UN/NA Number Reference

UN 1001: Acetylene, dissolved

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1001 is assigned the proper shipping name Acetylene, dissolved in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 2.1 Flammable Gas material. Required label(s): 2.1.

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 116)

Hazards: May polymerize explosively when heated or involved in fire. Extremely flammable. BLEVE risk.

Fire: Fight fire from maximum distance. Do not extinguish unless flow stopped. Cool containers with water.

Spill: Eliminate all ignition sources. Stop leak if safe.

Chemical and Physical Properties

Acetylene appears as a colorless gas with a faint garlic-like odor. Easily ignited and burns with a sooty flame. Gas is lighter than air. Flame may flash back to the source of a leak very easily. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.

CAS Number: 74-86-2

Molecular Formula: C2H2

Molecular Weight: 26.04 g/mol

Color / Form: Colorless gas ... [Note: Shipped under pressure dissolved in acetone]

Odor: Not unpleasant odor unless impure (due to phosphine)

Boiling Point: -119 F

Melting Point: -119 °F (Sublimes) (NIOSH, 2024)

Flash Point: 0 F

Autoignition: 581 °F (USCG, 1999)

Specific Gravity: 0.613 at -112 F

Vapor Pressure: 44.2 atm

Vapor Density: 0.91 (lighter than air)

Water Solubility: 2 %

Log P: log Kow = 0.37

Regulatory Data

OSHA PEL

none

NIOSH REL

C 2500 ppm (2662 mg/m 3 )

IDLH

Special Provisions

49 CFR 172.102 special provision codes for this entry: N86, N88. 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.

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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.