PHMSA Response Letter

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May 23, 2016

Mr. Richard Maruya
President
A.S. Trust & Holdings
44-129 Mikiola Drive
Kaneohe, HI 96744

Reference No. 15-0231

Dear Mr. Maruya:

This is in response to your November 24, 2015 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the packaging requirements for HCR188C/R441A and HCR188C/R443A refrigerant gases.  As previously stated in a letter of interpretation, Ref. No. 14-0169 (see attached letter), you plan to ship the refrigerants as “UN1965, Hydrocarbon gas mixture, liquefied, n.o.s., Division 2.1.” We have summarized and answered your questions below.

Q1.  Can a DOT 39-400 cylinder be used for these HCR188C refrigerants?

A1.  The answer is yes.  In accordance with 49 CFR 173.304, HCR188C/ R441A and HCR188C/R443A may be packaged in specification DOT 39 cylinders with a service pressure of 400 p.s.i. provided all of the applicable requirements of the HMR are met, including, but not limited to, filling limits prescribed in §§ 173.304 and 173.304a.  As stated in the letter of interpretation, Ref. No. 14-0169, § 173.304(b) states the liquid portion of a liquefied gas may not completely fill the packaging at any temperature up to and including 55 °C (131 °F).  In addition, the filling density for any cylinder containing these materials can be determined by calculating the percent ratio of the weight of the gas in the packaging to the weight of the water the container will hold at 16 °C (60 °F).  See “Note 1” of § 173.304a(a)(2).

It is important to note that 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 1.23L (75 cubic inches).  In an October 20, 1998 (HM-220D) [63 FR 58460] Notice of Proposed Rulemaking (NPRM), PHMSA inadvertently removed the 75 cubic inch limit for liquefied flammable gases in DOT 39 cylinders.  PHMSA has received and accepted a petition (P-1622) from Worthington Cylinders to address this error in a future rulemaking.

Q2.  Is a DOT 39-400 equipped with a standard pressure relief cap acceptable for flammable refrigerants at this time?

A2: In accordance with § 173.301(f)(4), a pressure relief device (PRD) is required on a specification DOT 39 cylinder regardless of cylinder size or filled pressure. A specification DOT 39 cylinder used for liquefied Division 2.1 materials must be equipped with a metal PRD.  Fusible PRDs are not authorized on specification DOT 39 cylinders containing liquefied gas.  Furthermore, in accordance with § 173.301(f)(1), a specification DOT 39 cylinder filled with R443A and R441A would need to comply with the requirements specified in CGA  S-1.1/CGA S-7.  As you stated in your incoming letter, CGA Publication S-1.1 does not specifically identify your commodity.  However, based on the component gases that make up the mixtures  R441A or R443A, and following the procedure outlined in CGA S-7, it is determined that a rupture disk CG-1 type PRD or CG-7 type pressure relief valve PRD may be used with your R441A and R443A liquefied compressed gases.

I trust this information is helpful.  Please feel free to contact this office if you need further assistance.

Sincerely,

Duane A. Pfund
International Standards Coordinator
Standards and Rulemaking Division

173.304, 173.304a, 173.304(b), 173.304a(a)(2), 173.301(f)(4), 173.301(f)(1)