Improved Measurement Capabilities in Pneumatic Pressure Measurements at NPLI Through Re-establishment of the Traceability Chain

This work presents, in brief, the recently concluded extensive in-house inter-comparison of the pneumatic pressure standards at CSIR-National Physical Laboratory, India (NPLI) and the resulting marginal improvement in our measurement uncertainties. The measurements are traceable to the Ultrasonic interferometer manometer (UIM), our low-pressure primary pressure standard as well as to the national primary standard in pneumatic pressure, NPLI-P1. The inter-comparisons and the subsequent estimations of measurement uncertainties, starting from the UIM, were carried out in the overlapping pressures, ranging from 0.01 to 40 MPa. In addition, the large-diameter piston gauge, the pneumatic primary standard was also used to establish the traceability chain. A summarized description of the extensive exercise undertaken is given herein which describes the stability and the excellent agreement with previously reported results as well as successful improvement owing to better control over experimentation as well as environmental factors.