Creation of a National Primary Standard for the Unit of Pressure in the Range of 10–1600 MPa

Characteristic analysis of a controlled-clearance piston-cylinder assembly up to 1500 MPa using a finite element method

“…where A 0 is the effective area at zero pressure, and λ is the elastic distortion coefficient. For accurate measurement of high pressures and ultra-high pressures, controlled-clearance (CC) piston gauges are adopted as national primary standards by many countries [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], with upper limits from 280 MPa to 2600 MPa. Compared to simple piston gauges whose cylinders can deformed freely, a CC piston gauge has an individually controlled jacket pressure p j applied on the cylinder's outer surface to reduce clearance between the piston and the cylinder under high pressure, avoiding deviation from the essential hydro-static equilibrium for pressure measurement due to excessive fluid leaking or piston falling.…”

Elastic Distortion Calculation of a Controlled-Clearance Piston-Cylinder Assembly up to 1500 MPa Using Finite Element Method

“…For high pressure or ultra-high pressure (no strict definition, usually above 150 MPa), additional jacket pressure surrounding the outer surface of cylinder is needed to reduce the clearance between piston and cylinder avoiding measurement failure due to excessive piston fall speed. Such controlled-clearance (CC) type of piston gauge was first proposed by Johnson and Newhall [1] and has been widely accepted and used by national metrology institutes [2][3][4]. It has been intensively studied in the past using various techniques [4][5][6][7][8][9][10][11][12][13][14][15].…”