Using a high-resolution pressure transducer,an automated calibration system for hydraulic piston gauges in the range of 1～120 MPa has been developed based on the theoretical analysis,manifold design and programming.The transducers'linear coefficients and its long-term stability were tested,and the results showed that the deviations of linear coefficients from 1 were less than±4×10-4.Comparing with the traditional calibration method,the reliability of the developed system for the dissemination of pressure SI-unit from the NIM primary pressure standard has been demonstrated.The calibration results by two methods,the so-called Δp-method and p-method,were compared using the automated system,and the consistency of the two methods was verified.By using the automated system for the calibration of hydraulic piston gauges,the relative expanded uncertainty of the calibrated effective area is 32×10-6(k=2),and the expanded uncertainty of the calibrated distortion coefficient is 1.8×10-7/MPa(k=2).The time required for calibration is significantly reduced compared to traditional methods.
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