Report EURAMET.M.P-S9 / EURAMET 1170 FINAL REPORT, Version 6 of 2016-12-22 1 EURAMET.M.P-S9 / EURAMET 1170, LOOP2 Comparison in the negative gauge pressure range -950 to 0 hPa FINAL REPORT P. Otal 1 , F. Boineau 1 , N. Medina 2 , D. Pražák 3 , C. Wüthrich 4 , S. Saxholm 5 , W. Sabuga 6 , I. Kocas 7 , Y. Durgut 7 ABSTRACT This report gives the results of a comparison of pressure standards of seven European National Metrology institutes in the range of negative gauge pressure from -950 hPa to 0 hPa. This comparison was piloted by LNE and was carried out from January 2011 to March 2012. This work is a part of the EURAMET project 1170 and is registered as a supplementary comparison EURAMET.M.P-S9. The transfer standard used was a pressure monitor RPM4 A160Ks manufactured by DH Instruments Inc, with a resolution of 0.1 Pa. The reference values have been determined from the weighted mean of the deviations reported by the participants for each specified pressure. Seventy three of the seventy seven values (96%) reported by the laboratories agree with the reference values within the expanded uncertainties with a coverage factor k = 2. 1 Laboratoire National de Métrologie et d'Essais, France (LNE) 2 Centro Español de Metrología, Spain (CEM) 3 Czech metrology institute, Czech Republic (CMI) 4 Bundesamt für Metrologie, Switzerland (METAS) 5 Centre for metrology and accreditation, Finland (MIKES) 6 Physikalisch-Technische Bundesanstalt, Germany (PTB) 7 Ulusal Metroloji Enstitüsü, Turkey (UME)