Abstract
Describes the results of a comparison of pressure measurement between NPL and PTB using transfer pressure standards over the range of nominal applied pressure 0.4-4.0 MPa, carried out in October 1986 at the National Physical Laboratory, New Delhi. The transfer pressure standards used during the comparison are the piston gauges, NPL-4 with a nominal effective area 8.392 196*10-6 m2 at 20 degrees C and PTB-4 with a nominal effective area 98.049 02*10-6 m2 at 20 degrees C. The comparison data thus obtained are analysed in terms of the accuracy achieved in the determination of the effective area of the piston gauges used. The effective area obtained for NPL-4 from the NPL main standard agrees with 1 p.p.m. with the value derived from the calibration using the PTB-4 standard. The mean value of the deviation of the pressure is 8 p.p.m., which is considered to be in good agreement within the uncertainty statement of the respective standards as deduced from the primary standards. Also determined are the zero-pressure values of the effective area of the NPL-8 reference standard by comparing it with NPL-4 and PTB-4 transfer standards. The consistency of the results clearly indicates that the measurements taken by using the calibration data for the transfer pressure standards NPL-4 and PTB-4 are compatible.