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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #20-0034

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Railsback Safety Professionals LLC

Individual Name: Rex Railsback

Location State: KS Country: US

View the Interpretation Document

Response text:

May 19, 2020

Rex Railsback
HazMat Specialist
Railsback Safety Professionals LLC
312 Lawrence Avenue
Lawrence, KS  66049

Reference No. 20-0034

Dear Mr. Railsback:

This letter is in response to your April 22, 2020, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the transportation of internal combustion engines and combustible liquids. Specifically, you describe a scenario involving equipment containing an internal combustion engine with a 150-gallon fuel tank. The engine and fuel tank contain diesel fuel with a flashpoint of 125 °F, which has been reclassified as a combustible liquid in accordance with § 173.120(b).

We have paraphrased and answered your questions as follows:

Q1. You ask whether an internal combustion engine containing diesel fuel with a flash point of 125 °F meets the definition of "hazardous material" in § 171.8.

A1. The answer is yes. Internal combustion engines containing a flammable or combustible liquid fuel are classified as a hazardous material (see "UN3528, Engine, internal combustion, flammable liquid powered, 3"). Please note that exceptions from part, or all, of the HMR are offered to UN3528 (see §§ 173.220(h) and 176.906), and to combustible liquids (see § 173.150(f)).

Q2. You ask whether an internal combustion engine's 150-gallon fuel tank, which contains a combustible liquid, meets the definition of a "hazardous material" in § 171.8.

A2. The answer is yes. Fuel tanks that are part of the equipment they power are covered under the description for the engine (UN3528, see above). If the fuel tank is transported separately from the equipment it is intended to power, the fuel inside must be described and transported in accordance with applicable HMR requirements or exceptions (see § 173.150(f)(2) for exceptions provided to bulk packages of combustible liquids).

As defined under § 171.8, "hazardous material" means a substance or material that the Secretary of Transportation has determined is capable of posing an unreasonable risk to health, safety, and property when transported in commerce, and has designated as hazardous under section 5103 of Federal hazardous materials transportation law (49 U.S.C. 5103). The term includes hazardous substances, hazardous wastes, marine pollutants, elevated temperature materials, materials designated as hazardous in the Hazardous Materials Table (see 49 CFR 172.101), and materials that meet the defining criteria for hazard classes and divisions in part 173 of this subchapter.

An internal combustion engine containing flammable or combustible liquid fuel continues to meet the definition of "hazardous material" in § 171.8 even when transported under an exception that provides relief from part, or all of the requirements of the HMR. However, if the engine and fuel tank are purged of fuel in accordance with § 173.220(a), and the engine contains no other hazardous materials, then the engine would no longer be considered a "hazardous material" as defined in § 171.8.

I hope this information is helpful. Please contact us if we can be of further assistance.


Dirk Der Kinderen
Chief, Standards Development Branch
Standards and Rulemaking Division

171.8, 172.101, 173.120(b), 173.220(a), 173.220(h), 176.906, 173.150(f), 173.150(f)(2)

Regulation Sections

Section Subject
171.8 Definitions and abbreviations
172.101 Purpose and use of hazardous materials table
173.120 Class 3-Definitions
173.220 Internal combustion engines, vehicles, machinery containing internal combustion engines, battery-powered equipment or machinery, fuel cell-powered equipment or machinery
176.906 Stowage of engines and machinery