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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...
The main factor to affect lower limit of static expansion vacuum standard is outgassing of the inner surface. A new method has been demonstrated to extend the lower limit by using a non-evaporable getter pump (NEGP) to eliminate the outgassing influence. Because NEGP has no pumping speed for inert gases, it can maintain the ultra-high vacuum background without changing gas quantity in the calibration...
Korea Research Institute of Standards and Science (KRISS) has assembled a new flow-control system (FCS-705) for the study of advanced applications and calibration of different types of vacuum gauges by comparison method. This report details the measurement of the outgassing rate of the main vacuum chamber by the pressure rate of rise method. Constant pressure was generated inside the vacuum chamber...
This paper reports the performance of the calibration results obtained by 21 laboratories using digital pressure calibrator as an artifact in the pressure range 7–70 MPa. National Physical Laboratory (NPLI), New Delhi has coordinated this programme and also acted as a reference laboratory. The program started in May, 2006 and completed during May, 2008. The comparison was carried out at 10 equally...
The Part 1 of this paper discussed the determination of the volume ratio of the Static Expansion Primary Vacuum Standard (SES). Part 2 of the paper discusses in detail the use of the SES thus characterized for generating primary pressures. This standard has been used to calibrate Spinning Rotor Gauges (SRGs) at a number of pressures in the range 0.1 Pa to 1 Pa in steps of 0.1 Pa. The Gauge Coefficient...
This paper discusses an extended usage of conventional pressure balances for measurements of pressure down to a few Pa. Generally pressure balances are widely used as pressure standards but they have a major disadvantage, that is, their inability to operate at pressures below a limit determined by the mass of floating elements. This limit is typically around 5 kPa. Several approaches have been tried...
Accurate calibrations of gauges to ever lower pressures (higher vacuum) are increasingly becoming necessary. The calibrations over the entire ultra high vacuum (UHV) range i.e. up to 10−10 Pa are already sometimes demanded by the users of vacuum measuring devices. Standards covering part of this range are available in some national metrological laboratories while primary standards covering the entire...
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