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UN identification number

UN3208: Metallic substance, water-reactive, n.o.s

UN3208 appears 3 times in the Hazardous Materials Table (49 CFR §172.101). Hazard class 4.3, packing group I, II, III.

ID numberUN3208
Hazard class4.3
Packing groupI, II, III
Label codes4.3

All §172.101 entries for UN3208

Open any entry for packaging sections, special provisions, air limits and vessel stowage.

What it means

4.3
Class 4.3 — Dangerous when wet. Materials that give off flammable or toxic gas when they contact water.

Packing group ranks danger within the class: PG I = great danger; PG II = medium danger; PG III = minor danger.

Label codes (column 6): 4.3 → Dangerous when wet label.

UN numbers are recognized for international and domestic transport.

Example basic description

UN3208, Metallic substance, water-reactive, n.o.s, 4.3, PG I

Proper shipping name shown without the table's italic descriptive text. Order per §172.202: ID number, proper shipping name, hazard class, packing group. Example only — add technical names, “RQ”, quantities and other elements your shipment requires.

What to check next

  1. Match the name. Compare your SDS Section 14 to the proper shipping names above and pick the row with your packing group.
  2. Read the special provisions on the entry page (§172.102) — they can add limits or exceptions.
  3. Check packaging — the entry page lists the Part 173 sections for exceptions, non-bulk and bulk.
  4. Labels & placards. Placarding depends on class and quantity — see Table 1 vs Table 2.
  5. Emergency response. Find the response guide for UN3208 in the current PHMSA Emergency Response Guidebook.
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Common questions about UN3208

What is UN3208?

UN3208 is the identification number for Metallic substance, water-reactive, n.o.s in the DOT Hazardous Materials Table (49 CFR §172.101).

What hazard class is UN3208?

UN3208 is listed under hazard class 4.3 (dangerous when wet).

What packing group is UN3208?

Packing group for UN3208: I, II, III. Where several rows exist, the packing group that fits your material decides which row applies.

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Source: Hazardous Materials Table (49 CFR §172.101), eCFR.gov — current as of Oct 23, 2026. View the official table. Reference only — verify current requirements before shipping.