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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 #11-0117 ([Worthington Cylinders] [Mr. Steve Gentry])

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

Interpretation Response Details

Response Publish Date:

Company Name: Worthington Cylinders

Individual Name: Mr. Steve Gentry

Location State: OH Country: US

View the Interpretation Document

Response text:

June 13, 2011



Mr. Steve Gentry

Worthington Cylinders

1085 Dearborn Drive

Columbia, Ohio 43085

Reference No.: 11-0117

Dear Mr. Gentry:

This responds to your May 12, 2011 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the internal capacity limits and pressure relief devices (PRD) required for Specification Department of Transportation (DOT) 39 cylinders intended to contain a Division 2.1 liquefied compressed gas.

Specifically, in your letter, you state that you plan to ship a Division 2.1 liquefied compressed gas, HFO-1234yf, that you have classified as "UN3161, Liquefied gas, flammable, n.o.s. (2,3,3,3-Tetrafluoroprop-1-ene)" in a specification DOT 39 cylinder. We have paraphrased your questions and answered them below.

Q1: Can HFO-1234yf be packaged in specification DOT 39 cylinders of any volume capacity as long as the service pressure and test pressure of the cylinder are in accordance with the applicable specifications?

A1: HFO-1234yf may be packaged in specification DOT 39 cylinders; however, there are limits on the volume capacity of these cylinders. As previously stated in a letter of interpretation, Ref. No. 11-0052 (see attached letter), the filling requirements for liquefied compressed gases in DOT specification cylinders are based on the type of gas contained in the cylinder and are found in § 173.304a of the HMR. In addition,

§ 173.304a(a)(2) provides a table listing various types of liquefied gases and their corresponding maximum permitted filling densities. Based on your incoming letter, the material you wish to ship is not specifically listed in the table in this section. For gases not specifically listed in the table in § 173.304a(a)(2), the filling density can be determined using the formula provided in "Note 1" to that Table. Therefore, the filling density for any cylinder containing your material, including a specification DOT 39 cylinder, 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 oC (60 oF).

Please note that, in accordance with § 178.65, cylinders built to meet a DOT 39 specification may not have a maximum water capacity that exceeds 55 pounds (1,526 cubic inches) for cylinders with service pressure of 500 p.s.i.g. or less, and 10 pounds (277 cubic inches) for cylinders with service pressure in excess of 500 p.s.i.g.

Q2: If HFO-1234yf can be packaged in specification DOT 39 cylinders, what PRD should be used?

A2: As stated in A1, HFO-1234yf may be packaged in specification DOT 39 cylinders provided certain filling requirements are met. In addition, in accordance with

§ 173.301(f)(4), a 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 HFO-1234yf would need to comply with the requirements specified in CGA Publication S-1.1. As you stated in your incoming letter, CGA Publication S-1.1 does not specifically identify your commodity. CGA Publication S-1.1 does, however, mandate a CG-7 PRD for other similar liquefied compressed gases and it is the opinion of this Office that cylinders containing HFO-1234yf must be fitted with a CG-7 PRD.

I hope this satisfies your inquiry. Please contact us if we can be of further assistance.


T. Glenn Foster

Chief, Regulatory Review and Reinvention Branch

Standards and Rulemaking Division

173.301, 173.304a

Regulation Sections

Section Subject
173.301 General requirements for shipment of compressed gases and other hazardous materials in cylinders, UN pressure receptacles and spherical pressure vessels
173.304a Additional requirements for shipment of liquefied compressed gases in specification cylinders
178.65 Specification 39 non-reusable (non-refillable) cylinders