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Interpretation Response #02-0305 ([Keller and Heckman LLP] [Michael F. Morrone])

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

Interpretation Response Details

Response Publish Date:

Company Name: Keller and Heckman LLP

Individual Name: Michael F. Morrone

Location State: DC Country: US

View the Interpretation Document

Response text:

JUN 25, 2003

Mr. Michael F. Morrone                                                   Ref. No.: 02-0305
Keller and Heckman LLP
1001 G. Street, N.W.
Suite 500 West
Washington, D.C. 20001

Dear Mr. Morrone:

This responds to your letter regarding applicability of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) to your client's products, "expanded polymeric microspheres". These micro spheres are marketed as Sovereign's Dualite® products and are used in a wide variety of applications, including automobile coatings, sporting equipment, and building materials. Subsequently, test data was provided for these products.

You provided information, as follows:

Your client's Dualite® products consists of flexible, ultra-low density thermoplastic hollow microsphere cores that have been filled with gas, approximately 1.5 percent by weight of volatile hydrocarbons (i.e., propane, isopentane, and/or isobutane), and surface coated with calcium carbonate. The microspheres are expanded through heating during the manufacturing process. The micro spheres are non-friable, compressible, and flexible. Test data shows that these micro spheres do not meet the definition for a Division 4.1 (flammable solid), and that the material is not combustible. The calcium carbonate coating distinguishes Dualite® products from unexpanded and uncoated polymeric micro spheres by eliminating the flame spread and dust explosion hazards.

The Dualite® products would be shipped in a sealed liner, inside a fiberboard box (4IX2'X2I). During transportation a small amount of flammable gas may be released, but would not create a flammable mixture with air, and thus would not be forbidden in accordance with § 173.21. The solid Dualite® material would also not represent a flame spread/flammability hazard.

You stated that because the HMR does not define the term "expandable", except that information in italics in the description specifies that such material produces "evolving flammable vapor," it is unclear as to whether Sovereign's Dualite® products (i.e., ones that have been-expanded, but some of which theoretically undergo additional expansion) fall within the description "Polymeric beads, expandable, Class 9, UN 2211, ill," in the § 172.1 01 Hazardous Materials Table (§ 172.1 01 HMT).

The test data provided indicates that certain of Sovereign's Dualite® products do not meet the definition in § 173.124 for a Division 4.1 (flammable solid) material, and if they do not meet any other hazard class definitions in Part 173, such products would not be subject to the HMR. However, the test data does indicate that certain of these products (e.g., Micropearl , F46Dl, F80SDl, and F82D) do meet the Division 4.1 (flammable solid) definition in § 173.124, and are subject to the HMR and regulated for purposes of transportation in commerce.

In regards to a material described as "Polymeric beads, expandable, Class 9, UN 2211, ill," in the § 172.101 HMT, a "miscellaneous hazardous material" (Class 9), as defined in § 173.140, is a material which presents a hazard during transportation but which does not meet the definition of any other hazard class. This includes: (1) Any material which has an anesthetic, noxious or other similar property which could cause extreme annoyance or discomfort to a flight crew member so as to prevent correct performance of assigned duties; or (2) Any material that is a hazardous substance, hazardous waste, or marine pollutant as defined in § l71.8.

The micro spheres most likely will meet the definition and description "Polymeric beads, expandable, Class 9, UN 2211, III" despite the word "Expandable". To get out of this entry, Sovereign needs to evaluate whether their material or product could evolve flammable gas. One way to evaluate is to conduct a "head space" test to see whether under certain transport conditions, "flammable atmosphere" can be created.

I hope this information is helpful. If we can be of further assistance, please contact us.


Delmer F. Billings
Chief, Standards Development
Office of Hazardous Materials Standards

Regulation Sections

Section Subject
172.101 Purpose and use of hazardous materials table