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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 #08-0154 ([Symmetricom] [Mr. Gerald M. Beauchesne])

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

Interpretation Response Details

Response Publish Date:

Company Name: Symmetricom

Individual Name: Mr. Gerald M. Beauchesne

Location State: MA Country: US

View the Interpretation Document

Response text:

June 25, 2008

Mr. Gerald M. Beauchesne

Facility Manager


34 Tozer Road

Beverly, MA 01915-5510

Ref. No. 08-0154

Dear Mr. Beauchesne:

This responds to your May 16, 2008 letter requesting an update of an interpretation you received from the Office of Hazardous Materials Regulation of the Research and Special Program Administration (RSPA), the predecessor agency to the Pipeline and Hazardous Materials Safety Administration, regarding the applicability of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) to a device containing rubidium. Specifically, you request clarification on an interpretation indicating the device containing rubidium does not pose a transportation hazard as a flammable solid and whether the interpretation can be extended to Class 4 hazardous materials.

You provide a copy of the letter your company received in November 1984 stating the opinion of the Office that "a frequency standard (device) containing less than one gram of rubidium does not pose a transportation hazard as a flammable solid and consequently is not regulated as such." You also indicate that your company continues to produce frequency devices with less than one gram of rubidium for use in atomic clocks. Finally, in telephone conversations with our Office, you state that tests conducted by your company on components of the devices in which the glass cells or lamps containing rubidium are broken do not show spontaneous ignition or flammability when exposed to air or water.

Based on the information provided and on previous interpretation by RSPA, it is the opinion of this Office that a frequency device containing less than one gram of rubidium for use in atomic clocks is not subject to the HMR as a Class 4 hazardous material.

I hope this information is helpful. Please contact us if you require additional assistance.


John A. Gale,

Chief, Standards Development

Office of Hazardous Materials Standards


Regulation Sections

Section Subject
173.124 Class 4, Divisions 4.1, 4.2 and 4.3-Definitions