title: A Primary Dead-Weight Tester for Pressures (0.05-1.0) MPa.
abstract: Recent advances in technology on two fronts, 1) the fabrication of large-diameter pistons and cylinders with good geometry, and 2) the ability to measure the dimensions of these components with high accuracy, have allowed dead-weight testers at the National Institute of Standards and Technology (NIST) to generate pressures that approach total relative uncertainties previously obtained only by manometers. This paper describes a 35 mm diameter piston/cylinder assembly (known within NIST as PG-39) that serves as a pressure standard in which both the piston and the cylinder have been accurately dimensioned by Physikalisch Technische Bundesanstalt (PTB). Both artifacts (piston and cylinder) appeared to be round within ±30 nm and straight within ±100 nm over a substantial fraction of their heights. Based on the diameters at 20 °C provided by PTB (±15 nm) and on the good geometry of the artifact, the relative uncertainties for the effective area were estimated to be about 2.2 × 10(-6) (1σ).
authors.affiliation: National Physical Laboratory, New Delhi, India.
authors.forename: Kamlesh
authors.initials: K
authors.lastname: Jain
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8360.
authors.forename: Walt
authors.initials: W
authors.lastname: Bowers
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8360.
authors.forename: James W
authors.initials: JW
authors.lastname: Schmidt
keywords: dead-weight tester; piston gage; piston/cylinder assembly; pressure measurement; primary pressure standards