USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

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

Interpretation Response #99-0224 ([HMT Associates, L.L.C.] [Mr. E.A. Altemos])

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

Interpretation Response Details

Response Publish Date:

Company Name: HMT Associates, L.L.C.

Individual Name: Mr. E.A. Altemos

Location State: DC Country: US

View the Interpretation Document

Response text:

January 31, 2000


Mr. E.A. Altemos                           Ref No. 99-0224
HMT Associates, L.L.C.
1850 K Street, N.W.
Suite 200
Washington, DC 20006-3500

Dear Mr. Altemos:

This is in response to Your letter of August 18, 1999, concerning applicability of the Hazardous Materials Regulations (HMR; 49 CFR parts 171-180) to a compressed air system which is
permanently mounted on a commercial motor vehicle and used to discharge a non-hazardous liquid from a bulk tank on the vehicle.

You ask whether such a system is considered to be outside the scope of the HMR, consistent with an opinion issued by this office on July 26, 1994, in the same manner as “fuel systems and equipment such as fire extinguishers, cargo heaters, and air conditioners.  In that opinion, this Office affirmed that equipment that is an integral part of a motor vehicle is not subject to requirements of the HMR.  That opinion, however, does not extend to truck-mounted systems designed to facilitate, by pressurization or otherwise, the unloading of cargoes (hazardous or non­hazardous) during transportation in commerce.

From your description of the pressure unloading system, it appears that the receiving tank may conform to requirements in § 173.6(a)(2) for certain Division 2.2 materials of trade.  This section specifies that the receiving tank must be manufactured to American Society of Mechanical Engineers (ASME) standards and have a rated capacity of not more than 70 gallons water capacity.  In addition, to qualify for the materials of trade exception the vehicle must be operated by a private motor carrier in direct support of a principal business that is other than transportation.  If the provisions of § 173.6 are met, then the system is not subject to any other requirements of the HMR.

I hope this satisfies your request.



Thomas G. Allan
Senior Transportation Regulations Specialist
Office of Hazardous Materials Standards


Regulation Sections

Section Subject
173.6 Materials of trade exceptions