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The United States Pipeline and Hazardous Materials Safety Administration (“PHMSA”) addressed in an April 8th Interpretive Letter a question regarding the Hazardous Materials Regulations (“HMR”) applicable to the use of United Nations (UN) identification number and proper shipping name “UN1396, Aluminum powder, uncoated.”
PHMSA was responding to a February 11th correspondence from Teledyne Scientific & Imaging (“Teledyne”).
The question Teledyne posed was whether there is a particle size limit with respect to the use of this hazardous materials description.
PHMSA replied in the negative, noting that:
…While certain hazardous materials descriptions and proper shipping names in the § 172.101 Hazardous Materials Table (HMT) limit use of the entry (e.g., a concentration range, particle size, energy capacity, etc.), the entry for “UN1396, Aluminum powder, uncoated” does not specify limiting criteria for particle size.
The agency further notes that the test method in the U.N. Manual of Tests and Criteria do not specify a particle size. It further states that hazardous materials that may be dangerous when wet (as an example, uncoated aluminum powder) are classified based on the results of testing irrespective of particle size (citing UN Test N.5, Test method for substances which in contact with water emit flammable gases, see Section 33.5 of the UN Manual of Tests and Criteria).
By way of caveat, PHMSA does note that as provided in § 173.22, it is the shipper’s responsibility to properly classify and describe a hazardous material based on the classification criteria provided in the HMR.
A copy of the Interpretive Letter can be downloaded here.
