ILR
Definition
Ignitable liquid residue. The chemical evidence that an accelerant was used, classified per ASTM E1618 into classes (gasoline, distillates, naphthenic-paraffinic, etc.).
- Expansion
- Ignitable liquid residue
- Governing standard
- ASTM E1618
- Example classes
- Gasoline, distillates, naphthenic-paraffinic products
- Evidence role
- Chemical indicator that an accelerant was used
Common questions
What is the difference between ILR classes like gasoline and naphthenic-paraffinic products?+
The ASTM E1618 classes group ignitable liquids by their chromatographic hydrocarbon pattern rather than by brand name. Gasoline shows a distinct aromatic and branched-alkane profile, while naphthenic-paraffinic products, common in some solvents and lighter fluids, show a different ring and chain structure that GC-MS separates into its own class.
Does detecting ILR at a scene mean the fire was deliberately set?+
Not on its own. As with any ILR finding, the residue must be considered alongside where it was found, whether it matches items legitimately present at the scene, and the overall burn pattern, since accelerant sources can be innocent as well as incendiary.
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