UN/NA Number Reference
DOT Class 4.2 Spontaneously Combustible placard

UN 1384: Sodium dithionite

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1384 is assigned the proper shipping name Sodium dithionite in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 4.2 Spontaneously Combustible material, Packing Group II. Required label(s): 4.2.

Packing group indicates the degree of danger within a hazard class: PG I is high danger, PG II medium, PG III low. The proper shipping name, hazard class, UN number, and packing group together form the basic shipping description that must appear on shipping papers and, where required, on the package and placard.

Emergency Response (ERG Guide 135)

Hazards: Spontaneously combustible. May reignite after fire is extinguished. May burn rapidly.

Fire: Small: dry chemical, sand, earth. Large: flooding water. Do NOT use foam.

Spill: Do not touch. Cover with dry earth/sand. Do not get water on spilled substance.

Chemical and Physical Properties

Sodium dithionite is a whitish to light yellow crystalline solid having a sulfur dioxide-like odor. It spontaneously heats on contact with air and moisture. This heat may be sufficient to ignite surrounding combustible materials. Under prolonged exposure to fire or intense heat containers of this material may violently rupture. It is used in dyeing and to bleach paper pulp.

CAS Number: 7775-14-6
Molecular Formula: Na2O4S2
Molecular Weight: 174.11 g/mol
Color / Form: White or grayish-white crystalline powder
Odor: Faint sulfurous
Melting Point: 52 °C (decomposes)
Flash Point: about 100 C (open cup)
Autoignition: about 190 °C
Specific Gravity: 2.38 g/cu cm
Water Solubility: Slightly sol in alcohol
Log P: log Kow = < -4.7

Special Provisions

49 CFR 172.102 special provision codes for this entry: A19, A20, IB6, IP2, T3, TP33, W31. These codes modify the general requirements (packaging, quantity limits, exceptions) for this specific material. Look up each code in 49 CFR 172.102 for the full text.

Need the full interactive record? Open UN 1384 in the SpillNerd lookup tool for the live database entry with placard graphics, GHS pictograms, full segregation tables, and synonym search. For another material, use the UN number and chemical lookup.

Reference data compiled from the DOT Hazardous Materials Table (49 CFR 172.101), the 2024 Emergency Response Guidebook, and public chemical databases (PubChem, NIOSH, EPA). Always verify the correct shipping description against the current regulation and the manufacturer's SDS Section 14 before shipping.