Significance and Use
4.1 Vapor pressure is an important specification property of commercial propane, special duty propane, propane/butane mixtures, and commercial butane that assures adequate vaporization, safety, and compatibility with commercial appliances. Relative density, while not a specification criterion, is necessary for determination of filling densities and custody transfer. The motor octane number (MON) is useful in determining the products' suitability as a fuel for internal combustion engines.
1. Scope
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-GasesA | 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 |
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.
2. Referenced Documents (purchase separately) 
The documents listed below are referenced within the subject standard but are not provided as part of the standard.
ASTM Standards
D1267 Test Method for Gage Vapor Pressure of Liquefied Petroleum (LP) Gases (LP-Gas Method)
D1657 Test Method for Density or Relative Density of Light Hydrocarbons by Pressure Hydrometer
D1835 Specification for Liquefied Petroleum (LP) Gases
D2158 Test Method for Residues in Liquefied Petroleum (LP) Gases
D2163 Test Method for Analysis of Liquefied Petroleum (LP) Gases and Propene Concentrates by Gas Chromatography
D2421 Practice for Interconversion of Analysis of C5 and Lighter Hydrocarbons to Gas-Volume, Liquid-Volume, or Mass Basis
Keywords
butane; calculated physical properties; liquefied petroleum gases; motor octane number; propane; relative density; vapor pressure;
ICS Code
ICS Number Code 75.160.30 (Gaseous fuels)
DOI: 10.1520/D2598-12
ASTM International is a member of CrossRef.
Citing ASTM Standards
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