ASTM E1782-14 Determination of Vapour Pressure by Thermal Analysis

Scope:

ASTM E1782-14 standard test method evaluates the vapour pressure of liquids using Differential Thermal Analysis (DTA) or Differential Scanning Calorimetry (DSC) techniques at different system pressures. This test method can be applied over a temperature range of 273 to 773 K and for 5 kPa to 2 MPa pressures.

Test Procedure:

In ASTM E1782-14 a specimen in an appropriate container is heated at a constant rate within a DTA or DSC instrument operated under an applied constant vacuum/pressure between 5 kPa and 2 MPa until a boiling endotherm is recorded. Boiling is observed at the temperature where the specimen partial pressure equals the pressure applied to the test chamber. The pressure is recorded during observance of the boiling endotherm and the boiling temperature is recorded as the extrapolated onset temperature.

This measurement is repeated using new specimens for each of five or more different pressures covering the pressure range of interest.

Specimen size:

Typical specimen sizes used for individual pressure measurements are 1 to 5 mg of solid or 1 to 5 μL of liquid.

Data: 

where,

A, B, C—Antoine constants

P = vapor pressure, kPa, and

T = temperature, K.

Conclusion:

ASTM E1782-14 provides detailed procedure to determine vapour pressure of solids or liquids by using thermal analysis.