A New Semi-Automated System for the Determination of Effective Area of Ruska/Fluke Calibration 246X Piston-Cylinders

Abstract

Model 2465 and 2468 Piston Gauges are used to disseminate traceability in gas pressure at a very low uncertainty for various applications in a range of 1.4 to 7000 kPa in gauge or absolute modes. The most important and the most difficult metrological characteristic to determine is the effective area of the piston-cylinder, the primary measuring element of a piston gauge. The process to determine effective area, called crossfloating, can be time consuming and subject to influences by the personnel performing the work if done manually. The Fluke Calibration Primary Pressure and Flow Laboratory supports the effective area determination of over 200 of these piston-cylinders each year. These crossfloats can take up to eight hours to perform depending on the range. In June of 2016 efforts were taken by the Fluke Calibration Phoenix team to completely redesign the cross float bench for these piston-cylinders to improve process time without degradation of results. The intent was to design a system similar to the technology developed by Fluke Calibration in 2008 for a fully automated crossfloat system for a different model, but with some limitations on automation. The result was better than what was expected. This paper discusses the design of the crossfloat system, the methods used to validate the new process, and a compilation of the overall results.