ASTM D4056 Standard Test Method for Estimation of Solubility of Water in Hydrocarbon and Aliphatic Ester Lubricants
1. Scope
1.1 This test method covers a procedure for estimating the equilibrium solubility of water and its vapor in hydrocarbon and aliphatic ester lubricants, at temperatures between 277 and 373 K. The test method is limited to liquids of low to moderate polarity and hydrogen bonding, with predicted solubilities not over 1000 ppm by weight in hydrocarbons, or 30 000 ppm by weight in oxygenated compounds, at 298 K.
1.2 Specifically excluded are olefins, nitriles, nitro compounds, and alcohols.
1.3 This test method is recommended only for liquids not containing widely different chemical species. This excludes blends of esters with hydrocarbons, and lubricants containing detergents, dispersants, rust preventives, or load carrying additives.
1.4 The values stated in SI units are to be regarded as the standard. Values in parentheses are given for information only.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
D94 Test Method for Saponification Number of Petroleum Products
D1218 Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids
D1298 Practice for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method
D2502 Test Method for Estimation of Molecular Weight (Relative Molecular Mass) of Petroleum Oils from Viscosity Measurements
D3238 Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 charge transfer parameter - the portion of the solubility parameter not attributed to London or Keesom forces.
3.1.1.1 Discussion - It includes hydrogen bonds, induced dipoles, and other quasichemical forces.
3.1.1.2 Discussion - The square of the solubility parameter equals the sum of the squares of the three partial parameters.
3.1.2 dispersion parameter - the portion of the solubility parameter attributed to London forces.
3.1.3 polar parameter - the portion of the solubility parameter attributed to Keesom (permanent dipole) forces.
3.1.4 solubility parameter - the square root of the cohesive energy density (heat of vaporization minus work of vaporization, per unit volume of liquid), at 298 K.
3.2 Symbols:
CA = percentage of aromatic carbons,
CN = percentage of naphthenic carbons,
d = density of lubricant at 298 K, g/mL,
G = solubility by weight, mg/kg (ppm),
M = molecular weight of lubricant, g/mol,
nD = refractive index of lubricant at 298 K,
RH = relative humidity, %
S = saponification number, mg of KOH/g of lubricant,
T = system temperature, K,
V = molar volume of lubricant, mL/mol,
x = mole fraction of water in equilibrium mixture,
y = Lorentz-Lorenz refractivity function,
δd = ispersion parameter, (MPa)(0.5),
P = polar parameter, (MPa)(0.5),
H = charge transfer parameter, (MPa)(0.5),
θ1 = volume fraction of lubricant in equilibrium mixture, and
θ2 = volume fraction of water in equilibrium mixture.
