Proceedings of the 1 st Annual Gas Processing Symposium H. Alfadala, G.V. Rex Reklaitis and M.M. El-Halwagi (Editors) © 2009 Elsevier B.V. All rights reserved. 1 Wide Range, High Accuracy PρT Measurements by Single Sinker Magnetic Suspension Densimeter for Natural Gas-Like Mixtures M. Atilhan a , P.V. Patil b , S. Ejaz c , D. Cristancho d , J. Holste e and K.R. Hall d a Qatar University, Chemical Engineering Department, Doha, Qatar, 2713 b S&B Engineering, Houston, TX c ABB International, Houston, TX d Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, 77843 e Texas A&M Univeristy at Qatar, Doha, Qatar Abstract High-accuracy density measurement data are necessary to validate equations of state (EOS) used in natural gas transport. The American Gas Association (AGA) AGA8- DC92 EOS, currently the industry standard, has been validated against a databank of gas mixtures with compositions containing up to 0.2 mole percent of the C 6+ fraction and should predict densities of natural gas mixtures containing higher mole percentages of the C 6+ fraction with the same accuracy. Several attempts have been made to develop a new EOS that can serve the gas industry because the reliabilibity of AGA8-DC92 has been criticized over the past years. One of the biggest reasons that academia seeks opportunities to develop new EOS is the need to express the PρT behaviour of natural gas mixtures that contain heavy components in larger fractions than AGA8-DC92 can handle. Production of natural gas streams containing higher percentages of the C 6+ fraction has begun recently in North America. High-accuracy, density data for such natural gas mixtures are necessary to check the ability of AGA8-DC92 to cover the entire range of pressure, temperature and compositions encountered in custody transfer. Therefore, this work reveals the ability of the AGA8-DC92 to predict the densities of such mixtures. A state-of-the-art, high pressure, high temperature, compact single- sinker magnetic suspension densimeter has been used to collect densities of simulated natural gas mixtures having several different methane compositions after validating the densimeters operation by measuring densities of pure argon, nitrogen and methane in the range 270 to 340 K and 3.5 to 35 MPa. Based upon the measurements, temperatures were within ±3.8 mK, pressures had an uncertainty of 0.002 %, the weighing balance readings for the true mass of the sinker in vacuum had an uncertainty of 0.01 mg and the weighing balance readings for the apparent mass sinker under pressure had an uncertainty of 0.02 mg. The measured data indicate the advisability of performing an extensive study of AGA8-DC92 for natural gas mixtures. Keywords: Multicomponent mixtures; Natural gas; Phase equilibria; Isochoric; Densimeter; Magnetic Suspension; Isochoric; Equations of state.