The Thirteen Compatibility Groups of Explosives

Class 1 divisions are further divided into 13 compatibility groups that identify the kinds of explosive articles and substances that are deemed to be compatible. Explosives are deemed compatible if they can be stowed together without significantly increasing either the probability of an accident or the magnitude of the effects if an accident was to occur.

The compatibility groups are designated A through S. You can review 49 CFR §177.848, IMDG Table 2.1.2.3, or IATA Table 3.1.A for the compatibility groups assigned to the divisions of explosives and a description of the article or substance.

Explosives in Compatibility Group S may be stowed with explosives in any other compatibility group. However, Division 1.4S explosives are subject to tests to verify that any hazardous effects are contained within the package. Evidence of a hazardous effect outside the package includes the following:

• Dent or perforation of the witness plate beneath the package
• Flash or flame capable of ignition
• Disruption of the package causing projection of the contents
• A projection that passes completely through the packaging

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