Interpretation Response #07-0012 ([HMT Associates] [Mr. E. A. Altemos])

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

Interpretation Response Details

Response Publish Date: 02/23/2007

Company Name: HMT Associates

Individual Name: Mr. E. A. Altemos

Location State: DC Country: US

View the Interpretation Document

Response text:

Feb 23, 2007

Mr. E. A. Altemos                      Reference No. 07-0012

HMT Associates

603 King St., Suite 300

Alexandria, VA 22314-3105

Dear Mr. Altemos:

This is in response to your letter requesting clarification of the applicability of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) to gas sensors containing a small amount of a Class 8 (corrosive) material. You ask whether these articles are regulated under the HMR.

According to your letter, the sensors contain two electrodes separated by a thin layer of electrolyte and connected by a low resistance external current. The electrolyte is contained within a matting to prevent the flow of liquid. The sensor produces a current from a chemical reaction on contact with the gas it is designed to detect. The current is proportional to the concentration of the gas the sensor is designed to detect and can be measured across a load resistor in the external circuit. Gas diffusing into the sensor causes oxidation or reduction, which generates a low current that flows through the external circuit. You state that the electrolytes vary in the sensors; however, the Class 8 (corrosive) material (phosphoric or sulphuric acid) never exceeds 1 milliliter and if the sensors are punctured, no corrosive liquid will flow from the devices. You also state that there is no energy in the sensors when being transported and no risk of heat generation or sparking.

It is our determination that the hazardous material contained in the gas sensors, as described in your letter, with no more than 1 milliliter of Class 8 (corrosive) material (phosphoric or sulphuric acid), is not transported in a quantity or form that poses a risk to health and safety or property during transportation. Therefore, the gas sensors are not subject to regulation under the HMR.

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

Sincerely,

Hattie L. Mitchell

Chief, Regulatory Review and Reinvention

Office of Hazardous Materials Standards

173.136(b)

Regulation Sections