IATA Class 4 Division 4.1 Classification

Powdered, granular, and pasty solid substances are classified in Division 4.1 when the time of burning of one or more test runs is less than 45 seconds, or when the rate of burning is more than 2.2 mm per second. The testing criteria are described in the UN Manual of Tests and Criteria, Part III, Subsection 33.2.1.

Metal and metal alloy powders are classified in Division 4.1 when they can be ignited and the reaction spreads over the entire length of the sample in 10 minutes or less.

Solids that can cause a fire through friction are also classified in Division 4.1.

Flammable solids, other than metal powders, are assigned to packing groups based on the following criteria:

• If the burning time is less than 45 seconds and the flame passes the wetted zone, then it is assigned to Packing Group II.
• If the burning time is less than 45 seconds and the wetted zone stops the flame propagation for at least 4 minutes, then it is assigned to Packing Group III.

The packing group assignment criteria for metal powders or metal alloys are as follows:

• If the reaction spreads over the whole length of the sample in 5 minutes or less, then it is assigned to Packing Group II.
• If the reaction spreads over the whole length of the sample in more than 5 minutes but less than 10 minutes, then it is assigned to Packing Group III.

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