Class 4 - Division 4.1, Self-Reactive Substances

A self-reactive substance is thermally unstable and is liable to undergo a strongly exothermic decomposition even without the presence of oxygen.

The decomposition of self-reactive substances is initiated by heat, friction, impact, or contact with catalytic impurities, such as acids and bases. The rate of decomposition is dependent on temperature and the type of substance. Because of this, self-reactive substances must be protected from direct sunlight and all sources of heat. They must also be placed in well-ventilated areas.

Self-reactive substances are classified according to the degree of danger they present.

Self-reactive substances include the following:

• Type B - Self-reactive substance that possesses explosive properties that, when packaged, neither detonates nor deflagrates rapidly, but is liable to undergo a thermal explosion
• Type C - Self-reactive substance that possesses explosive properties that, when packaged, cannot detonate or deflagrate rapidly or undergo a thermal explosion
• Type D - Self-reactive substance that detonates partially but does not deflagrate rapidly and shows no violent effects under heated confinement; does not detonate at all, deflagrates slowly, and shows no violent effects under heated confinement; or does not detonate or deflagrate and shows medium effects when under heated confinement
• Type E - Self-reactive substance that neither detonates nor deflagrates at all and shows low or no effect when heated under confinement
• Type F - Self-reactive substance that neither detonates nor deflagrates at all, shows low or no effect when heated under confinement, and has no explosive power

The following substances are NOT considered self-reactive substances in Division 4.1:

• Explosives that meet the criteria for Class 1
• Oxidizing substances that meet the criteria for Division 5.1, except for mixtures that contain 5% or more of combustible organic substances
• Organic peroxides that meet the criteria for Division 5.2
• Substances with a heat decomposition of less than 300 J/g
• Substances with a self-accelerating decomposition temperature greater than 75°C (167°F) for a 50 kg package

Self-reactive substances may be desensitized through the use of a diluent. If a diluent is used, the self-reactive substance must be tested with the diluents present.

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