Full Description

1.1This test method describes procedures for measuring the vapor pressure of pure liquid or solid compounds. No single technique is able to measure vapor pressures from 110¹¹ to 100 kPa (approximately 10¹⁰ to 760 torr). The subject of this standard is gas saturation which is capable of measuring vapor pressures from 110^-11 to 1 kPa (approximately 10^-10 to 10 torr). Other methods, such as isoteniscope and differential scanning calorimetry (DSC) are suitable for measuring vapor pressures above 0.1 kPa An isoteniscope (standard) procedure for measuring vapor pressures of liquids from 110¹ to 100 kPa (approximately 1 to 760 torr) is available in Test Method D2879. A DSC (standard) procedure for measuring vapor pressures from 210¹ to 100 kPa (approximately 1 to 760 torr) is available in Test Method E1782. A gas-saturation procedure for measuring vapor pressures from 110¹¹ to 1 kPa (approximately 10¹⁰ to 10 torr) is presented in this test method. All procedures are subjects of U.S. Environmental Protection Agency Test Guidelines.

1.2The gas saturation method is very useful for providing vapor pressure data at normal environmental temperatures (-40 to +60C). At least three temperature values should be studied to allow definition of a vapor pressure-temperature correlation. Values determined should be based on temperature selections such that a measurement is made at 25C (as recommended by IUPAC) (1),2 a value can be interpolated for 25C, or a value can be reliably extrapolated for 25C. Extrapolation to 25C should be avoided if the temperature range tested includes a value at which a phase change occurs. Extrapolation to 25C over a range larger than 10C should also be avoided. If possible, the temperatures investigated should be above and below 25C to avoid extrapolation altogether. The gas saturation method was selected because of its extended range, simplicity, and general applicability (2). Examples of results produced by the gas-saturation procedure during an interlaboratory evaluation are given in Table 1. These data have been taken from Reference (3).

1.3The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4This standard does not purport to address all of the safety problems, 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.