Extension of the application range of a piston pressure gauge to low pressures

Abstract

A method is presented by which a absolute pressure gauge may be calibrated using a single piston gauge in a pressure range more than two decades lower than its usual working range. The calibration pressure is referenced to the weight of an additional mass and to the cross section of the piston. The auxiliary instrumentation necessary for this method is an uncalibrated reference pressure gauge and a mechanism for removing the additional mass from the piston. A measurement uncertainty of +or-0.6 Pa down to a pressure of 30 Pa has been achieved. From a test measurement it is inferred that the absence of a finite bell jar pressure in a piston gauge does not influence its operation.