DOT Hazard Class

Class 5.2

Organic Peroxide

49 CFR §173.128

Placard: Red-top / yellow-bottom placard with flame symbol

ERG entries

Divisions

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Packing groups

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Compat groups

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Definition

An organic compound containing oxygen in the bivalent -O-O- structure that may be considered a derivative of hydrogen peroxide, where one or both of the hydrogen atoms have been replaced by organic radicals.

Primary hazards

May explode from heat, shock, friction, or contamination
May ignite spontaneously if contaminated
May burn rapidly with flare-burning effect
May be sensitive to impact or friction
May irritate or burn skin and eyes

Public safety response

Isolate spill or leak area for at least 250 m (800 ft). Do not fight fire when fire reaches cargo — evacuate. Some peroxides require temperature control during transport.

Common materials in this class

Benzoyl peroxide, methyl ethyl ketone peroxide (MEKP), dicumyl peroxide, tert-butyl peroxybenzoate — used as polymerization initiators.

UN3101Organic peroxide type B, liquid UN3103Organic peroxide type C, liquid UN3105Organic peroxide type D, liquid UN3107Organic peroxide type E, liquid UN3109Organic peroxide type F, liquid

Special provisions / notes

Classified into Types A-G by hazard severity. Type A is forbidden from transport. Types B-F are permitted with SADT-based control and emergency temperatures — if the SADT is ≤ 55 °C the peroxide requires refrigeration. Type G is exempt from Class 5.2.