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Interpretation Response #12-0213 ([Senior Mechanical Engineer] [Mr. Mark Fazzio])

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

Interpretation Response Details

Response Publish Date:

Company Name: Senior Mechanical Engineer

Individual Name: Mr. Mark Fazzio

Location State: NC Country: US

View the Interpretation Document

Response text:

December 18, 2012

Mr. Mark Fazzio
Senior Mechanical Engineer
UTC Aerospace Systems
4200 Airport Drive
Wilson, NC 27896
Ref. No.: 12-0213

Dear Mr. Fazzio:

This is in response to your September 11, 2012 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) as they pertain to UN1044, fire extinguishers.  In your letter you describe two, DOT specification 39 cylinders with a volumetric capacity of 11.7 (cu in) and 19.6 (cu in) and an operating pressure of 1225 psi.  It is your understanding that these cylinders should be shipped as UN1044, fire extinguisher.

The HMR do not authorize the use of DOT specification 39 cylinders as UN1044, fire extinguishers.  When transported, each cylinder must be described with the name of its compressed gas contents and the outside package must be properly marked and labeled in accordance with Part 172.

The requirements for shipping fire extinguishers are found in § 173.309.  Paragraph (a) of this section permits the use of non-specification cylinders charged with a limited quantity of compressed gas to not more than 241 psig.  Such fire extinguishers are excepted from labeling, unless shipped by aircraft and the specification packaging requirements when shipped under the conditions described in § 173.309(a)(1) through (a)(3).  If the requirements of § 173.309(a) cannot be met, a DOT specification 3A, 3AA, 3E, 3AL, 4B, 4BA, 4B240ET, or 4BW (§§ 178.36, 178.37, 178.42, 178.46, 178.50, 178.51, 178.55, and 178.61) cylinder must be used in accordance with § 173.309(b).

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


Delmer Billings
Senior Regulatory Advisor
Standards and Rulemaking Division


Regulation Sections

Section Subject
173.309 Fire extinguishers
178.36 Specification 3A and 3AX seamless steel cylinders
178.37 Specification 3AA and 3AAX seamless steel cylinders
178.42 Specification 3E seamless steel cylinders
178.46 Specification 3AL seamless aluminum cylinders