AN INTERCOMPARISON BETWEEN NPL (INDIA) AND NIST (USA) PRESSURE STANDARDS IN THE HYDRAULIC PRESSURE REGION UP TO 26 MPA

Results are presented of an intercomparison of pressure measurements b etween the National Physical Laboratory (NPL), India, and the National Institute of Standards and Technology (NIST), USA, using piston gauge pressure standards over the range 6 MPa to 26 MPa. The intercompariso n, using the NPL piston gauge pressure standard, with a nominal effect ive area of 8.4 x 10(-5) m2, and the NIST piston gauge pressure standa rd, with a nominal effective area of 2.0 x 10(-5) m2, was carried out at the NPL. The intercomparison data obtained show a relative differen ce of 1 x 10(-6) in the zero-pressure effective area (A0) of the NPL s tandard as obtained by the NIST standard. At 6 MPa the relative differ ence in effective areas is 3.5 x 10(-6); at the full scale pressure of 26 MPa, the relative difference is 12x10(-6). These differences are i n excellent agreement with the statements of uncertainty of the respec tive standards as obtained from the primary standards of these two lab oratories.