Int J Thermophys (2011) 32:1111–1124 DOI 10.1007/s10765-011-0999-6 A Capillary Tube Viscometer Designed for Measurements of Hydrogen Gas Viscosity at High Pressure and High Temperature Elin Yusibani · Yosuke Nagahama · Masamichi Kohno · Yasuyuki Takata · Peter L. Woodfield · Kanei Shinzato · Motoo Fujii Received: 2 April 2010 / Accepted: 3 May 2011 / Published online: 17 May 2011 © Springer Science+Business Media, LLC 2011 Abstract A capillary tube viscometer was developed to measure the dynamic viscosity of gases for high pressure and high temperature. The apparatus is simple and designed for safe-handling operation. The gas was supplied to the capillary tube from a high-pressure reservoir tank through a pressure regulator unit to maintain a steady state flow. The measurements of a pressure drop across the capillary tube with high accuracy under extreme conditions are the main challenge for this method. A differential pressure sensor for high pressures up to 100MPa is not available com- mercially. Therefore, a pair of accurate absolute pressure transducers was used as a differential pressure sensor. Then the pressure drop was calculated by subtracting the outlet pressure from the inlet one with a resolution of 100 Pa at 100 MPa. The accuracy of the present measurement system is confirmed by measuring the viscosity of nitrogen as a reference gas. The apparatus provided viscosities of nitrogen from ambient temperature to 500 K and hydrogen from ambient temperature to 400 K and E. Yusibani · Y. Nagahama · M. Kohno · Y. Takata Department of Mechanical Engineering, Kyushu University, Fukuoka, Japan E. Yusibani (B ) · M. Kohno · Y. Takata · K. Shinzato · M. Fujii Research Center for Hydrogen Industrial Use and Storage (HYDROGENIUS-AIST), 744 Motooka, Nishiku, Fukuoka, Japan e-mail: e-yusibani@aist.go.jp P. L. Woodfield School of Engineering, Griffith University, Nathan, Australia E. Yusibani Physics Department, Universitas Syiah Kuala, Banda Aceh, Indonesia M. Kohno · Y. Takata International Institute for Carbon-Neutral Energy Research (I 2 CNER), Kyushu University, Fukuoka, Japan 123