Approval of explosives under the HMR

This responds to your letter regarding the approval of explosives under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask whether your client's product (surge arresters) containing a small amount (2.8 grams) of a Division 5.1, Packing Group II hazardous material (potassium chlorate), is excepted from the explosive approval process prescribed in § 173.56. Additionally, it is your understanding that the negligible risk posed by your client's product in transportation should except it from the HMR under the conditions described in your letter.

Under §173.56(i) of the HMR, the Associate Administrator for Hazardous Materials Safety may specify a classification or except an explosive material from the requirements of the HMR. We agree with your client's assessment that because there is no explosion when the surge arrester is activated, and the surge arrester can only be activated by a high-level of predetermined electric current, the product is not subject to the explosive approval and classification process under § 173.56. We find, however, that your client's product would more appropriately be described as "Dangerous goods in apparatus, Class 9, UN3363," and packaged in accordance with § 173.222. Under Special provision 136 assigned to the entry "Dangerous goods in apparatus," in column 7 of the Hazardous Materials Table, the small quantity of potassium chlorate (2.8 grams) in each surge arrester qualifies for the small quantity exceptions found in § 173.4 and, when packaged in accordance with § 173.222, is excepted from the HMR.