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Interpretation Response #05-0212 ([Truck Trailer Manufacturers Association] [Mr. Jeff Sims])

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

Interpretation Response Details

Response Publish Date:

Company Name: Truck Trailer Manufacturers Association

Individual Name: Mr. Jeff Sims

Country: US

View the Interpretation Document

Response text:

Oct 28, 2005


Mr. Jeff Sims                      Reference No. 05-0212
TTMA Engineering Manger
Truck Trailer Manufacturers Association
1020 Princess Street
Alexandria, VA 223 14-2247

Dear Mr. Sims:

This is in response to your letter dated September 2, 2005 concerning a letter issued on, April 7, 2004 (Ref No.: 04-0055) that retracted a letter issued on, September 25, 2003 (Ref No.: 02-0287). The retracted letter permitted the vent on top of a cargo tank at the double bulkhead to be plugged, provided the drain was left open. Specifically, you request that we reinstate the September 2 2003 letter, to permit vents to remain plugged.

The purpose of the vent in question is to allow vapors to escape to the atmosphere. The physical properties of gasoline vapors prohibit venting through the drain at the bottom of the tank because gasoline vapors, like most vapors, are lighter than air and will rise to the top or the tank. To provide adequate ventilation and drainage, the cargo tank must be vented to the atmosphere and the bottom drain must be kept open at all times (see § 178.345-1(i)(2)). Therefore, based on the requirement in § 178.345-1(i)(2), we are not reinstating the September 25, 2003 letter.

I hope this information is helpful. Please contact us if you require additional assistance.



John A. Gale
Chief, Standards Development
Office of Hazardous Materials Standards


Regulation Sections

Section Subject
178.345-1 General requirements