AN OLD INSTRUMENT IN THE NEW TECHNOLOGICAL SCENERY - THE PISTON GAUGEIN LIQUID-MEDIA UP TO 1 GPA

A brief historical review, beginning from the first half of the ninete enth century, illustrates the fundamental steps in the development of piston gauges for precise pressure measurements, which were stimulated by the growth of the steam industry and, generally, by hydraulic appl ications. The main different operational principles and methods for pi ston gauge characterization are reviewed and the state of the art is d iscussed from the standpoint of the achievement of the lowest possible measurement uncertainty. An analysis is made of the principal current research problems which are: (i) accurate determination of the effect ive area of piston-cylinder units at pressures up to several gigapasca ls; (ii) elastic distortion of piston-cylinder units as a function of applied pressure. This analysis may be a basis for future research wor k, with a view to acquiring better knowledge of the parameters which l imit the accuracy of pressure measurements. Possibilities for the use of modem piston gauges in liquid media to pressures of gigapascal orde r are summarized.