UN/NA Number Reference
DOT Class 2.2 Non-Flammable Gas placard

UN 2201: Nitrous oxide, refrigerated liquid

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 2201 is assigned the proper shipping name Nitrous oxide, refrigerated liquid in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 2.2 Non-Flammable Gas material. Required label(s): 2.2, 5.1.

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 122)

Hazards: Oxidizer. Vigorously accelerates combustion. May cause fire or explosion on contact with fuels.

Fire: Use water only. Do not use dry chemical or CO2. Cool containers with flooding water.

Spill: Stop leak if safe. Do not touch. Keep combustibles away.

Chemical and Physical Properties

Nitrous oxide is a colorless, sweet-tasting gas. It is also known as "laughing gas". Continued breathing of the vapors may impair the decision making process. It is noncombustible but it will accelerate the burning of combustible material in a fire. It is soluble in water. Its vapors are heavier than air. Exposure of the container to prolonged heat or fire can cause it to rupture violently and rocket. It is used as an anesthetic, in pressure packaging, and to manufacture other chemicals.

CAS Number: 10024-97-2
Molecular Formula: N2O
Molecular Weight: 44.013 g/mol
Color / Form: Colorless gas [Note: Shipped as a liquified compressed gas]
Odor: Slightly sweetish
Boiling Point: -129.1 F
Melting Point: -131.5 °F (USCG, 1999)
Specific Gravity: 1.266 at -128.2 F
Vapor Pressure: 51.3 atm
Vapor Density: 1.53 (heavier than air)
Water Solubility: 0.1 % at 77 F
Log P: 0.36

Regulatory Data

OSHA PEL
none
NIOSH REL
TWA 25 ppm (46 mg/m 3 ) (TWA over the time exposed) [*Note: REL for exposure to waste anesthetic gas.]
IDLH
N

Special Provisions

49 CFR 172.102 special provision codes for this entry: B6, T75, TP5, TP22. 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 2201 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.