UN/NA Number Reference
DOT Class 3 Flammable Liquid placard

UN 1250: Methyltrichlorosilane

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1250 is assigned the proper shipping name Methyltrichlorosilane in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 3 Flammable Liquid material, Packing Group II. Required label(s): 3, 8.

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 155)

Hazards: TOXIC. Corrosive. Flammable or water-reactive. Produces toxic gases on water contact.

Fire: DO NOT use water unless no alternative. Dry chemical, CO2.

Spill: Do not touch. Keep dry. Use water spray with caution.

Chemical and Physical Properties

Methyltrichlorosilane appears as a colorless fuming liquid with a pungent odor. Flash point 8 °F. Vapor and liquid may cause burns. Denser than water. Vapors are heavier than air.

CAS Number: 75-79-6
Molecular Formula: CH3Cl3Si
Molecular Weight: 149.47 g/mol
Color / Form: COLORLESS LIQUID
Odor: ACRID ODOR, SHARP LIKE HYDROCHLORIC ACID
Boiling Point: 152 F
Melting Point: -108 °F (EPA, 1998)
Flash Point: 15 F
Autoignition: greater than 760 °F (USCG, 1999)
Specific Gravity: 1.27 (sinks in water)
Vapor Pressure: 167.0 [mmHg]
Vapor Density: 5.17 (heavier than air)
Water Solubility: Decomposes in ethanol

Regulatory Data

EPCRA TPQ (40 CFR 355)
500 lb

Special Provisions

49 CFR 172.102 special provision codes for this entry: A7, B6, B77, N34, T10, TP2, TP7, TP13. 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 1250 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.