Class 4.2 and Class 4.3 goods react with their surroundings: 4.2 substances can heat up and ignite on contact with air, and 4.3 substances release flammable gas on contact with water. Both need dry, carefully packed, carefully stowed handling. We check acceptance with carriers before booking because many of these products are restricted.
Class 4.2: spontaneously combustible substances
- Pyrophoric substances that ignite in air
- Self-heating substances, which heat up in air without an energy supply and may catch fire
- Typical goods: charcoal, activated carbon, wetted metal catalysts such as palladium on carbon, and some metal powders
Class 4.3: substances which emit flammable gas when wet
- Calcium carbide, which releases acetylene in contact with water
- Alkali metals such as sodium and potassium, and some metal hydrides
- Uncoated aluminium and magnesium powders, and sodium borohydride
Handling and packaging
- Strong UN-certified packaging, sealed and kept dry, sometimes with inert or protective inner packing
- Dry containers with a condensation and leak check before loading
- Segregation from water, liquids, oxidizers and heat sources
- Some goods are forbidden on aircraft or accepted only on cargo aircraft, so most are shipped by sea
Carriers and ports apply their own acceptance rules to these classes, and some 4.2 and 4.3 goods are declined outright. Send us the UN number and SDS early.
What we need to quote your shipment
Send us the details below and we will confirm routing, carrier acceptance and price for your Class 4.2 or 4.3 cargo.
- Product name, UN number, class and packing group (from the SDS, Section 14)
- Current SDS (16 sections) and, for batteries, the UN38.3 test summary
- Quantity, package type and gross weight per package
- Origin city or port, destination port or address, and Incoterm
- Cargo ready date and required delivery date
FAQ
Is activated carbon dangerous goods?
Some grades are. Activated carbon and charcoal can self-heat and are regulated as Class 4.2 depending on the product and test results. Send us the SDS or a self-heating test report.
Are lithium metal batteries Class 4.3?
No. Lithium batteries are shipped as Class 9. See our battery logistics page.
Regulations are revised regularly. IMDG Code Amendment 42-24 is mandatory from 1 January 2026 and the 67th Edition of the IATA Dangerous Goods Regulations applies during 2026. Requirements vary by carrier, port and destination, so please contact us to confirm the rules for your specific shipment.