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The United States Pipeline and Hazardous Materials Safety Administration (“PHMSA”) addressed in a November 30, 2023, interpretive response a question regarding the Hazardous Materials Regulations (“HMR”) application to Reference No. 23-0058.

PHMSA was responding to a request from Carbochem Inc. (CI”) of Wynnewood, Pennsylvania.

CI indicated that chemically activated carbon is often shipped as a Division 4.2 (Spontaneously Combustible Material) material due to its self-heating properties. The company informed PHMSA that to determine the classification of its product, it arranged for its Carbochem activated carbon grades to be tested using United Nations (UN) Test N.4 “Test method for self-heating substances,” in accordance with Section 33.3.1.6 of the UN Manual of Test and Criteria (UNMTC).

The results of the testing are stated to indicate that Carbochem DC-50 (steam activated) exhibits no self-heating. Carbochem CA-50 (chemically activated) is stated to show some self-heating. However, not self-heating at 140 degrees C with a 25mm cube sample.

CI asked whether such test results accurately determine that its Carbochem products should not be classified as Division 4.2 hazardous materials.

PHMSA responds that in accordance with § 173.22 of the HMR, it is the shipper’s responsibility to properly classify a hazardous material. Nevertheless, PHMSA states as follows:

. . . based on the test data and and certification you provided, we agree that your company's products—as described in your email—do not meet the definition of a Division 4.2 hazardous material.

The agency further states that if such products do not meet any other hazard class as defined in part 173 then they are not a hazardous substance, hazardous waste, or marine pollutant and, therefore, not subject to the HMR.

A copy of the November 30th interpretive letter can be downloaded here.