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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 #14-0229 ([The Chlorine Institute] [Ms. Robyn Kinsley])

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

Interpretation Response Details

Response Publish Date:

Company Name: The Chlorine Institute

Individual Name: Ms. Robyn Kinsley

Location State: VA Country: US

View the Interpretation Document

Response text:

Ms. Robyn Kinsley
Director, Transportation
The Chlorine Institute
1300 Wilson Blvd., Suite 525
Arlington, VA 22209

Reference No. 14-0229

Dear Ms. Kinsley:

This is in response to your November 18, 2014 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) relating to a tell-tale indicator on a combination pressure relief device for a rail tank car. You ask if, in accordance with HMR § 179.100-13(a) the outlet for a tell-tale indicator which has a threaded outlet must be closed with an approved screw plug during transportation.

The requirement to close a tell-tale indicator having a threaded outlet with an approved screw plug does apply. The requirements for pressure relief devices are found in HMR § 179.15. For a combination pressure relief system, § 179.15(e)(2) requires that a tell-tale indicator be closed during transportation. The combination pressure relief system designed with a tell-tale indicator must be in compliance with the AAR approved design when utilizing a screw plug in the closed position.

I trust this information is helpful. If you have further questions, please do not hesitate to contact this office.


Duane A. Pfund
International Standards Coordinator
Standards and Rulemaking Division

Regulation Sections

Section Subject
179.100-13 Venting, loading and unloading valves, measuring and sampling devices
179.15 Pressure relief devices