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D3827-92 – Standard Test Method Technical Guide
ASTM D3827-92 (Reapproved 2020) specifies a standardized procedure for estimating the equilibrium solubility of common gases in a range of organic liquids. The method is primarily designed for petroleum and synthetic lubricants, fuels, and solvents, operating under the principles of regular solution theory. It relies on the solubility parameter of the solvent and standard conditions to provide reliable estimates across a broad temperature range.
📐 Scope and Applicability
This test method covers the estimation of equilibrium solubility for several common gases in petroleum and synthetic lubricants, fuels, and solvents at temperatures between 0 and 488 K. The values stated in SI units are regarded as the standard.
The method is strictly limited to systems where polarity and hydrogen bonding are not strong enough to cause serious deviations from regularity. Gases such as HCl, NH₃, and SO₂ are specifically excluded, as are hydroxy liquids such as alcohols, glycols, and water. The estimation of CO₂ in nonhydrocarbons is also specifically excluded from this method.
⚠️ Important Exclusions: Do not apply this test method to highly polar gases or solvents. It is specifically not designed for HCl, NH₃, SO₂, or liquids containing hydroxyl groups (e.g., water, alcohols, glycols).
⚙️ Key Terminology and Definitions
The standard establishes specific definitions for solubility coefficients and liquid classifications that are critical for proper application and interpretation of results.
| 🟦 Term | 📏 Symbol / Criterion | 📐 Definition | 🎯 Standard Condition |
|---|---|---|---|
| Bunsen Coefficient | n | Gas volume (reduced to 273 K, 0.10 MPa) dissolved by one volume of liquid. | 273 K, 0.10 MPa |
| Ostwald Coefficient | n | Volume of gas dissolved per volume of liquid at equilibrium. | Specified Temp. & Pressure |
| Solubility Parameter | δ | Square root of the internal energy change of vaporization per unit volume of liquid. | 298 K |
| Distillate Fuel | M < 300 g/mol | Petroleum product with molecular weight below 300 g/mol. | — |
| Halogenated Solvent | Vm < 300 mL/mol | Partially or fully halogenated hydrocarbon. | — |
📊 Accuracy Limitations and Data Sources
The accuracy of the estimation varies significantly depending on the type of liquid solvent. The standard provides explicit guidance on the expected accuracy for different classes of materials.
| 🟦 Liquid Class | 📏 Applicability | 📐 Accuracy Note | ⚡ Limitation |
|---|---|---|---|
| Lubricants | Empirical factors adjusted for this class | Given preference; highest accuracy | — |
| Distillate Fuels | Derived from lubricant estimates | Less accurate than lubricants | — |
| Halogenated Solvents | Treated as simple hydrocarbons | Least accurate | — |
| Highly Aromatic Oils | e.g., Diphenoxy phenylene ethers | N₂ estimate is 43 % higher than observation | Above 363 K |
💡 Accuracy Hierarchy: Lubricants were given preference in this test method. Estimates for distillate fuels are made from the lubricant estimates by a further set of empirical factors, and are less accurate. Estimates for halogenated solvents are made as if they were hydrocarbons, and are the least accurate of the three.
❓ Frequently Asked Questions
🔍 What is the difference between the Bunsen and Ostwald coefficients?
Both coefficients are denoted by n. The Bunsen coefficient normalizes the dissolved gas volume to 273 K and 0.10 MPa. The Ostwald coefficient represents the volume of gas dissolved per volume of liquid at the specified temperature and partial pressure of the measurement itself.
💡 Which gases and liquids are specifically excluded from this test method?
This method excludes gases where polarity and hydrogen bonding cause deviations, specifically HCl, NH₃, and SO₂. Hydroxy liquids such as alcohols, glycols, and water are