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D5471-23 – Standard Test Method Technical Guide
📜 Scope and Applicability of D5471-23
ASTM D5471-23 defines the standard specification for ortho-Xylene 980, a critical aromatic hydrocarbon used extensively in the chemical industry. This specification is under the jurisdiction of ASTM Committee D16 and is specifically tailored to ensure high purity and quality for industrial processing. The standard applies to all properties enumerated for determining conformance.
The standard outlines strict conformance requirements. For determining conformance, an observed or calculated value shall be rounded to the nearest unit in the last right-hand digit used in expressing the specification limit, per Practice E29. All values stated in SI units are regarded as standard. Users must also consult current OSHA regulations and supplier Safety Data Sheets for safe handling of all materials.
🧪 Key Property Specifications and Test Methods
Ortho-Xylene 980 must meet stringent physical and chemical properties to ensure suitability for downstream processes. The table below summarizes the critical specifications and their corresponding ASTM test methods as defined in the standard.
| 📐 Property | 🎯 Specification Limit | ⚡ Test Method(s) |
|---|---|---|
| Purity | 98.0 mass %, min | D7504 |
| Nonaromatic Hydrocarbons | 0.5 mass %, max | D7504 |
| p-Xylene + m-Xylene | 1.3 mass %, max | D7504 |
| C9 and Heavier Aromatics | 0.8 mass %, max | D7504 |
| Cumene | 0.5 mass %, max | D7504 |
| Bromine Index | 100 mg/100 g, max | D1492 or D5776 |
| Color, Pt-Co scale | 10, max | D5386 or D8005 |
| Distillation Range (at 144.4 °C, 101.3 kPa) | 2.0 °C, max | D850 |
| Appearance | Pass (free of haze, particulates) | E2680 |
⚠️ Important Safety Note on Cumene: Per Section 3.1, Cumene is a significant component in o-xylene. The standard explicitly notes it “may contribute to deflagrations in some processes under certain conditions.” Strict adherence to the 0.5 mass % maximum limit is critical for process safety.
⚙️ Testing and Quality Assurance Protocols
The standard mandates specific ASTM methods for verification. Purity and hydrocarbon impurities are determined using D7504 (Gas Chromatography and Effective Carbon Number). The distillation range is strictly controlled via D850, with a maximum allowable range of 2.0 °C at the defined boiling point of 144.4 °C at 101.3 kPa.
For bromine index, either D1492 (Coulometric Titration) or D5776 (Electrometric Titration) is acceptable, giving laboratories flexibility in analytical equipment. Sampling should be conducted according to Practice D3437.
| 🟦 Test Parameter | 📏 Key Details |
|---|---|
| Minimum Purity | 98.0 mass % |
| Max Impurities (p/m-Xylene) | 1.3 mass % |
| Referee Method Protocol | If more than one method is listed, the producer and user must agree on the referee method. |
| Rounding of Data | Per Practice E29 to determine conformance with the specification limit. |
💡 Referee Method Insight: When a property lists multiple test methods (e.g., two methods for Bromine Index or Color), the standard requires the producer and user to mutually agree upon a single referee method to resolve any potential disputes in the final determination.
❓ Frequently Asked Questions
🔍 What grade of o-xylene does D5471-23 cover?
This standard specifically covers the grade identified as Ortho-Xylene 980, requiring a minimum purity of 98.0% by mass. It is an essential feedstock for the production of phthalic anhydride and other chemical intermediates.
💡 What is the significance of the bromine index specification?
The bromine index indicates the level of unsaturates or olefinic impurities in the o-xylene. D5471-23 sets a maximum limit of 100 mg/100 g, ensuring the product meets a high standard for chemical stability and is suitable for sensitive downstream processes where unsaturates may cause fouling or unwanted side reactions.
⚡ How is conformance with the specification determined?
Per Section 1.2 of the standard, conformance is determined by rounding observed or calculated values to the nearest unit in the last right-hand digit of the specification limit. This process follows the rounding-off method of Practice E29.
📌 Which analytical methods are used for impurity profiling?
The standard relies primarily on Test Method D7504 (Gas Chromatography and Effective Carbon Number) for determining purity, nonaromatic hydrocarbons, p/m-xylenes, C9+ aromatics, and cumene content. This method provides a comprehensive impurity profile for the ortho-Xylene 980 grade.