This report outlines a method for the calculation of the speed of sound in natural gas and the individual components that make up natural gas. It calculates the entropy, enthalpy and C* coefficient for the sonic nozzels. This information is based on research that was developed and managed by the Gas Technology Institute (formerly the Gas Research Institute). The research indicates that the calculation is highly accurate and is consistent with the equation-of-state used in the AGA Report No.8, Compressibility Factors of Natural Gas and Other Related Hydrocarbon Gases. The original work for AGA Report No.8 was developed under the auspices of the Gas Research Institute's Basic Fluid Properties Research Program, the AGA Transmission Measurement Committee, the Gas European de Research Group (GERG), members of the American Petroleum Institute (API) and the International Standards Organization (ISO).

References
American Gas Association Report No.10, 2003, Speed of Sound in natural gases and other related hydrocarbon gases