UN/NA Number Reference
DOT Class 2.3 Toxic Gas placard

UN 2191: Sulfuryl fluoride

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 2191 is assigned the proper shipping name Sulfuryl fluoride in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 2.3 Toxic Gas material. Required label(s): 2.3.

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 123)

Hazards: TOXIC. May be fatal if inhaled. Corrosive to metals and tissue. Vapors heavier than air.

Fire: Small: dry chemical or CO2. Large: water spray or fog. Do not use water jet.

Spill: Fully encapsulating suit. Stop leak if safe. Use water spray to reduce vapor.

Chemical and Physical Properties

Sulfuryl fluoride appears as a colorless odorless gas. Shipped as a liquefied gas under its own vapor pressure. Noncombustible. Heavier than air. Very toxic by inhalation. Contact with the unconfined liquid can cause frostbite. Prolonged exposure to heat can cause containers to rupture violently and rocket. Used as an insecticide fumigant in wooden structures to control termites and wood-infesting beetles, and used in organic synthesis.

CAS Number: 2699-79-8
Molecular Formula: F2O2S
Molecular Weight: 102.06 g/mol
Color / Form: Colorless gas [Note: shipped as a liquified compressed gas]
Odor: Odorless
Boiling Point: -68 F
Melting Point: -212 °F (NIOSH, 2024)
Specific Gravity: 3.72 G/L, 1.7 G/L
Vapor Pressure: 15.8 atm at 70 F
Vapor Density: 3.72 (heavier than air)
Water Solubility: 0.2 % at 32 F

Regulatory Data

CERCLA RQ (40 CFR 302.4)
1 lb
OSHA PEL
TWA 5 ppm (20 mg/m 3 )
NIOSH REL
TWA 5 ppm (20 mg/m 3 ) ST 10 ppm (40 mg/m 3 )
IDLH
200 ppm

A release of this material at or above its CERCLA reportable quantity (1 lb) requires immediate notification to the National Response Center at 800-424-8802.

Special Provisions

49 CFR 172.102 special provision codes for this entry: 4. 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 2191 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.