Ask X3What does 49 CFR 173.121 (Class 3—Assignment of packing group) require?
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According to 49 CFR 173.121, the packing group for a Class 3 material is assigned based on column 5 of the § 172.101 Table. If that table provides more than one packing group, you must determine the correct packing group by applying the following criteria based on the closed-cup flash point and initial boiling point:
* Packing Group I: Initial boiling point of 35 °C (95 °F) or less, and any flash point.
* Packing Group II: Initial boiling point greater than 35 °C (95 °F), and a flash point less than 23 °C (73 °F).
* Packing Group III: Initial boiling point greater than 35 °C (95 °F), and a flash point of 23 °C through 60 °C (73 °F through 140 °F).
Additionally, 49 CFR 173.121 outlines specific approved test methods to determine the initial boiling point (such as ASTM D 86, ASTM D 1078, ISO 3405, ISO 3924, ISO 4626, or ASTM D7900), and provides criteria under which certain viscous Class 3 materials normally assigned to Packing Group II may instead be grouped in Packing Group III (based on specific solvent separation, absence of Division 6.1 or Class 8 substances, packaging capacity limits, and viscosity/flash point criteria).