This document contains information for computation of sound speed in natural gas and other related hydrocarbon gases. Procedures are included for computation of several related gas properties, including heat capacity, enthalpy, entropy and the critical flow coefficient, C*.

The methods in this document are extensions to Compressibility Factors for Natural Gas and Other Hydrocarbon Gases, AGA Transmission Measurement Committee Report No. 8, Second Edition, Second Printing (1994). This document contains excerpts from Report No. 8, but intentionally does not reproduce the full report.

Similarly, the methods for computing the critical flow coefficient, C*, are based on the information in appendix E of ASME/ANSI MFC-7M-1987. Users are referred to this source for background and pertinent references.

Procedures for computing other natural gas properties, such as volumetric heating value and relative density, fall outside of the scope of this report and are not included.