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D2163-23 – Standard Test Method Technical Guide
ASTM D2163-23™ is the definitive standard for the quantitative determination of individual hydrocarbons in liquefied petroleum (LP) gases and propane/propene mixtures using gas chromatography. It serves as a critical tool for producers, pipeline operators, and testing laboratories to verify product composition against specifications like D1835. This update (ϵ1) includes an editorial update to the scope in April 2023.
🔍 Scope and Key Referenced Standards
The method covers individual hydrocarbons in the range of C₁ to C₅, with component concentrations determined from 0.01% to 100% by volume. It is specifically applicable to LP gases and propane/propene mixtures but explicitly excludes high-purity propene. The standard advises that hydrocarbons heavier than C₅ and non-hydrocarbon materials are not fully determined by this method, requiring supplementary tests for a complete sample characterization.
A robust test relies heavily on the correct implementation of several referenced standards. Sampling, for instance, must be conducted according to Practice D1265 (manual method) or Practice D3700 (floating piston cylinder), ensuring a representative vapor- or liquid-phase sample is obtained.
| 🆔 Standard | 📝 Purpose in D2163 |
|---|---|
| D1265 / D3700 | Specify the sampling procedure for LPG |
| E355 / E594 | Govern GC terminology and Flame Ionization Detector (FID) testing |
| D2421 | Provides guidelines for interconverting analysis results to gas‑volume, liquid‑volume, or mass basis |
| D2598 | Allows calculation of physical properties (e.g., vapor pressure, density) from the compositional analysis |
⚠️ Safety Advisory: Section 1.4.1 explicitly states that the user should obtain LPG safety training for the safe operation of this test method procedure and related activities. Always consult your organization’s safety data sheets and environmental practices before handling pressurized hydrocarbon samples.
⚙️ Apparatus and Procedure
The central apparatus is a gas chromatograph (GC) equipped with a Flame Ionization Detector (FID), tested in accordance with Practice E594. High-resolution capillary columns are often employed to resolve the complex mixture of saturated and unsaturated hydrocarbons. Practice E1510 provides the standard guidelines for installing these columns. The procedure involves controlled injection of the sample (liquid or vapor phase) into the GC, where components are separated based on their boiling points and interactions with the column stationary phase.
The method requires careful calibration using known reference standards (e.g., GPA Std 2145-03 for hexane reference) to establish retention times and response factors for the identified components.
| 🔬 Parameter | 📏 Specification / Limit |
|---|---|
| Compound Range | C₁ (Methane) to C₅ (Pentanes) |
| Concentration Range | 0.01 % to 100 % by volume |
| Excluded Matrices | High-purity Propene (requires specific methods) |
| Detector Type | Flame Ionization Detector (FID) |
📊 Data Handling and Calculations
Once the chromatogram is generated, peaks are identified by comparing retention times with those of known calibration standards. The concentrations are calculated using area normalization or internal standardization. The raw data can then be interconverted using Practice D2421 to present results on a gas‑volume, liquid‑volume, or mass basis as required by the specific product specification. The final compositional analysis serves as the foundation for calculating other critical physical properties per Practice D2598.
💡 Analysis Tip: While D2163 covers a broad range, confirm your instrument setup is validated for the specific alkane/alkene pairs in your sample. Reliable identification of trace components (down to 0.01 %) requires a high-resolution column and stable temperature programming.
❓ Frequently Asked Questions
🔍 What is the core scope of ASTM D2163-23?
It covers the determination of C₁ to C₅ hydrocarbons in LP Gases and Propane/Propene mixtures at concentrations from 0.01 % to 100 % by volume. It does not specifically address high-purity propene.
💡 What are the required sampling practices?
The standard mandates that samples be taken according to either Practice D1265 (Manual Method) or Practice D3700 (Floating Piston Cylinder) to ensure sample integrity and representativeness.
⚡ Can this method characterize the entire LPG sample?
No. Section 1.2 explicitly states this method does not fully determine hydrocarbons heavier than C₅ or non-hydrocarbon materials. Additional tests are necessary for complete characterization (e.g., for sulfur, water, or complex heavier residues).
📌 How are the results reported in different units?
Following the compositional analysis, Practice D2421 provides the methodology to interconvert the raw gas‑volume percent data into liquid‑volume percent or mass percent, aligning with commercial trading or specification requirements.