# Keller and Heckman LLP — Hazardous Materials Safety Interpretation **Citation:** 02-0305 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2003-06-25 02-0305 response to Keller and Heckman LLP concerning 172.101. ## Document text <<>> of Transportation U.S. Department 400 Seventh St., S.W Washington, D.C. 20590 Special Programs Research and Administration Mr. Michael F. Morrone JUN 25 2003 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 microspheres 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 microspheres are non-friable, compressible, and flexible. Test data shows that these microspheres 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 microspheres by eliminating the flame spread and dust explosion hazards. The Dualite® products would be shipped in a sealed liner, inside a fiberboard box (4'X2'X2'). 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, III," in the § 172.101 Hazardous Materials Table (§ 172.101 HMT). 172.101 020305 <<>> 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, F46D1, F80SD1, 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, III," 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 ox 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 § 171.8. The microspheres most likely will meet the definition and description "Polymeric beads, expandable, Class 9, UN 2211, II" 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. Sincerely, Dem Hillo Delmer F. Billings Chief, Standards Development Office of Hazardous Materials Standards 02244 <<>> KELLER AND HECKMAN LLP 1001 G STREET, N. W. SERVINO BUSINESS THROUGH LAW AND SCIENCE° Engrum WASHINGTON, D.C. 20001 SUITE 500 WEST TEL. 202.434.4100 8172.101 FAx 202.434.4646 WWW.KHLAW.COM Applicability WRITER'S DIRECT ACCESS November 22, 2002 12-0305 Michael F. Morron morrone@khlaw.com 202) 434-412 Research and Special Programs Administration .S. Department of Transportatic ffice of Hazardous Materials Standards (DHM-1 400 Seventh Street, S.W. Washington, D.C. 20590-0001 Re: Request for Clarification - Dualite® Microsphere Products Dear Sir or Madam: polymeric microspheres that are coated with calcium carbonate for use in a wide variety of Our client, Sovereign Speciality Chemicals, Inc. (Sovereign), manufactures expanded miciationes, nukited at nubile caines, portin guquipso, and ani dinmaterials. These isobutane. The purpose of this letter is to request clarification of the applicability of the U.S. Department of Transportation's (DOT's) hazardous materials regulations to the shipment of Sovereign's Dualite® products. More specifically, we are requesting confirmation that these products do not fit within the listing for "Polymeric beads, expandable," UN 2211, found in 49 regula 172,101 and are not otherwise subject to regulation under the DOT hazardous materials Sovereign's Dualite® products consist of flexible, ultra-low density thermoplastic hollow microsphere cores that have been filled with gas (i.e., approximately 1.5 percent by weight of propane, isopentane, and/or isobutane) and surface coated with calcium carbonate. During the manufacturing process, these microspheres are "expanded" through heating. The microspheres 1 We discussed this issue with Ms. Hattie Mitchell of DOT's Office of Hazardous sues. After conferring with members of DOT's scientific staff, Ms. Mitchell suggested tha Laterials Standards during a recent telephone conversation regarding various classificatio because the referenced listing was vague, DOT would need to review a formal request for written clarification on the matter prior to offering any formal guidance on the applicability of the would not be unreasonable to expect that DOT might agree that the material may be shipped as a non-hazmat if it were packaged in airtight containers, assuming that the concentrations of gas are hazmat, we are submitting this letter. WASHINGTON, D.C. BRUSSELS SAN FRANCISCO <<>> Research and Special Programs Administration November 22, 2002 KELLER AND HECKMAN LIP Page 2 are non-friable, compressible, and flexible. They are resilient and impart a variety of valuable properties to end-use products, such as reduced weight and lower volatile organic compound (VOC) emissions. Based on test data and knowledge regarding the properties of the calcium carbonate materials do not fit within any of the DOT-specified hazard classes. In particular, the material coated microspheres that comprise the Dualite® products, Sovereign believes that these does not meet the definition of a Division 4.1 flammable solid as verified by burn rate testing. Furthermore, Sovereign has commissioned testing of Dualite® using the Hartman Dust Explosibility method and has found that the material is a non-combustible dust. The unique, and polymeric microspheres by eliminating the flame spread and dust explosion hazards. Less clear patented, calcium carbonate coating distinguishes Dualite® from unexpanded and uncoated is whether the material should be shipped as Class 9, "Polymeric beads, expandable." Because "evolving flammable vapor" with the corresponding listing, we are unclear as to whether the DOT regulations fail to define the term "expandable," other than by including the phrase microspheres, such as those that comprise the Dualite® products (i.e., ones that have been expanded, but some of which could theoretically undergo additional expansion), fall within the aforementioned listing and require shipment as a Class 9 material. Although the precise scope of the "Polymeric beads, expandable" listing is unclear under the DOT's hazardous materials regulatory regime, the International Maritime Dangerous Goods Code (IMDG Code) clarifies that the "Polymeric beads, expandable" name applies to materials that contain 5 to 8 percent of a volatile hydrocarbon that is predominantly pentane, and that release a small proportion of pentane to the atmosphere during storage. The Dualite® calcium carbonate coated microspheres have already been expanded, and they contain only approximately 1.5 percent by weight of volatile hydrocarbons (isobutene, isopentane, and/or propane, as compared to pentane), well below the 5 to 8 percent range described in the IMDG Code. (approximately 4 ft. x 2 ft. x 2 ft.). Due to the low volatile hydrocarbon content of the material Sovereign desires to ship the Dualite® products in a sealed liner, inside a fiberboard box products are not subject to regulation as Class 9 or any other hazard class material under the and using the IMDG Code definition as a reference, Sovereign believes that its Dualite® DOT hazardous materials regulations. Although there is the potential that a small quantity of flammable gas may be released from the material during the course of a particular shipment, we eleased would be so small that it would not create a flammable mixture with air, and as a resul elieve that given the small amount of flammable gas present in the microspheres, the quantit! would not be forbidden from transport by 49 C.F.R. § 173.21(g). In addition, and unlike unexpanded polymeric microspheres, the solid Dualite® material would not represent a flame spread /flammability hazard <<>> Research and Special Programs Administration Page 3 November 22, 2002 KELLER AND HECKMAN LIe Please advise whether you agree that Sovereign's Dualite products, as described, are not subject to regulation as a Class 9 or any other hazard class material. Should you have any questions or require further information, please do not hesitate to contact us. We look forward to receiving your response as soon as possible, so that Sovereign and its customers may ship these products accordingly. Sincerely, Michael F. Morrone S: 3901 ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `df13f890f88b110ac15b9444c100a44deb107a5c47f8b410644605a053801a16` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T21:54:25.129Z - Document slug: `phmsa-interpretation-02-0305` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Keller and Heckman LLP" ], "individuals": [ "Michael F. 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