Different long-term characteristics of hydraulic pressure gauges under constant pressure applications

Abstract

This article focuses on the long-term drifts of hydraulic pressure gauges, which are constantly subjected to high pressures. A target measurement pressure was consistently applied to pressure gauges for more than two months, and the gauges were occasionally calibrated against a reference pressure balance. The long-term drift has been evaluated based on the variations in calibration values with the elapsed time since the pressure application. We evaluated the long-term drift of three kinds of pressure gauges that are commonly used for calibrations and industrial measurements. The long-term drift differed depending on the type of sensing structure. Although the gauges that had similar sensing structures showed similar drift when the gauges were pressurised due to atmospheric pressure, the amount of the drift depended on each product. In addition, the long-term drift was also affected significantly by the preliminary pressure conditions, even under the same pressure application. Preliminary or ex-post evaluations are necessary for the respective gauges under similar pressure conditions. In practice, the drift of zero-reading is often the main contributory factor of the drift; therefore, the drift can be mitigated by tracing the zero-reading during the pressure applications.