New absolute pressure standard in the range 1 Pa to 7 kPa

Abstract

A new standard has been developed from the FRS4 piston gauge that was presented at the Second International Seminar organized by the Consultative Committee for Mass and Related Quantities (CCM), Paris, 1993. This instrument extends the range of absolute pressure normally achieved with pressure balances below the minimum 1.5 kPa. It offers improved uncertainties over series expansion calibration systems down to pressures of a few pascals. It also has a continuously variable output pressure, which provides very rapid calibrations. The vacuum FRS4 has a large area piston attached to an electronic balance and held centrally in the cylinder by flexure hinges. The resolution is 2 × 10 -3 Pa from 0 kPa to 2 kPa and 2 × 10 -2 Pa to 7 kPa. The reference pressure under the piston is maintained with a hybrid turbomolecular and triple section drag pump. It should be noted that in the FRS4 the reference pressure is under the piston rather than above as it is with normal piston gauges. The gas flowing down the gap between the piston and cylinder is pumped from the gap before it reaches the base of the piston by the intermediate stage of the hybrid pump operating in a split-flow mode. This allows the reference pressure to be held at 1 × 10 -3 Pa or better for the lower pressures in the measurement range and not more than 1 × 10 -2 Pa above 2 kPa. The instrument is readily transportable and should offer a level of reproducibility of 0.01% of reading or better plus a few millipascals, which, until now, has not been available except in a few highly specialized and definitely non-portable instruments.

Cite this work

No public copy is stored for this record, so only the metadata is cited.

Stored only when both papers are in the corpus — 21 citations exist upstream.