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Interpretation Response #12-0030 ([U.S. Department of Defense, Attn: AMSSD-SA] [Mr. Elias V. Cantu])

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

Interpretation Response Details

Response Publish Date:

Company Name: U.S. Department of Defense, Attn: AMSSD-SA

Individual Name: Mr. Elias V. Cantu

Location State: IL Country: US

View the Interpretation Document

Response text:

May 22, 2012


Mr. Elias V. Cantu
Safety Manager, Military Surface Deployment and Distribution Command
U.S. Department of Defense, Attn: AMSSD-SA
One Soldier Way,
Scott AFB, IL 62225

Ref. No. 12-0030

Dear Mr. Cantu:

This responds to your January 24, 2012 letter regarding the applicability of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) to a device that contains a compressed gas. According to your letter, a Raman cell ("the cell") contains methane gas pressurized at 1,000 to 1,200 psig and has a volume of 2.7 cm3. The cell was proof tested to a safety factor of 2 times the maximum operating pressure (MOP) (i.e., 2,400 psig) without structural failure and a structural analysis shows a safety factor greater than 4 times the MOP (i.e., 4,800 psig). The cell is contained in a sealed laser unit lens and located near the housing for a resonator. By your calculations, if a structural failure allowing a leak from the cell were to occur in the lens housing or were to leak into the resonator housing, the percentage concentrations for methane are estimated at 0.8% and 47%, respectively, which are outside the bounds of the explosive limits for methane gas (i.e., 5% to 15%). You indicate that although highly unlikely, a partial leak in a concentration within the explosive limits could occur. In a telephone conversation with a member of my staff, you indicated that ignition of this minute amount of methane gas would be equivalent to the energy released from striking a match. Specifically, you ask for clarification whether the cell containing the compressed methane gas is subject to the HMR.

PHMSA regulates the transportation in commerce of materials it determines are hazardous in that "the amount and form [of the material] may pose an unreasonable risk to health and safety or property." 49 U.S.C. 5103, as delegated to PHMSA in 49 CFR 1.53(b). Based on the information provided in your letter and subsequent telephone conversation, the Raman cell is not shipped in a quantity and form that poses an unreasonable risk to health and safety or property during transportation and, therefore, is not subject to regulation under the HMR.

I hope this information is helpful. If you have further questions, please contact this office.



Ben Supko
Acting Chief, Standards Development Branch
Standards and Rulemaking Division

171.1, 172.101

Regulation Sections

Section Subject
171.1 Applicability of Hazardous Materials Regulations (HMR) to persons and functions
172.101 Purpose and use of hazardous materials table