Flammable Liquid Packing Group
This tool determines packing group for materials already known to be Class 3 flammable liquids. It does not determine hazard class.
Packing group =
PG II
Flash point 18 °C · initial boiling point 140 °C
49 CFR 173.121(a)(1) (verified against the primary text) — as of 2026-07-12. eCFR
Reference only. Not legal or regulatory advice. Verify against the primary source before you act.
How it works
For a material already established as a DOT Class 3 flammable liquid, 49 CFR 173.121(a) assigns a packing group from two lab values: closed-cup flash point and initial boiling point (IBP).
- Initial boiling point ≤ 35 °C → Packing Group I
- Flash point < 23 °C (and IBP > 35 °C) → Packing Group II
- Flash point 23 °C–60 °C (and IBP > 35 °C) → Packing Group III
- Flash point > 60 °C → not a Class 3 flammable liquid
This tool does not determine hazard class — it assumes Class 3 is already established and assigns only the packing group. It does not evaluate subsidiary hazards, classification precedence, or the viscous-liquid packing-group relaxation in 173.121(b); those are refused with a pointer to the primary text.
49 CFR 173.121(a)(1) (verified against the primary text) — eCFR · as of 2026-07-12.
Worked example
A solvent has a closed-cup flash point of 18 °C and an initial boiling point of 140 °C.
IBP (140 °C) is above 35 °C, so it is not PG I. Flash point (18 °C) is below 23 °C, so it is Packing Group II.
Sources
Packing group assignment for Class 3 flammable liquids
U.S. Department of Transportation, PHMSA, as of 2026-07-12
49 CFR 173.121(a)(1) (verified against the primary text)
open the source
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Data vintage
- Data: DOT Class 3 packing-group criteria, U.S. Department of Transportation, PHMSA eCFR Title 49, current as of 2026-04-17, retrieved 2026-07-12.Flash-point and boiling-point criteria, not a substance list, so no entry count applies.
last updated 2026-07-12