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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 #07-0028 ([Line Pressures, Inc.] [Mr. Paul Graves])

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

Interpretation Response Details

Response Publish Date:

Company Name: Line Pressures, Inc.

Individual Name: Mr. Paul Graves

Location State: DC Country: US

View the Interpretation Document

Response text:

May 21, 2007

Mr. Paul Graves                                         
Reference No. 07-0028
Line Pressures, Inc.
3900 South Lipan Street
Englewood, Colorado 80110-4422

Dear Mr. Graves:

This is in response to your January 19, 2007 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) concerning the transportation of refrigerated liquefied gases. Your questions are paraphrased and answered below.

Q1. Does the HMR, as amended on December 29, 2006 (71 FR 78627), require orientation markings to be placed on a DOT 3-series cylinder containing Nitrous oxide? Would a DOT 4L cylinder containing Nitrogen, refrigerated liquid be considered an "open cryogenic receptacle"?

Al. The answer is no to both questions. Section 172.312(a) requires each non-bulk
package having inner packagings containing liquid hazardous materials, "single packaging fitted with vents, or an open cryogenic receptacle intended for the transport of refrigerated liquefied gases to be packed with closures upward, and legibly marked, with package orientation markings on two opposite vertical sides of the package. DOT 3 cylinders are not cryogenic receptacles and are not authorized for refrigerated liquid. A DOT 4L cylinder is a closed cryogenic receptacle.

Q2. Is a pressure relief device considered to be a vent?

A2. The answer is no. The term "vent" as used in § 172.312(a) applies to non-bulk packages other than cylinders.

Q3. If "20 cylinders" and an additional "20 cylinders" of a different size containing the same hazardous material are offered into transportation, would it be correct to enter the total quantity of hazardous materials on the shipping paper as "40 cylinders".

A3. The answer is yes. Section 172.202(a)(5) requires the total quantity of hazardous materials covered by the description to be indicated on a shipping paper (by mass or volume, or by activity for Class 7 (radioactive) materials and must include an indication of the applicable unit of measurement for example, "200 kgs." or "50 L." However, this requirement is not applicable to cylinders, provided some indication of the total quantity is shown, such as “40 cylinders” as used in your example above.

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


Charles E. Betts
Senior Transportation Specialist
Office of Hazardous Materials Standards

171.8, 172.202, 172.312(a)

Regulation Sections

Section Subject
171.8 Definitions and abbreviations
172.202 Description of hazardous material on shipping papers
172.312 Liquid hazardous materials in non-bulk packagings