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Interpretation Response #08-0025 ([HMT Associates, L.L.C.] [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:

Company Name: HMT Associates, L.L.C.

Individual Name: Mr. E.A. Altemos

Location State: VA Country: US

View the Interpretation Document

Response text:

February 25, 2008

Mr. E.A. Altemos

HMT Associates, L.L.C.

603 King Street, Suite 300

Alexandria, VA 22314-3105

Ref. No. 08-0025

Dear Mr. Altemos:

This is in response to your letter of October 2, 3007 requesting guidance regarding the requirements of the UN Manual of Tests and Criteria (UN Test Manual). Specifically, you request clarification regarding the test method for readily combustible solids (test method N.1). Your questions are paraphrased and answered as follows:

Q1) As referenced in, do the words "over the entire length of the sample" refer to the 100 mm length over which the test procedure in requires the burning rate to be measured, or to the entire 250 mm length of sample deposited on the test surface by the 250 mm long mould?

A1) The words "over the entire length of the sample" refer to the 100 mm length over which the test procedure in requires the burning rate to be measured. You will note that refers to the "rate of burning" and states "when the pile has burned a distance of 80 mm, measure the rate of burning over the next 100 mm."

Q2) The test manual procedure and classification criteria vary in certain respects depending on whether the material tested is a metal powder or whether it is a substance "other than a metal powder". Your guidance concerning the intent of the UN Test N.1 regarding the testing and classification of mixtures of metal powder and substances "other than metal powders" is requested.

A2) It is our opinion that a powder which is a mixture of metal powder and "other than metal" powder should be tested in accordance with the method described for metal powders. We do not believe the method as currently worded allows for a quantification of the risk based on the powder"s composition.

In your letter you also ask whether it may be necessary to seek clarification of the test method from the UN Sub-Committee of Experts on the Transport of Dangerous Goods. In our opinion, the text is clear with respect to the burning rate issue identified in your first question. However, we would not be opposed to considering an amendment clarifying the applicability of the test method to a powder which is a mixture of metal and "other than metal" powders if a majority of the Sub-Committee members are in agreement that such a clarification is necessary.

I hope this information is helpful. Please feel free to contact me if I can be of further assistance.


Edward T. Mazzullo

Director, Office of Hazardous Materials Standards

173.124, 173.125

Regulation Sections

Section Subject
173.124 Class 4, Divisions 4.1, 4.2 and 4.3-Definitions
173.125 Class 4-Assignment of packing group