Division 4.3 — Dangerous when wet
Substances that emit flammable gases on contact with water.
Carrier acceptance
The published default for this class. A UN-specific rule can override it — lithium batteries and dry ice are both Class 9 and are treated quite differently.
| Carrier | Ground | Air | Position |
|---|---|---|---|
| UPS | contract required | prohibited | Dangerous-when-wet material is not accepted by air. |
| FedEx | contract required | prohibited | Not accepted by air. |
| USPS | prohibited | prohibited | Dangerous-when-wet material is non-mailable. |
| Amazon FBA | prohibited | prohibited | Dangerous-when-wet material is not accepted. |
Carrier positions encode each carrier's published default as of the ruleset date. Tariffs change more often than regulations, and a contracted shipper may hold different terms — confirm against the carrier's current guide before the first shipment of a new item.
Encoded entries (0)
No entries in this class are encoded yet. The table covers the substances that appear in commercial parcel and e-commerce shipping; a classification request that lands here returns needs_review rather than a guess.
Classify a specific product in this class
The class alone does not give you a shipping paper. Send the actual product to POST /api/classify and you get the UN number, the proper shipping name, the packing group and every carrier position for that specific item.
Questions
- What is Division 4.3 — Dangerous when wet?
- Substances that emit flammable gases on contact with water.
- Does Division 4.3 — Dangerous when wet have a packing group?
- No. Entries in this class carry no packing group; the class or division alone determines the packaging and labelling requirements. Assigning a packing group here is a common error on shipping papers.
- Can I ship Division 4.3 — Dangerous when wet by air?
- UPS: prohibited; FedEx: prohibited; USPS: prohibited; Amazon FBA: prohibited. These are published carrier defaults, not regulatory limits — a contracted shipper may hold different terms, and the regulation may permit what the carrier declines.