Final Report on APMP.M.P-S7.TRI May 2017 The Asia-Pacific Metrology Programme (APMP) 200 MPa HYDRAULIC PRESSURE INTERLABORATORY COMPARISON Final Report on Supplementary Comparison APMP.M.P-S7.TRI in Hydraulic Gauge Pressure from 40 MPa to 200 MPa November 2016 Tokihiko Kobata 1 , Douglas A Olson 2 , and Alaaeldin A Eltawil 3 Abstract This report describes the results of a supplementary comparison of hydraulic high-pressure standards at three National Metrology Institutes (NMIs), National Metrology Institute of Japan, AIST (NMIJ/AIST), National Institute of Standards and Technology (NIST), USA and National Institute for Standards (NIS), Egypt, which was carried out at NIST during the period May 2001 to September 2001 within the framework of the Asia-Pacific Metrology Programme (APMP) in order to evaluate their degrees of equivalence at pressures in the range 40 MPa to 200 MPa for gauge mode. The pilot institute was NMIJ/AIST. Three working pressure standards from the institutes, in the form of piston-cylinder assemblies, were used for the comparison. The comparison and calculation methods used are discussed in this report. From the cross-float measurements, the differences between the working pressure standards of each institute were examined through an evaluation of the effective area of each piston-cylinder assembly with its uncertainty. From the comparison results, it was revealed that the values claimed by the participating institutes, NMIJ, NIST, and NIS, agree within the expanded (k = 2) uncertainties. The hydraulic pressure standards in the range 40 MPa to 200 MPa for gauge mode of the three participating NMIs were found to be equivalent within their claimed uncertainties. 1 NMIJ/AIST: National Metrology Institute of Japan, AIST, AIST Tsukuba, Ibaraki, Japan. 2 NIST: National Institute of Standards and Technology, Gaithersburg, MD, USA 3 NIS: National Institute for Standards, El-Haram, Giza, Egypt