Packaging of Toxic by Inhalation Liquids
Pipeline and Hazardous Materials Safety Administration · Feb 2, 2006 · Reference No. 05-0318
Interprets: 49 CFR § 173.244
Reggie’s quick take
Someone asked whether a toxic-by-inhalation liquid, corrosive, n.o.s., UN3390, Packing Group I, may be shipped in an insulated DOT 412 cargo tank motor vehicle. PHMSA says yes. Under § 173.244(b), a DOT 412 cargo tank is authorized for this Zone B inhalation hazard material, and Special Provision B14 in § 172.102 requires that the tank be insulated.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This responds to your letter dated December 21, 2005, regarding the packaging of toxic by inhalation liquids under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask whether liquids described as "Toxic by inhalation liquid, corrosive, n.o.s., 6.1, UN3390, PG I, 8" may be transported in an insulated DOT 412 cargo tank motor vehicle.
The answer is yes. The cargo tanks authorized for a Zone B inhalation hazard material (UN3390) are found in § 173.244 of the HMR, as limited by the applicable special provisions of § 172.102. As prescribed in § 173.244(b), a DOT 412 cargo tank is authorized for a Zone B inhalation hazard material (UN3390). In accordance with Special Provision B14, the cargo tank must be insulated.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.