UN/NA Number Reference
DOT Class 2.3 Toxic Gas placard

UN 2199: Phosphine

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 2199 is assigned the proper shipping name Phosphine 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, 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 119)

Hazards: TOXIC. May be fatal if inhaled or absorbed through skin. Flammable. Vapors heavier than air.

Fire: Small: dry chemical or CO2. Large: water spray or fog. Fight from maximum distance.

Spill: Do not touch. Stop leak if safe. Use water spray to reduce vapor.

Chemical and Physical Properties

Phosphine appears as a colorless gas with a disagreeable odor of fish or garlic. Boiling point -126 °F; freezing point -209 °F. Very toxic by inhalation at extremely low concentrations. Prolonged heating may cause containers to rupture violently and rocket. Rate of onset: Immediate & Delayed (Lungs) Persistence: Minutes - hours Odor threshold: 0.9 ppm Source/use/other hazard: Insecticide; used in manufacture of flame retardants and incendiaries.

CAS Number: 7803-51-2
Molecular Formula: H3P
Molecular Weight: 33.998 g/mol
Color / Form: Colorless gas; flammable
Odor: Disagreeable, garlic-like odor.
Boiling Point: -126 F
Melting Point: -207 °F (EPA, 1998)
Flash Point: Flammable gas
Autoignition: 212 °F (100 °C)
Specific Gravity: 0.746 at -130 F
Vapor Pressure: 760 mmHg at -125.5 F
Vapor Density: 1.17 (heavier than air)
Water Solubility: Slight
pH: SOLN ARE NEUTRAL

Regulatory Data

CERCLA RQ (40 CFR 302.4)
100 lb
EPCRA TPQ (40 CFR 355)
500 lb
OSHA PEL
0.3 0.4 0.3 ppm (ST) 1 ppm
NIOSH REL
TWA 0.3 ppm (0.4 mg/m 3 ) ST 1 ppm (1 mg/m 3 )
IDLH
50 ppm
RCRA Waste Code(s)
[object Object], [object Object]

A release of this material at or above its CERCLA reportable quantity (100 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: 1. 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 2199 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.