# Haas TCM — Hazardous Materials Safety Interpretation **Citation:** 04-0023 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2004-05-05 04-0023 response to Haas TCM concerning 173.27. ## Document text <<>> IS.Departmen f Transportation 00 Seventh Street, S.V lashington, D.C. 2059 Special Programs Research and MAY 5 2004 Administration Mr. Larry Holcombe Haas TCM Account Manager Ref. No.: 04-0023 1646 West Chester Pike West Chester, PA 19382 Dear Mr. Holcombe: This responds to your letter concerning determination of the vapor pressure to calculate the test pressure for packages intended for air transportation in § 173.27 of the Hazardous Materials below: Regulations (HMR; 49 CFR Parts 171-180). Your questions are paraphrased and answered Q1. Is it correct to obtain the vapor pressure from engineering tables if the liquid consists of a single chemical component? Al. Yes, obtaining the vapor pressure for a liquid that consists of a single chemical component from engineering tables is acceptable. Q2. For liquids with multiple chemical components, you propose to use vapor pressure from pressure threshold limit equal to 50% of minimum test pressure for the package. If the vapor engineering tables for the most volatile component at the specified temperature and set a vapor pressure of the mixture exceeds the threshold limit, you further propose to measure the vapor pressure by laboratory testing. You ask if this approach is suitable. A2. We are unable to determine the suitability of your approach. The Hazardous Materials Regulations do not prescribe specific methods for determining the vapor pressure. The vapor desi may bad the packa by ising or of viticstanding the pressure regattements in 8 17327 without leakage may be used. I hope this determination is helpful. Sincerely, Hithe a mitthel Hattie L. Mitchell Chief, Regulatory Review and Reinvention Office of Hazardous Materials Standards 173.27 040023 <<>> Haas TCM 1646 West Chester Pike haas West Chester, PA 19382 Phone: (610) 436-9840 Fax: (610) 436-9076 (800) 220-4227 www.haascorp.com Corbin January 23, 2004 §173.27 Frits Wybenga Air U.S. Department of Transportation Deputy Associate Administrator 04-0023 DHM-1 400 7th St., S.W. Washington, DC 20590-0001 202-366-0656 RE: 49 CFR 173.27 General requirements for transportation by aircraft Dear Deputy Wybenga: Part 173.27 of 49 Code of Federal Regulations requires that shippers ensure that containers of regulations include using the vapor pressure of the liquid at specified temperatures (50 or 55 regulated liquids do not leak under conditions of air shipment. The methods stated in the degrees Celsius) to determine container pressure capacities. obtaining the needed vapor pressure data. We request your Department's advice on the suitability of our proposed approach, below, for 1. Where the liquid consists of a single chemical component we propose to use engineering tables to obtain the vapor pressure of the component at the specified temperatures. 2. Where the liquid consists of multiple chemical components we propose to select the most volatile component and use engineering tables to obtain the vapor pressure of that Since the regulations specify a minimum packaging capacity (14 psig or 11 psi epending on the liquid, 49 CFR 173.27 c) 2) i)), we propose to set a threshol packaging requiremessure estimates equal to 50% of the minimum value for b. Any engineering estimate of a mixture that exceeds the threshold limit vapor vapor pressure. pressure will automatically be set aside for laboratory testing to measure the 3. We propose to run a pilot program to test the suitability of this approach. A sub-sample of the liquids where engineering estimates are made (per steps 1. and 2. above), and The vapor pressure determined by the two methods, i.e., engineering estimate and lab which were below the threshold limit will also be tested in the lab for the vapor pressure. test, will be used to calculate the required packaging <<>> Frits Wybenga January 23, 2004 Page 2 4. This approach of using a combination of engineering estimates and lab testing will be 100% on the packaging requirements. considered suitable if the pilot shows that both engineering estimates and lab tests agree Thank you. Sincerely, Imme Fund for Larry Holcombe Haas TCM Account Manager ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `ceb206d88c946edbf4605465d253dd24eab7ca1153d77d410d6f1931c10ae741` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T11:51:43.982Z - Document slug: `phmsa-interpretation-04-0023` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Haas TCM" ], "individuals": [ "Mr. Larry Holcombe" ], "refIds": [ "04-0023" ], "catalogDates": [ "2004-05-05" ], "catalogParts": [ 173 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/45246" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "173.27" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/17327" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2004/040023.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2004/040023.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2004/040023.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/04-0023-ae08d65043.pdf", "pdfArtifactSha256": "c99cbcb89f351c77807d361cb80de324b905d5039d5d5175d5ec2744c4806d40", "extractedTextPath": "data/sources/phmsa-interpretations/04-0023-ae08d65043.v2.txt", "extractedTextSha256": "a53c051cd88e1ed1d0b208cad9c6d367dbd342e5d80dde5b76220dfd44e3b78a", "pageCount": 3, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```