Petroleum Fractions
Definition
Crude-oil distillation cuts ordered by boiling range: light (C4 to C9, pentane, hexane, naphtha), medium (C8 to C12, mineral spirits, kerosene), heavy (C9 to C25, diesel, fuel oil) and lubricating oil residue.
- Light fraction
- C4 to C9, includes pentane, hexane, naphtha
- Medium fraction
- C8 to C12, includes mineral spirits, kerosene
- Heavy fraction
- C9 to C25, includes diesel, fuel oil
- Classification basis
- Boiling range during crude-oil distillation
Common questions
Why does fraction classification matter in fire debris analysis?+
The recovered ignitable liquid's fraction range narrows the list of plausible commercial products, helps distinguish deliberate accelerant use from background pyrolysis products, and guides which reference standards a lab compares the sample against.
Can a single petroleum product contain more than one fraction?+
Yes. Commercial products are often blends, and evaporation or partial combustion at a fire scene can shift the recovered profile toward the heavier components, which analysts account for when interpreting a weathered sample.
Related terms
- ASTM E1387 / E1618
- ASTM standards for ignitable-liquid residue analysis. E1387 was the older colour-coded scheme; E1618 (current) defines the modern eight-class system based on GC-MS...
- Extracted Ion Profile (EIP)
- A GC-MS chromatographic display plotting only ions of a specified m/z value against retention time, effectively filtering out all compounds that do...
- Ignitable Liquid
- In fire debris analysis, any flammable liquid that could serve as an accelerant. E1618 classifies ignitable liquids into eight categories based on...
- Passive Headspace Charcoal-Strip Extraction
- ASTM E1412 method. Fire debris is sealed in an unlined metal can with a suspended activated-charcoal strip, heated to 60 to 80...
- Pyrolysis Products
- Hydrocarbons released when synthetic substrates (polyurethane foam, carpet, vinyl flooring) burn or smoulder. They overlap the petroleum range and are the main...
- SPME
- Solid-phase microextraction. A polymer-coated fused-silica fibre (typically PDMS or PDMS-DVB) is exposed to vial headspace, then thermally desorbed in the GC injector....
- Weathering
- Loss of lighter components from an ignitable liquid by evaporation during and after the fire. Weathered gasoline loses C4 to C7 first;...