Значение и использование

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.

Область применения

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.