# Department of California Highway — Hazardous Materials Safety Interpretation **Citation:** 99-0040 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 1999-03-02 99-0040 response to Department of California Highway concerning 177.840. ## Document text <<>> U.S. Department of Transportation Washington, D.C. 20590 400 Seventh Street, S.W. Research and MAR 2 1999 Special Programs Administration Mr. Paul Horgan Ref. No. 99-0040 Department of California Highway Patrol P.O. Box 942898 Sacramento, CA 94298 Dear Mr. Horgan: This is in reference to our conversation on February 3, 1999, concerning the proper orientation for loading certain DOT 4L cylinders which are being used in oxygen, refrigerated liquid service. The requirements in 49 CFR 173.316(c) and 177.840(a)(1) specify that DOT 4L cylinders must be loaded (on a motor vehicle) in an upright position. The cylinders in question were designed and constructed to be used and transported with the longitudinal axis of the cylinders positioned, horizontally. Because of the unique design of these DOT 4L cylinders, the vapor space is along the longitudinal axis of the cylinder. Therefore, it is this office's determination that these cylinders are "upright" when they are transported in a horizontal position, as the safety relief devices are in communication with the vapor space of the cylinder. This type of positioning enables the pressure relief devices to function and protect the cylinder in a safe manner as intended. Accordingly, we find that the transportation of these cylinders in a horizontal position conforms with the requirements in §§ 173.316(c) and 177.804(a)(1). We proposed a revision to § 177.804(a)(1) in a recent notice of proposed rulemaking (RSPA 98-3684 HM-220; October 30, 1998). I hope this information is helpful. If we can be of further assistance, please contact this office. Sincerely, Hitte z, Mitchell Hattie L. Mitchell Chief, Regulatory Review and Reinvention Office of Hazardous Materials Standards <<>> .... MAR 2 1999 Mr. Paul Horgan Ref. No. 99-0040 Department of California Highway Patrol P.Ó. Box 942898 Sacramento, CA 94298 Dear Mr. Horgan: This is in reference to our conversation on February 3, 1999, concerning the proper orientation for loading certain DOT 4L cylinders which are being used in oxygen, refrigerated liquid service. The requirements in 49 CFR 173.316(c) and 177.840(a)(1) specify that DOT 4L cylinders must be loaded (on a motor vehicle) in an upright position. The cylinders in question were designed and constructed to be used and transported with the longitudinal axis of the cylinders positioned, horizontally. Because of the unique design of these DOT 4L cylinders, the vapor space is along the longitudinal axis of the cylinder. Therefore, it is this office's determination that these cylinders are "upright" when they are transported in a horizontal position, as the safety relief devices are in communication with the vapor space of the cylinder. This type of positioning enables the pressure relief devices to function and protect the cylinder in a safe manner as intended. Accordingly, we find that the transportation of these cylinders in a horizontal position conforms with the requirements in §§ 173.316(c) and 177.804(a)(1). We proposed a revision to § 177.804(a)(1) in a recent notice of proposed rulemaking (RSPA 98-3684 HM-220; October 30, 1998). I hope this information is helpful. If we can be of further assistance, please contact this office. Sincerely, Hattie L. Mitchell Chief, Regulatory Review and Reinvention Office of Hazardous Materials Standards Hmitchell:DHM-12:2/11/99:cdd File: 177.840(a), 173.316 <<>> Requester Paul Horgan Date Received: 2/12/99 Company Department of California Highway patrol Tracking Number: 99-0040 Phone Revision Date: 2/12/99 Date Assigned 2/12/99 Date of Letter 2/3/99 Staff Mitchell First Draft Due: 3/5/99 Section 173.316(c) First Draft Date: 2/12/99 Subject Cylinders Concurrence Status Status Date Sign Date Signor HBPO Copy to Docket Copy to DHM-60 Comment ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `0dd67f148876847d27ca3e6931b73fb99758762b5cb531af6865b29e73f072b2` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T06:26:41.378Z - Document slug: `phmsa-interpretation-99-0040` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Department of California Highway" ], "individuals": [ "Mr. Paul Horgan" ], "refIds": [ "99-0040" ], "catalogDates": [ "1999-03-02" ], "catalogParts": [ 177 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/68471" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "177.840", "177.840(a)(1)", "173.316(c)", "177.804(a)(1)" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/177840" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990040.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990040.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1999/990040.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/99-0040-39136ebeff.pdf", "pdfArtifactSha256": "e4809b3c744923c853f2ea8838842836a20177bb407cd4ce94aacb2c74acf8f6", "extractedTextPath": "data/sources/phmsa-interpretations/99-0040-39136ebeff.v2.txt", "extractedTextSha256": "66039f7ad4a90d522b539c2d56770c40885d106d5692cdb062dc8f1589350c27", "pageCount": 3, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```