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D5291-21 – Standard Test Method Technical Guide
🔬 Scope and Applicability
These test methods cover the instrumental determination of carbon, hydrogen, and nitrogen in petroleum products and lubricants. Values obtained represent total carbon, total hydrogen, and total nitrogen. The methods are applicable to samples such as crude oils, fuel oils, additives, and residues for carbon, hydrogen, and nitrogen analysis. The concentration ranges tested are at least 75 % to 87 % by mass for carbon, at least 9 % to 16 % by mass for hydrogen, and <0.1 % to 2 % by mass for nitrogen. However, the nitrogen test method is not applicable to light materials or those containing less than 0.75 % by mass nitrogen, such as gasoline, jet fuel, naphtha, diesel fuel, or chemical solvents. Using Test Method D, levels of 0.1 % by mass nitrogen in lubricants could be determined. These test methods are not recommended for volatile materials like gasoline, gasoline-oxygenate blends, or gasoline type aviation turbine fuels. Results are expressed as mass % of carbon, hydrogen, or nitrogen.
⚠️ These test methods are not recommended for the analysis of volatile materials such as gasoline, gasoline-oxygenate blends, or gasoline type aviation turbine fuels due to potential inaccuracies.
⚙️ Summary of Test Methods
In these test methods, carbon, hydrogen, and nitrogen are determined concurrently in a single instrumental procedure. With some systems, the procedure consists of simply weighing a portion of the sample, placing it in the instrument, and initiating the automatic analytical process. In other systems, the analytical process is manually controlled to some degree. The actual process can vary substantially from instrument to instrument, but all satisfactory processes provide for the conversion of the subject materials to carbon dioxide, water vapor, and elemental nitrogen, respectively, and the subsequent quantitative determination of these gases in an appropriate gas stream.
| 🔍 Element | 📏 Concentration Range (% by mass) |
|---|---|
| Carbon | 75 % to 87 % |
| Hydrogen | 9 % to 16 % |
| Nitrogen | <0.1 % to 2 % |
📊 Key Measured Properties
The results of these tests are expressed as mass percent of carbon, hydrogen, or nitrogen. The values stated in SI units are regarded as standard. The standard also references other ASTM practices for sampling and quality assurance, such as Practices D4057, D4177, and D6299. These test methods were developed in accordance with internationally recognized principles on standardization.
| 🟦 Sample Type | 🎯 Applicability |
|---|---|
| Crude oils, fuel oils, additives, residues | Suitable for carbon, hydrogen, and nitrogen analysis |
| Light materials (gasoline, jet fuel, etc.) | Not applicable for nitrogen analysis |
| Volatile materials | Not recommended for analysis |
💡 For accurate results, ensure proper sample handling and follow the safety guidelines specified in the standard. The user is responsible for establishing safety, health, and environmental practices.
❓ Frequently Asked Questions
🔍 What is the scope of D5291-21?
The standard covers the instrumental determination of carbon, hydrogen, and nitrogen in petroleum products and lubricants, applicable to samples like crude oils, fuel oils, additives, and residues.
💡 What are the concentration ranges for carbon, hydrogen, and nitrogen?
Carbon: 75 % to 87 % by mass; Hydrogen: 9 % to 16 % by mass; Nitrogen: <0.1 % to 2 % by mass.
⚡ Can volatile materials be analyzed using this standard?
No, these test methods are not recommended for volatile materials such as gasoline, gasoline-oxygenate blends, or gasoline type aviation turbine fuels.
📌 What is the basis of the test methods?
The methods involve converting the sample to carbon dioxide, water vapor, and elemental nitrogen, and then quantitatively determining these gases in a gas stream.