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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 #15-0022 ([Mihama Corporation] [MS. Andrea Kornbluth])

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

Interpretation Response Details

Response Publish Date:

Company Name: Mihama Corporation

Individual Name: MS. Andrea Kornbluth

Location State: DE Country: US

View the Interpretation Document

Response text:

July 29, 2015

Ms. Andrea Kornbluth
Regional Counsel, North America
Mihama Corporation
200 Bellevue Pkwy Ste 180
Wilmington, DE 19809

Reference No. 15-0022

Dear Ms. Kornbluth:

This is response to your December 30, 2014 e-mail requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to Department of Transportation (DOT) specification 39 (DOT-39) cylinders. In your letter, you reference a Worthington Cylinder Corporation petition (P-1622) that requested changes to the HMR related to the size limit for DOT-39 cylinders containing liquefied flammable gases. You state that you are unable to purchase standard size DOT-39 cylinders for use with refrigerant gases such as R-32. However, you are aware of cylinders currently being imported into the Japanese market from China on the basis of approval from the Authorized Testing Inc.'s Chinese offices. You state these cylinders are being certified without reference to the type of gas they will contain. You ask if it is an acceptable practice under the HMR to use these DOT-39 specification cylinders with a 793 cubic inch capacity certified in this way to ship UN 3252, refrigerant gas R32, classified as a 2.1 flammable gas.

Generally, R-32 refrigerant gases are classified as Liquefied Division 2.1 gases. The Pipeline and Hazardous Materials Safety Administration (PHMSA) does not believe it is a safe practice to ship 2.1 liquefied flammable gases in a DOT-39 cylinder exceeding 75 cubic inches.

Prior to 2002, § 173.304(a)(3), Note 9 appeared in the HMR and limited liquefied flammable gases in DOT-39 cylinders to a size of 75 cubic inches. In an October 20, 1998 (HM-220D) [63 FR 58460] Notice of Proposed Rulemaking (NPRM), PHMSA proposed to limit all liquefied flammable gases in DOT-39 cylinders to 75 cubic inches. This NPRM proposed to remove Note 9 from §173.304(a)(3) and apply the 75 cubic inch size limit on DOT-39 cylinders to all liquefied compressed gases (not just flammable) in 173.304(a)(3). PHMSA received several comments in opposition to extending the 75 cubic inch limit on DOT-39 cylinders to all liquefied compressed gases. PHMSA then published a Final Rule on August 8, 2002 (HM-220D) [67 FR 51625] and, based on comments received from the regulated community, decided not to expand the 75 cubic inch limit on DOT-39 cylinders containing liquefied compressed gases. However, in the process of publishing the Final Rule, PHMSA inadvertently deleted Note 9 in § 173.304a that limited liquefied flammable gases in DOT-39 cylinders to 75 cubic inches. It was never the intention of PHMSA to remove the 75 cubic inch limit for liquefied flammable gases in DOT-39 specification cylinders. PHMSA did receive and accept a petition (P-1622) from Worthington Cylinders to address this error in a future rulemaking.

I hope this satisfies your request.



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

173.304(a)(3), 173.304a

Regulation Sections

Section Subject
173.304 Filling of cylinders with liquefied compressed gases