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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 #18-0117

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

Interpretation Response Details

Response Publish Date:

Company Name: BOC Fire & Gas

Individual Name: Ms. Lisa J. Nugent

Location State: AR Country: US

View the Interpretation Document

Response text:

February 27, 2019

Ms. Lisa J. Nugent
Jacobs Suppression Tech
BOC Fire & Gas
Mail Stop P.O. Box 340137
Deadhorse, AK  99734
Reference No. 18-0117

Dear Ms. Nugent:

This letter is in response to your August 14, 2018, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to cylinders.  Specifically, you seek confirmation of your understanding that the phrase in § 180.205(c) that states, “may remain in service until it is emptied,” is an allowance—instead of a requirement—as it applies to the inspection, installation, testing, and maintenance of fire suppression systems containing cylinders that conform to the International Fire Code (IFC).  You note that the IFC requires DOT 3AA cylinders used in carbon dioxide systems to be removed from service in 12-year intervals for hydrostatic testing. 

Your understanding is correct.  The HMR do not define the phrase “may remain in service until it is emptied”; however, under § 180.205(c) of the HMR, PHMSA allows a cylinder to be used to transport the product it contains until it is emptied, provided the cylinder continues to meet all applicable requirements.  There is no time limit on how long a charged cylinder may stay in service before it must be requalified under the HMR, but once emptied, a cylinder due for requalification may not be refilled and offered for transportation unless it has been requalified in accordance with Part 180, Subpart C of the HMR.  Further, a cylinder with a specified service life may not be refilled and offered for transportation after its authorized service life has expired. 

While a DOT specification cylinder containing a hazardous material need not be emptied to meet a testing schedule under the HMR, Federal and state agencies may have differing requirements or testing intervals for cylinders used in certain non-transportation applications.  You should comply with both state and federal laws, as applicable. 

I hope this information is helpful.  Please contact us if we can be of further assistance.


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

180.205(c), 180

Regulation Sections

Section Subject
180.205 General requirements for requalification of specification cylinders