentation
Depositing User: Ms Neetu Chandra
Date Deposited: 04 Oct 2012 08:18
Last Modified: 04 Oct 2012 08:18

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