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 #06-0160 ([Supervac 2000] [Ms. Nathalie Doyon ])

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

Interpretation Response Details

Response Publish Date:

Company Name: Supervac 2000

Individual Name: Ms. Nathalie Doyon 

Country: CA

View the Interpretation Document

Response text:

Oct 5, 2006

Ms. Nathalie Doyon                 Reference No. 06-0160

Supervac 2000

1043 Rue Renault

St-Jean-Chrysostome, Qc G6Z1B6

Dear Ms. Doyon:

This responds to your fax dated July 14, 2006 requesting clarification on tank outlets for cargo tank motor vehicles in §178.345-11(b)(2) of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask if a double acting valve driven by a self-closing air valve at the top of the tank meets the provisions of § 178.345-11(b)(2).

According to your fax, and as a follow up question to your first response from us on this subject dated July 11, 2006 under Ref. No. 06-0035, your modified diagram shows a valve that is not self-closing, but utilizes a double acting valve driven by a self-closing air valve. You ask for review of your modified diagram regarding compliance with provisions in§178.345-11(b)(2).

Section 178.345-11(a) requires cargo tank outlets, closures, and associated piping to be protected in accordance with § 178.345-8. In addition, § 178-345-11(b)(1) requires each cargo tank loading/unloading outlet be equipped with an internal self-closing stop-valve, or alternatively, with an external stop-valve located as close as practicable to the cargo tank wall. Each loading/unloading outlet must be fitted with a self-closing system capable of closing all such outlets in an emergency within 30 seconds of actuation. During normal operations the outlets may be closed manually. Under § 178.345-11(b)(2), bottom loading outlets that discharge lading into the cargo tank through fixed internal piping above the maximum liquid level of the cargo tank need not be equipped with a self-closing system.

It is the opinion of this Office that the valve depicted in the diagram accompanying your letter does conform to § 178.345-11(b)(2) provided it is connected to the emergency valve and closes the top of the tank.

I hope this answers your inquiry.


John A. Gale

Chief, Standards Development Standards

Office of Hazardous materials Standards


Regulation Sections

Section Subject
178.345-11 Tank outlets