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A rigorous data analysis has been carried out for various barometric pressure transmitters and sensors and vacuum gauges over a period of 8 years; it has been found that a small fraction of pressure and vacuum industries and research institutions from private and government organizations approach to National Metrology Laboratory (NMI), CSIR-NPL, for calibration of their equipment. The observation...
The present paper is an extension of our earlier series of studies carried out on technique of ultrasonic phase velocity measurement in liquid/mixtures (Joshi et al. MAPAN J Metrol Soc India 29:9–17, 2014) with modified/improved designs related to jigs and fixtures, temperature stability arrangement, improved data acquisition for digitization by using 2.5 GS/s sampling frequency. An improved...
Present paper reports the design and developmental aspects of a new technique for ultrasonic phase velocity measurement in liquids, which is based on the studies carried out on frequency dependence of ultrasonic velocity in pure, binary and ternary liquids/mixtures. The design and developmental aspects of the experimental set up are reported along with optimisation of data acquisition software developed...
We report the performance of calibration laboratories in the pneumatic pressure region (0 to 5) MPa through a recently conducted inter-laboratory comparison. Six NABL (National Accreditation Board for Testing and Calibration Laboratories) accredited laboratories participated in the program. The proficiency testing program was organized and piloted by CSIR-National Physical Laboratory. The program...
Measurement of acoustic impedance requires both the measurement of ultrasonic velocity as well as density. The present work is an extension of our previous novel method reported and validated through a series of acoustic impedance studies carried out in a number of pure, binary and ternary liquid mixtures. To bypass the ambiguity of measurement of velocity and density independently, and to overcome...
The current paper reports the stability of a pressure dynamometer with a full scale pressure of 60 bar over nine years of operation. Since the stability of this digital pressure gauge depends on factors like repeatability, hysteresis, non-linearity, relative deviation etc, a systematic study has been carried out on each of these components. Finally, a comparison of the calibration factors and the...
For the first time a novel experimental technique has been used for direct evaluation of acoustic impedance of liquids. Till date researchers have been using ultrasonic velocity and density measurements to compute acoustic impedance and thermodynamic parameters, which are then used to investigate the nature of molecular interactions of solvent molecules in binary, ternary and quaternary liquid mixtures...
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