1.1 This practice covers, by compositional analysis, the approximate determination of the following physical characteristics of commercial propane and special-duty propane (covered by Specification D 1835): vapor pressure, relative density, and motor octane number (MON). 1.2 This practice is not applicable to any product exceeding specifications for nonvolatile residues. (See Test Method D 2158.) 1.3 For calculating motor octane number, this practice is applicable only to mixtures containing 20 % or less of propene. 1.4 For calculated motor octane number in method, this practice is based on mixtures containing only components shown in Table 1. 1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.