UN/NA Number Reference
DOT Class 3 Flammable Liquid placard

UN 1265: Pentanes

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1265 is assigned the proper shipping name Pentanes in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 3 Flammable Liquid material, Packing Group I. Required label(s): 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 128)

Hazards: HIGHLY FLAMMABLE. Vapors may form explosive mixtures with air. Vapors heavier than air. Runoff may pollute waterways.

Fire: Small: dry chemical, CO2, water spray, regular foam. Large: water spray, fog, regular foam. Do not use straight streams.

Spill: Eliminate ignition sources. Stop leak if safe. Use foam to suppress vapors. Absorb with earth, sand, or other absorbent. Prevent runoff to waterways.

Chemical and Physical Properties

N-pentane appears as a clear colorless liquid with a petroleum-like odor. Flash point 57 °F. Boiling point 97 °F. Less dense than water and insoluble in water. Hence floats on water. Vapors are heavier than air.

CAS Number: 109-66-0
Molecular Formula: C5H12
Molecular Weight: 72.15 g/mol
Color / Form: Colorless liquid [Note: A gas above 97 degrees F. May be utilized as a fuel].
Odor: Pleasant
Boiling Point: 97 F
Melting Point: -202 °F (NTP, 1992)
Flash Point: -57 F
Autoignition: 500 °F (USCG, 1999)
Specific Gravity: 0.626 (floats on water)
Vapor Pressure: 400 mmHg at 65.3 F
Vapor Density: 2.48 (heavier than air)
Water Solubility: less than 1 mg/mL at 70 F
Log P: log Kow = 3.39

Regulatory Data

CERCLA RQ (40 CFR 302.4)
1 lb
OSHA PEL
TWA 1000 ppm (2950 mg/m 3 )
NIOSH REL
TWA 120 ppm (350 mg/m 3 ) C 610 ppm (1800 mg/m 3 ) [15-minute]
IDLH
1500 ppm [10%LEL]

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: T11, TP2. 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 1265 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.