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D5983-21 – Standard Test Method Technical Guide
ASTM D5983-21 is the standard specification for Methyl Tertiary-Butyl Ether (MTBE) intended for blending with gasolines in automotive spark-ignition engines. Designated under D5983 with the year 2021 edition, this standard outlines requirements for fuel grade MTBE to ensure consistency and performance in fuel blends. It was developed in accordance with internationally recognized principles on standardization established by the World Trade Organization Technical Barriers to Trade Committee.
📐 Scope and Application
This specification covers MTBE utilized in blending with gasolines at 1 % to 15 % by volume, which corresponds to an oxygen content of up to 2.7 % by weight. The fuel must comply with Specification D4814 for automotive spark-ignition engine fuel. Values are stated in SI units, and other MTBE grades may be available for blending that are not covered by this specification.
Other grades of MTBE may be available for blending but are not covered by this specification. Users must ensure the grade meets the requirements for their specific application and verify compliance with regulatory standards.
⚙️ Test Methods and Procedures
The standard references a comprehensive set of ASTM test methods for evaluating critical properties of MTBE. These methods cover physical and chemical characteristics essential for quality control and include techniques for sampling, handling, and analysis.
| 🔬 Property | 📏 Test Method | 🎯 Purpose |
|---|---|---|
| Color | ASTM D156 | Saybolt color by chromometer |
| Gum Content | ASTM D381 | Existing gum in fuels by jet evaporation |
| Sulfur | ASTM D2622 or D4045 | Wavelength dispersive X-ray fluorescence or hydrogenolysis rateometric colorimetry |
| Water Content | ASTM E203 or E1064 | Volumetric or coulometric Karl Fischer titration |
| Silicon | ASTM D7757 | Monochromatic wavelength dispersive X-ray fluorescence |
| MTBE Purity | ASTM D5441 | Gas chromatography analysis for methyl tert-butyl ether |
Additional practices such as D4057 for manual sampling, D4177 for automatic sampling, D4306 for sample containers, and D5854 for mixing and handling liquid samples are critical for representative results. Use Practice E29 for significant digits in test data.
For accurate water content determination, use the appropriate Karl Fischer titration method (E203 or E1064) based on the sample matrix. Ensure sample containers are free of trace contamination per Practice D4306.
📊 Key Definitions and Chemical Properties
The standard defines essential terminology. MTBE is chemically known as 2-methoxy-2-methylpropane with the formula CH₃OC(CH₃)₃. Related oxygenates include methanol (CH₃OH) for context. Oxygenates are molecules composed solely of carbon, hydrogen, and oxygen.
| 📌 Term | 🧪 Definition |
|---|---|
| Methyl Tertiary-Butyl Ether (MTBE) | Chemical compound CH₃OC(CH₃)₃, used as oxygenate in gasoline blends |
| Methanol | Methyl alcohol, the chemical compound CH₃OH |
| Oxygenate | A molecule composed solely of carbon, hydrogen, and oxygen |
Refer to Terminology D4175 for general petroleum product terms. This specification is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants.
❓ Frequently Asked Questions
🔍 What is the primary scope of D5983-21?
To specify fuel grade MTBE for blending with gasolines at 1% to 15% by volume for use as automotive spark-ignition engine fuel, as covered by Specification D4814.
💡 What oxygen content does the MTBE blend provide?
At the maximum blending ratio of 15% by volume, MTBE contributes up to 2.7% by weight oxygen in the final fuel mixture.
⚡ Which test method is used for MTBE purity analysis?
ASTM D5441 is the standard test method for analysis of MTBE by gas chromatography, ensuring accurate purity measurement.
📌 What sampling practices are referenced?
Practices D4057 for manual sampling and D4177 for automatic sampling are referenced to ensure representative sample collection.