UN1929: Potassium dithionite
As listed: Potassium dithionite or Potassium hydrosulfite
UN1929 appears 1 time in the Hazardous Materials Table (49 CFR §172.101). Hazard class 4.2, packing group II.
All §172.101 entries for UN1929
| Proper shipping name | Class | PG | Labels |
|---|---|---|---|
| Potassium dithionite or Potassium hydrosulfite | 4.2 | II | 4.2 |
Open any entry for packaging sections, special provisions, air limits and vessel stowage.
What it means
Packing group ranks danger within the class: PG II = medium danger.
Label codes (column 6): 4.2 → Spontaneously combustible label.
UN numbers are recognized for international and domestic transport.
Example basic description
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
- Match the name. Compare your SDS Section 14 to the proper shipping names above and pick the row with your packing group.
- Read the special provisions on the entry page (§172.102) — they can add limits or exceptions.
- Check packaging — the entry page lists the Part 173 sections for exceptions, non-bulk and bulk.
- Labels & placards. Placarding depends on class and quantity — see Table 1 vs Table 2.
- Emergency response. Find the response guide for UN1929 in the current PHMSA Emergency Response Guidebook.
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Common questions about UN1929
What is UN1929?
UN1929 is the identification number for Potassium dithionite or Potassium hydrosulfite in the DOT Hazardous Materials Table (49 CFR §172.101).
What hazard class is UN1929?
UN1929 is listed under hazard class 4.2 (spontaneously combustible).
What packing group is UN1929?
Packing group for UN1929: II. Where several rows exist, the packing group that fits your material decides which row applies.