Hazard Class 5 consists of two divisions:
- Division 5.1, Oxidizing Substances. A material that may, generally by yielding oxygen, cause or enhance the combustion of other materials.
- Division 5.2, Organic Peroxides. Any organic compound that contains oxygen in the bivalent structure and that may be considered a derivative of hydrogen peroxide, where one or more of the hydrogen atoms have been replaced by organic radicals.
Examples of Class 5 materials (not all of which are mailable) include ferric nitrate, hydrogen peroxide, lead perchlorate, lithium nitrate, organic peroxide solids or liquids, and some swimming–pool chemicals.
The following conditions apply:
- International Mail. All oxidizing substances and organic peroxides are prohibited.
- Domestic Mail via Air or Surface Transportation. An oxidizing substance or an organic peroxide that can qualify as mailable limited quantity material or ORM-D material (for surface only) is permitted.
When nonmailable Class 5 materials are found in the mailstream, the procedures in POM 139.117 must be followed if the materials present an immediate threat to persons or property. The procedures in POM 139.118 are followed when there is no immediate threat to persons or property.
The following Class 5 materials are nonmailable:
- Division 5.1, Oxidizing Substances.
- Chlorine dioxide hydrate, frozen.
- Hydrogen peroxide solution (more than 20 percent).
- Perchloric acid.
- Potassium peroxide.
- Sodium chlorite.
- Zinc ammonium nitrate.
- Division 5.2, Organic Peroxides. Organic peroxides are nonmailable unless they can qualify as mailable limited quantity materials or ORM-D materials (for surface only).
The following Class 5 materials are mailable:
- Mailable limited quantity or ORM-D Material. A division 5.1 or 5.2 material that can be reclassified as mailable limited quantity material or ORM-D material (for surface only) is mailable within the requirements in 345.2b.
- Hydrogen Peroxide. There are no restrictions on Division 5.1 hydrogen peroxide solutions up to 8 percent. Solutions of hydrogen peroxide exceeding 8 percent and up to 20 percent are permitted if they can qualify as mailable limited quantity material or ORM-D material (for surface only).
Parcels containing mailable oxidizing substances or organic peroxides must be marked as follows:
- All mailable Division 5.1 and 5.2 materials must be prepared following the conditions for Packaging Instruction 5A in Appendix C.
- For air transportation, parcels containing mailable Division 5.1 or 5.2 materials must bear the DOT square-on-point marking. The top and bottom portions of the square-on-point and the border forming the square-on-point must be black, and the center must be white or of a suitable contrasting background. The symbol “Y” must be black, located in the center of the square-on-point, and clearly visible. Mailpieces must also be marked with the proper shipping name and identification number. Each mailpiece must also bear an approved DOT Class 5.1 or 5.2 hazardous material warning label (see Exhibit 325.2b). A properly completed shipper’s declaration for dangerous goods prepared in triplicate must be affixed to the outside of the mailpiece.
- For surface transportation, parcels containing mailable Division 5.1 or 5.2 materials must be plainly and durably marked on the address side with “Surface Only” or “Surface Mail Only” and “ORM-D,” immediately following or below the proper shipping name (e.g., mailable limited quantity). Optionally, mailpieces may be marked with an approved DOT limited quantity square-on-point marking (see Exhibit 325.2a). The top and bottom portions of the square-on-point and the border forming the square-on-point must be black, and the center must be white or of a suitable contrasting background. Surface shipments containing qualifying ORM-D material bearing the square-on-point limited quantity marking are not required to be marked with the shipping name and identification number. A shipper’s declaration for dangerous goods is not required for mailable Division 5.1 or 5.2 materials sent via surface transportation.
- When DOT square-on-point markings are used, markings must be durable, legible, and readily visible, and must be applied on at least one side or one end of the outer packaging. The border forming the square-on-point must be at least 2 mm in width, and the minimum dimension of each side must be 100 mm, unless the package size requires a reduced size marking of no less than 50 mm on each side.