ASTM D2779-92(R2020) pdf free download
ASTM D2779-92(R2020) pdf free download.Standard Test Method for Estimation of Solubility of Gases in Petroleum Liquids
1. Scope
1.1 This test method covers the estimation of the equilib- rium solubility of several common gases encountered in the aerospace industry in hydrocarbon liquids. These include petroleum fractions with densities in the range from 0.63 to 0.90 at 288 K (59°F). The solubilities can be estimated over the temperature range 228 K (−50°F) to 423 K (302°F). 1.2 This test method is based on the Clausius-Clapeyron equation, Henry’s law, and the perfect gas law, with empiri- cally assigned constants for the variation with density and for each gas. 1.3 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only. 1.4 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Terminology
3.1 Definitions: 3.1.1 Bunsen coeffıcient—the solubility of a gas expressed as the volume, reduced to 273 K (32°F) and 101.3 kPa (1 atm), dissolved by 1 volume of liquid at the specified temperature and 101.3 kPa. 3.1.2 Henry’s law—the principle that the ratio of partial pressure to mole fraction of gas in solution is a constant. 3.1.2.1 Discussion—In non-ideal systems the fugacity is used to replace the pressure, but the systems within the scope of this test method can be considered ideal within the limits of the accuracy statement. 3.1.3 Ostwald coeffıcient—the solubility of a gas expressed as the volume of gas dissolved per volume of liquid when the gas and liquid are in equilibrium at the specified partial pressure of gas and at the specified temperature.
4. Summary of Test Method
4.1 Correlations have been established by the National Aeronautics and Space Administration (formerly National Advisory Committee onAeronautics) in NACATechnical Note 3276 (1956) 3 Their work was extended to include most of the data published since that time, and extrapolated by semi- empirical methods into regions where no data are available. 4.2 The only data required are the density ofliquid at 288 K (59°F) and the nature of the gas. These are used in the equations, with the specific constant for the gas from Table 1, or with Fig. 1, to estimate the Ostwald coefficient.
5. Significance and Use
5.1 Knowledge ofgas solubility is ofextreme importance in the lubrication of gas compressors. It is believed to be a substantial factor in boundary lubrication, where the sudden release of dissolved gas may cause cavitation erosion, or even collapse of the fluid film. In hydraulic and seal oils, gas dissolved at high pressure can cause excessive foaming on release ofthe pressure. In aviation oils and fuels, the difference in pressure between take-off and cruise altitude can cause foaming out of the storage vessels and interrupt flow to the pumps.N OTE 1—The constant 0.980 is based on the intermolecular volume of hydrocarbons as measured by compressibility and contraction on freezing. It is also the best empirical fit ofthe data. The use ofthis equation for very dense liquids is inadvisable, as the Ostwald coefficient becomes negative above d = 0.980. The constant 7.70 is also predictable from molecular theory, but the value used was determined empirically.
