1.1 This test method describes the calculation of true vapor pressures of petroleum distillate fuels for which distillation data may be obtained in accordance with Test Method D86 without reaching a decomposition point prior to obtaining 90 volume% distilled.

1.2 The test method may be used to calculate vapor pressures at temperatures between the 0% equilibrium flash temperature and the critical temperature of the fuel. Provision is included for obtaining a calculated critical temperature for fuels for which it is not known.

1.3 Critical pressure-temperature data are usually not available for petroleum fuels. However, if both the critical pressure and critical temperature are known, the values shall be used as the coordinates in Fig. 3 to establish a critical point to be used instead of the focal point established as described in 6.5.4; and the calculations described in 6.5 through 6.5.4 are not required. If either a determined true boiling point or determined equilibrium flash vaporization temperature at 0% distilled at atmospheric pressure is known, the determined value shall be used to establish the lower limit of the bubble-point line referred to in 6.4.

1.4 The method is not reliable for distillate fuels having a boiling range of less than 100°F (38°C) between the Test Method D86 10 and 90 volume% distilled temperatures.

1.5 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.