ASTM D2598 : 12

Standard Practice for Calculation of Certain Physical Properties of Liquefied Petroleum (LP) Gases from Compositional Analysis

Standard Details

1.1 This practice covers, by compositional analysis, the approximate determination of the following physical characteristics of commercial propane, special-duty propane, commercial propane/butane mixtures, and commercial butane (covered by Specification D1835): vapor pressure, relative density, and motor octane number (MON).

1.1.1 This practice is not applicable to any product exceeding specifications for nonvolatile residues. (See Test Method D2158.)

1.1.2 For calculating motor octane number, this practice is applicable only to mixtures containing 20 % or less of propene.

1.1.3 For calculated motor octane number, this practice is based on mixtures containing only components shown in Table 1.

TABLE 1 Factors for Determining the Physical Characteristics of LP-Gases^A

Component	Vapor Pressure Blend Factor, kPa-gage (PSIG) at 37.8°C (100°F)	Relative Density at 15.6°C (60°F)	MON Blend Value
Methane	17547 (2545)	0.3	. . .
Ethane	4213 (611)	0.3563	100.7
Ethene (Ethylene)	8720 (1265)	0.37	75.6
Propane	1200 (174)	0.5072	97.1
Propene (Propylene)	1466 (213)	0.5226	84.9
Methylpropane (Isobutane)	400 (58)	0.5629	97.6
n-Butane	255 (37)	0.5842	89.6
t-2-Butene	242 (35)	0.6099	…
1-Butene	328 (48)	0.6004	80.8
2-Methylpropene (Isobutylene)	340 (49)	0.6004	…
c-2-Butene	216 (31)	0.6275	83.5
2,2-Dimethylpropane (Neopentane)	152 (22)	0.5961	80.2
Cyclopentane	-33 (-4.7)	0.7503	84.9
2-Methylbutane (Isopentane)	40 (5.8)	0.6251	90.3
n-Pentane	6.4 (0.9)	0.6307	62.6
n-Hexane	-67 (-9.7)	0.6641	26.0

^A Some constants for vapor pressure and motor octanes are empirical values to be used only in the calculation procedures described in this practice. References are located in Appendix X1.

1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.

1.2.1 Exception—Motor octane number and relative density are given in MON numbers and dimensionless units, respectively.