# Carleton Technologies, Inc. — Hazardous Materials Safety Interpretation **Citation:** 04-0277 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2005-02-07 04-0277 response to Carleton Technologies, Inc. concerning 173.306. ## Document text <<>> of Transportation U.S. Department 400 Seventh St., S.W. Washington, D.C. 20590 Research and pecial Program: dministratior FEB 7 2005 Ms. Amy Vollmer Reference No.: 04-0277 Product Manager - Missiles Team Carleton Technologies, Inc. 10 Cobham Drive Orchard Park, NY 14127-4195 Dear Ms. Vollmer: This is in response to your letter requesting clarification of the limited quantity exception for "Helium, compressed, 2.2, UN 1046" under the Hazardous Materials Regulations (HMR; 49 CFR parts 171-180). Your letter states that the helium is in cylinders with a capacity of 6.9 cubic inches, at a pressure of 9,200 psig. When transported by highway, § 173.306(a)(1) excepts limited quantities of certain compressed gases, including compressed helium, from labeling (except when intended for further transportation by air) and the specification packaging requirements when packaged in containers of not more than 4 fluid ounces capacity (7.22 cubic inches or less). Each package must conform to the general requirements in §S 173.24 and 173.24a, and may not exceed 30 kg (66 pounds) gross weight. In addition, limited quantity shipments of compressed helium must meet all other requirements in the HMR from which they have not been excepted. There are no restrictions on the internal pressure when the container has a capacity of 4 ounces or less. However, as a guideline, it is recommended that the container has a ratio of burst pressure to normal operating pressure comparable to the most similar DOT specification packaging. For packagings not comparable to a DOT specification packaging, a ratio of burst pressure to normal operating pressure of five is recommended. Finally, if part number B45625-1 contains a hazardous material, the material must be properly packaged, marked and described in accordance with the applicable HMR requirements. I am returning your drawings marked proprietary which were submitted to this office for review. I hope this satisfies your request. Sincerely, Hattie L. Mitchell Chief, Regulatory Review and Reinvention Office of Hazardous Materials Standards Coolanan 173-306 0)() 040277 <<>> Carleton Technologies Inc 10 Cobham Drive Carleton Aerosystems Betts Telephone: 716-662-0006 Orchard Park, New York 14127-4195 www.carltech.com Fax: 716-662-0747 $173.306(() December 1, 2004 Compressed Gusesin Cylinders 400 7th street SW U.S. Department of Transportation 04-0217 Washington, DC 20590-0001 Attention: Director, Office of Hazardous Material Standards Edward Mazzullo USDOT/RSPA, DHM-10 Reference: Request for Letter of Interpretation Dear Mr Mazzullo: level) and B45749-1 (filled bottle assembly level) to ship under CFR 49 section 173.306 limited Carleton Aerosystems requests a letter of interpretation on p/n B45625-1 (final assembly and shipped quantities of compressed gas. The part number in question is B45749-1 a welded cylinder 6.9 cubic inches in volume and will be filled with compressed Helium, UN1046, at 9200 psi. Helium has a Hazard class of 2.2. had discussed this interpretation with Transportation Regulation Specialist Helen Engrum and For a product previously shipped from Carleton, John Szymanski our design/development engineer from Hattie Mitchell). This letter confirmed that our part number B44637-1 fell under section 176.306 Mechanical Engineer Mark Toughiry (reference letter dated Feb 27, 2003, reference number 03-0029 regulations "when in containers of not more that 4 fluid ounces capacity (7.22 cubic inches or less)... Limited Quantities of compressed gases section (a)(1). Section (a)(1) provides exception to most assembly also contains a pressurized reservoir which is less than 7.22 cubic inches in volume and Our request is to have a letter of interpretation for our files for our new part number B45625-1. This drawings for both the top level shippable item and for the filled gas reservoir. If you require any we want to confirmation that this part falls under section 176.306 section (a)(1). Enclosed are the additional information please let me know. (716) 667-6482 Regards, (.../ Amy Vollmer vollmer@carltech.com Product Manager- Missiles Team encl. - A Cobham plc company .. ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `5854876bb751e98d650f8e465a06061fa19fe79b9c8f836d255a1ee5183f27cc` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T04:59:47.059Z - Document slug: `phmsa-interpretation-04-0277` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Carleton Technologies, Inc." ], "individuals": [ "Ms. Amy Vollmer" ], "refIds": [ "04-0277" ], "catalogDates": [ "2005-02-07" ], "catalogParts": [ 173 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/50071" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "173.306", "173.306(a)(1)", "173.24", "173.24a", "176.306" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/173306" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2004/040277.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2004/040277.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2004/040277.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/04-0277-8158b45808.pdf", "pdfArtifactSha256": "aaa8c19f47540affb720fc1b02f8a1a6493458038938a6f8a6f9be5b834ad653", "extractedTextPath": "data/sources/phmsa-interpretations/04-0277-8158b45808.v2.txt", "extractedTextSha256": "a10529f1d5186d32c7a35454ad7c51014048a323a799ff6f1b7c290b4dde896a", "pageCount": 2, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```