Overview
ISO 3837:1993 - "Liquid petroleum products - Determination of hydrocarbon types - Fluorescent indicator adsorption method" specifies a laboratory procedure to determine the volume percent of saturates, olefins and aromatics in liquid petroleum fractions that distill below 315 °C. The method uses a fluorescent indicator-dyed silica gel adsorption column, ultraviolet (UV) illumination and zone-length measurement to quantify hydrocarbon types. It is intended for full boiling-range samples within defined concentration ranges and includes important warnings about safety and method limitations.
Key topics and requirements
- Scope & concentration ranges: Applicable to aromatics from 5 % to 99 % (V/V), olefins 0.3 % to 55 % (V/V) and saturates 1 % to 95 % (V/V) in petroleum fractions distilling below 315 °C. Precision is not established outside these ranges.
- Principle: ~0.75 ml sample is adsorbed on a fluorescent-dyed silica gel column; an alcohol desorbent (e.g., propan-2-ol) and pressurizing gas elute zones. Under UV (≈365 nm) light the dyed gel shows distinct fluorescent bands for aromatics and olefins; saturates are non-fluorescent. Percent composition is calculated from zone lengths.
- Apparatus & reagents: Glass adsorption columns (precision bore or standard wall), fluorescent indicator-dyed silica gel, silica gel meeting surface-area/pH specs, propan-2-ol, UV light source, gas manifold and vibrator for packing. Accurate packing and column transit time (~1 h target) are required.
- Procedure notes & limitations:
- Samples with dark-coloured components or certain C3–C4 light hydrocarbons may give erroneous results and may require depentanization.
- Oxygenated blending components (e.g., methanol, ethanol, MTBE) typically elute with saturates and are not detected separately; results can be reported oxygenate-free or corrected if oxygenate content is known.
- Method involves hazardous materials and UV exposure-appropriate safety measures required.
- Calculation: Hydrocarbon percentages are calculated from measured zone lengths (aromatics, olefins, saturates) expressed as % (V/V).
Applications and users
- Used for quality characterization of gasoline blending stocks, feeds for catalytic reforming, and products from thermal/catalytic cracking.
- Valuable for refineries, fuel testing laboratories, petrochemical quality control, aviation fuel quality assessment, and research groups monitoring hydrocarbon type distribution.
- Helps inform blending decisions, process control and compliance testing where hydrocarbon type composition is important.
Related standards
- ISO 3171 (sampling), ISO 756-1 (propan-2-ol specification)
- ASTM references cited for silica gel surface area and related procedures (e.g., ASTM D3663, ASTM D4815)
Keywords: ISO 3837:1993, fluorescent indicator adsorption, hydrocarbon types, liquid petroleum products, aromatics, olefins, saturates, silica gel, UV fluorescence, gasoline blending, catalytic reforming.
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