A reliable quartz digital transfer pressure standard for high pressure measurements upto 275 MPa

摘要

The piston gauges are the primary and reliable instruments used for high pressure measurement upto 1.4 GPa. For the measurement of pressure beyond 200 MPa, the bulky sizes, high costs. highly skilled operations and difficulties in transportation of the piston gauges limit their use in National Metrological laboratories and Reference Pressure Laboratories. The use of pressure transducers as transfer standards may overcome such difficulties. The present paper describes the characterization of one such quartz digital pressure transducer to measure high hydrostatic pressure upto 2750 bar or 275 MPa. Metrological characteristics thus studied include repeatability, linearity, sensitivity, hysteresis and measurement uncertainty. This commercially available digiquartz pressure transducer studied in the present work is based ml the principle of detecting pressure-induced stress by means of changes in the oscillating frequency of the crystalline-quartz resonator. This evaluation of transducer reveals that it had a maximum hysteresis of 0.02% of reading. However, the repeatability of the transducer was found to be excellent which is less than 0.01%. The standard uncertainty components U{sub}(type-A) and U{sub}(type-B), evaluated through Type A and Type B evaluations of measurement uncertainty, are estimated to be ±0.0222 MPa and ±0.045 MPa, respectively. The overall standard uncertainty associated with the measurements is found to be less than 0.07 MPa at coverage factor of k=2. This suggests that such transducers can be used as transfer standards to check the performance of pressure balances to measure accurate pressure and to calibrate pressure measuring equipments in the pressure range upto 275 MPa.