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D2712-23 – Standard Test Method Technical Guide
📐 Scope and Application
This test method, designated D2712-23, covers the determination of hydrocarbon impurities in high purity propylene (propene) with a minimum purity of 97% by mass (concentrates). The method is applicable for impurities in the concentration range of 0.35 mg/kg to 8575 mg/kg, including a comprehensive list of hydrocarbons such as methane, ethane, ethylene, propane, acetylene, isobutane, propadiene, normal butane, trans-2-butene, butene-1, isobutylene, cis-2-butene, isopentane, methylacetylene, normal pentane, and 1,3-butadiene. Optionally, the analysis can be extended to include pentenes/hexanes and heavier components as specified in section 6.3.
Non-hydrocarbon impurities are not determined by this method. Purity is calculated by difference, subtracting the sum of determined analytes from 100%. The standard emphasizes that it is optimized for high-purity propylene and should not be used for lower purity samples due to cross-contamination risks. All measurements are in SI units.
⚠️ Safety Warning: This method involves hazardous materials and operations. Users must obtain LPG safety training, such as the “Liquefied Petroleum Gases Sampling Safety” course on ASTM.org, and follow safe practices.
⚙️ Test Method and Sampling
The test method utilizes gas chromatography (GC) for separation and quantification of hydrocarbon impurities. Proper sampling is critical, following ASTM Practices D1265 (manual sampling), D3700 (floating piston cylinder), or F307 (pressurized gas sampling). The method references several standards including D1835 for LPG specifications and E355 for GC terminology. The analysis requires careful calibration and control to ensure accuracy at trace levels.
For detection and quantification, the GC system must be capable of resolving the specified hydrocarbons. The method details the procedure for sample introduction and data analysis. It is recommended to follow the standard closely for reliable results.
💡 Note: This test method may optionally include pentenes/hexanes and heavier components. Refer to section 6.3 of the standard for additional details.
📊 Key Measured Properties and Reference Data
The following table lists the hydrocarbon impurities that can be determined using this test method, along with their overall concentration range as specified in the standard.
| 🟦 Component | 📏 Concentration Range (mg/kg) |
|---|---|
| Methane | 0.35 – 8575 |
| Ethane | 0.35 – 8575 |
| Ethylene | 0.35 – 8575 |
| Propane | 0.35 – 8575 |
| Acetylene | 0.35 – 8575 |
| Isobutane | 0.35 – 8575 |
| Propadiene | 0.35 – 8575 |
| Normal Butane | 0.35 – 8575 |
| Trans-2-butene | 0.35 – 8575 |
| Butene-1 | 0.35 – 8575 |
| Isobutylene | 0.35 – 8575 |
| Cis-2-butene | 0.35 – 8575 |
| Isopentane | 0.35 – 8575 |
| Methylacetylene | 0.35 – 8575 |
| Normal Pentane | 0.35 – 8575 |
| 1,3-Butadiene | 0.35 – 8575 |
Additionally, the standard references several key ASTM standards for sampling and terminology, which are essential for proper application.
| 🟦 Standard | 📏 Description |
|---|---|
| D1265 | Practice for Sampling LP Gases, Manual Method |
| D1835 | Specification for LP Gases |
| D3700 | Practice for Obtaining LPG Samples Using a Floating Piston Cylinder |
| E355 | Practice for Gas Chromatography Terms and Relationships |
| F307 | Practice for Sampling Pressurized Gas for Gas Analysis |
❓ Frequently Asked Questions
🔍 What is the minimum purity of propylene required for this test method?
The test method is designed for propylene materials with 97% by mass or greater purity (concentrates).
💡 How is purity calculated if non-hydrocarbon impurities are not measured?
Purity is calculated by difference: subtract the total concentration of all determined hydrocarbon impurities from 100%.
⚡ What safety training is recommended for users?
Users should obtain LPG safety training, such as the “Liquefied Petroleum Gases Sampling Safety” eLearning course available on ASTM.org.
📌 Can this test method be used for lower purity propylene samples?
No, it is not recommended due to the potential for cross-contamination between samples when used for trace level impurities.