# Department of the Air Force — Hazardous Materials Safety Interpretation **Citation:** 06-0004 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2006-01-24 06-0004 response to Department of the Air Force concerning 172.504. ## Document text <<>> JAN 24 2006 TSgt. Jesse Rubalcaba Ref. No.: 06-0004 Command Section Evaluator Department of the Air Force 20 AF/LGMM 6610 Headquarters Drive F.E. Warren AFB, WY 82005-3943 Dear TSgt. Rubalcaba This is in response to your letter requesting clarification of the placarding requirements under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask if the exception from placarding in § 172.504(c), for less than 454 kg (1001 pounds) aggregate gross weight of hazardous materials covered by Table 2 of § 172.504(e), applies to the Division 2.2 material in cylinders. You indicate that the cylinders are loaded on a single transport vehicle and weigh approximately 4,800 pounds. The placarding exception in § 172.504(c) applies to the aggregate gross weight of all non- bulk packagings on a single transport vehicle that are covered by Table 2 of § 172.504(e) and do not fall under the provisions of § 172.505. As defined in § 171.8, the phrase "gross weight" is the weight of a packaging plus the weight of its contents. In your scenario, the aggregate gross weight is equivalent to the aggregate weight of all cylinders and the Division 2.2 material they contain. Therefore, given that the aggregate gross weight of your cylinders is approximately 4,800 pounds, the transport vehicle must be placarded. I hope this information is helpful. Please contact us if you require additional assistance. Sincerely, he A. Gale Office of Hazardous Materials Standards 172.504 060004 <<>> TO: Office of Hazardous Material Standards, Research and Special Programs Administration DHM-10, U.S. Department of Transportation 400 7th Street SW, Washington, DC 20590-001 FROM: 20 AF/LGMM 6610 Headquarters Drive F. E. Warren AFB WY 82005-3943 SUBJECT: Request interpretation of 49 CFR 172.504 General Placard Requirements 1. A request of interpretation is needed for the following DOT placarding requirements, 49 CFR 172, Subpart F., 172.504, (c). Step (c) states. " placards are not required on-(1) A transport vehicles or freight container which contains less than 454 kg (1001 pounds) aggregate gross weight of hazardous materials covered by table 2 of paragraph (e) of this section." 2. The transported vehicle in question is a 16 cylinder 4500 PSI cascade breathable bottled system weighing approximately 4800 Ibs. This syster is made up of 16 DOT bottles (P/N AC444), which are connected to each other using inter-connecting whips. The air bottles are attached horizontally to an approved DOT storage rack using zinc plated steel cylinder retaining brackets. The entire unit is installed on an open flat bed trailer. 3. When in transport, all air bottles are closed and the remainder of the system is bled. The unit is covered using a black canvas tarp which is used to protect the system from the elements. With the cover installed, the hazard is not identifiable to the public or first responders. 4. Different interpretations exist of whether the unit should be placarded. In one view, due to the definition of gross weight, the bottle cylinder weight plus the content in the bottle accounts for the 1001 pound weight requirements, and it would require placarding. In a second view, only the content in the bottle should account for the 1001 pound requirements for placarding, and the unit would not require placards. Does this unit require placards or not? GUARDIANS OF THE HIGH FRONTIER <<>> 5:000 this section." c. Section 171.8, Definitions and abbreviations: "Gross weight or gross mass means the weight of the packaging plus the weight of its contents." "Freight container means a reusable container having a volume of 64 cubic feet or more, designed and constructed to permit being lifted with its contents intact and intended primarily for containment of packages (in unit form) during transportation." 6. Any questions regarding this letter can be directed to TSgt Jesse Rubalcaba, 20 AF/LGMM, 307-773-5636, fax 307-773-5419. Thanks for your assistance. stink ESSE RUBALCABA, TSgt, USAF Command Section Evaluator TOTAL P.03 ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `4fc9b0e8af6d285c4840d85be0ab4c2be440010eae2c6f5d91eff0ef6ac78243` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-25T00:55:04.641Z - Document slug: `phmsa-interpretation-06-0004` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Department of the Air Force" ], "individuals": [ "TSgt. Jesse Rubalcaba" ], "refIds": [ "06-0004" ], "catalogDates": [ "2006-01-24" ], "catalogParts": [ 172 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/47016" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "172.504", "172.504(c)", "172.505", "171.8" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/172504" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2006/060004.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2006/060004.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2006/060004.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/06-0004-98f4615b84.pdf", "pdfArtifactSha256": "4e20cc73f7ed36ce34a060bcc86d67b2d4a66d3ec7daafee6d81ae96680d27c7", "extractedTextPath": "data/sources/phmsa-interpretations/06-0004-98f4615b84.v2.txt", "extractedTextSha256": "948e07ad3b2bc55c3359d1f5d2fe040661cf6e3dae8a6d1a843d07365877683d", "pageCount": 3, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```