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Interpretation Response #04-0236 ([Tom Dunaway & Associates, Inc] [Mr. Robert Brown, Jr.])

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

Interpretation Response Details

Response Publish Date:

Company Name: Tom Dunaway & Associates, Inc

Individual Name: Mr. Robert Brown, Jr.

Location State: CA Country: US

View the Interpretation Document

Response text:

Nov 16, 2004


Mr. Robert Brown, Jr.                Reference No. 04-0236
Tom Dunaway & Associates, Inc.
P.O. Box 712
Antioch, California 94509

Dear Mr. Brown:

This responds to your letter regarding the proper segregation and separation of a Division 5.1 (oxidizer) and a Class 8 (corrosive) liquid under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, your questions concerns the segregation and separation requirements for hazardous materials identified by the letter “O” in § 177.848(e)(3). You state that you have a client who wishes to transport a Class 8 (corrosive) material and a Division 5.1 (oxidizer) material in a multi-compartmented cargo tank. Your questions are paraphrased and answered as follows:

Q1.      Are these hazardous materials authorized to be transported in adjacent or non-adjacent tanks of the same cargo tank?

Al.        The answer is no. Section 177.848(a)(2) applies to materials that meet one or more hazard class definitions and are in a compartment within a multi-compartmented cargo tank subject to the restrictions in § 173.33. Section 173.33(a)(2) prohibits the loading of materials on the same cargo tank motor vehicle that, if mixed, could result in an explosion, fire, excessive increase in pressure or heat, or the release of toxic vapors. This restriction applies regardless of whether the incompatible materials on the cargo tank motor vehicle are separated by adjacent compartments/tanks or non-adjacent compartments/tanks.

Q2.      If the answer to Q1 is no, would that answer change if the shipper certifies that the
mixture of the contents would not create a fire or a dangerous evolution of heat or gas?

A2.      The answer is yes. Section 173.3 3(a)(2) is not intended to prevent the shipment of materials that, if mixed, would produce a moderate exothermic reaction that would not start a fire, rupture the tank, or release acutely toxic vapors.

Many factors affect how materials may react with each other. They include the chemical composition and properties of the materials involved, and how they react to air, water, contaminants, or temperature conditions during transportation. Because there are so many variables, under the HMR, the parties involved must evaluate the potential risk posed by different materials that are offered and accepted for transportation on the same multi-compartmented cargo tank motor vehicle. If your client has specific questions on making these determination, your client may contact Mr. Charles Hochman, Office of Hazardous Materials Technology, at (202) 366-4545 for assistance.

I hope this satisfies your request.



Hattie L. Mitchell, Chief
Regulatory Review and Reinvention
Office of Hazardous Materials Standards

173.33(a)(2), 177.848(a)(2)

Regulation Sections

Section Subject
173.33 Hazardous materials in cargo tank motor vehicles
177.848 Segregation of hazardous materials