# Buck Research Instruments, LLC — Hazardous Materials Safety Interpretation **Citation:** 00-0133 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2000-11-06 00-0133 response to Buck Research Instruments, LLC concerning 172.101. ## Document text <<>> U.S. Department of Transportation NOV - 6 2000 Washington, D.C. 20590 400 Seventh St., S.W. Special Programs Research and Administration Mr. John Buetow President and CEO Ref. No. 00-0133 5375 Western Ave. Buck Research Instruments, LIC Boulder, CO 80301 Dear Mr. Buetow: This responds to your letter and telephone conversation with Dr. George Cushmac of the Office of Hazardous Materials Technology regarding the applicability of the Hazardous Materials Regulations (HMR; 49 CER Parts 171-180) to your ionization cells that contain a trace amount of nitric oxide. You intend to offer these cells to air carriers for domestic and international air transportation and it is your opinion that they should be excepted from the HMR. You state that the ionization cells are used in a Lyman-alpha thick glass tubes which are 1" long and 3" in diameter. hygrometer, a humidity measuring instrument, and are made of tube contains a trace (1/47.5 of an atmosphere) Each oxide under vacuum. Ten tubes are placed in an intermediate packaging with cushioning and then placed into a strong, corrugated outer packaging. In your opinion, if the tubes were to break or leak while in transportation, the nitric oxide would immediately mix with air and be rendered nontoxic. Under the HMR, nitric oxide is classed as a Division 2.3 toxic gas. However, it is also our opinion that because of the trace amount of nitric oxide in each tube and the manner in which it is packaged, the tubes would not pose a significant hazard to health during transportation and, therefore, are not subject to the HMR. I trust this satisfies your request. we can be of further assistance. Please contact us again if Sincerely, Elen Pa mirzalle Edward I. Director, Office of Hazardous Materials Standards <<>> or ransomeone NOV - 6 2000 Washington, D.C, 20590 400 Seventh St., S.W. Mr. John Buetow Ref. No. 00-0133 Buck Research Instruments, LLC President and CEO 5375 Western Ave. Boulder, CO 80301 Dear Mr. Buetow: Dr. George Cushmac of the Office of Hazardous Materials I'his responds to your letter and telephone conversation witt •Technology regarding the applicability of the Hazardous Materials that contain a trace amount of nitric oxide. Regulations (HMR; 49 CFR Parts 171-180) to your ionization cells these cells to air carriers for domestic and international air transportation and it is your opinion that they should be excepted from the HMR. You state that the ionization cells are used in a Lyman-alpha thick glass tubes which are 1" long and 3" in diameter. hygrometer, a humidity measuring instrument, and are made of Each tube contains a trace (1/47.5 of an atmosphere) amount of nitric oxide under vacuum. Ten tubes are placed in an intermediate packaging with cushioning and then placed into a strong, corrugated outer packaging. In your opinion, if the tubes were to break or leak while in transportation, the nitric oxide would immediately mix with air and be rendered nontoxic. Under the HMR, nitric However, it is also our opinion that because of the trace oxide is classed as a Division 2.3 toxic amount of nitric oxide in each tube and the manner in which it is packaged, the tubes would not pose a significant hazard to health during transportation and, thereforé, are not subject to the HMR. I trust this satisfies your request. Please contact us again if we can be of further assistance. Sincerely, Elean 7 Mazalle Director, Office of Hazardous Materials Standards 00-0133 <<>> RBt menas luc Stevens 172,101 Nitrit Oxide April 25, 2000 00-0133 Edward Mazzullo US Department of Transportation Research and Special Programs Administration Office of Hazmat Safety 400 7th Street SW Washington D.C. 20590 Dear Mr. Mazzullo: Pran vins eu regrdingepackage vas sendin by oite ai atmospheric enelo ngeng in lsmy The regulation cited was the nitric oxide, compressed listing in the hazmat table (HMR 49 CFR 172.101 and UN 1660), which is for large, highly pressurized, metal cylinders of nitric oxide (NO). The regulation forbids transport of NO cylinders by air because NO is a hazatd class 2.3 gas poisonous by inhalation as defined by HIMR 49 CFR 173.115. Based upon the evidence I am presenting in this letter about the size of the NO ionization cells, the amount of NO involved, the opinion of George Cushmac of RSPA, the steps we go through to protect the cells in transit, the cells' end use and the number of years they have been used without incident, I am asking for a letter of clarification of the regulations that states that these NO ionization cells are not subject to this regulation and can be safely transported via aircraft. The NO ionization cells are thick glass tubes that are 1" long and ¾" in diameter. These cells are first evacuated to 10-5 Torr, then backfilled with 16 Torr of NO, which is roughly 1/50th of an atmosphere. I have would be sucked into them, diluting the NO concentration. If the tubes were to break, it is the opinion of enclosed drawings of the tubes to show the volume of gas involved. If the tubes were to develop a leak, air George Cushmac (202-366-4493) of RSPA that the amount of NO contained within the tubes is insufficient to cause a danger to anyone and that they would be safe to transport by air. We package the tubes to protect them from breakage by first wrapping the individual tubes in bubble wrap. Then we put the wrapped tubes into a coffee can and fill any voids with additional bubble wrap and/or stryofoam peanuts. Then we put the coffee can into a thick, corrugated cardboard box. Buck Research Instruments, LLC and the manufacturer (Glass Technologists of Annapolis, MD) have regularly shipped these detector tubes for a total of 25+ years. In that time, we have never had a tube break in transit. The NO ionization cells are used to detect ultraviolet light in a Lyman-alpha hygrometer, which is a high-speed humidity measurement instrument originally developed in 1960 by the Naval Research Lab. The Lyman-alpha hygrometer has been used worldwide ever since by universities and atmospheric research agencies (e.g. NÅSA, NOAA and NCAR) on hundreds of different research aircraft. There has never been a safety issue with any of the people flying the research aircraft about having the NO ionization cells on their aircraft. We want to make certain that we are working within the rules and regulations of the US DOT. Therefore we are asking for this letter of interpretation. Please expedite your reply. Sincerely, Joh e Bauctrs John Buetow President and CEO 5375 Western Ave. - Boulder, CO 80301 • Tel: 303-442-6055 • Fax: 303-443-2986 • 1-800-HUMIDITY • email: info@hygrometers.com • Web: http://www.hygrometers.com <<>> Rames LAc Stevia 172.161 Witrit Oxide Apal 25, 2000 00-0133 US Department of Transportation Edward Mazzullo Research and Special Progtams Administration 4007ch Street SW Office of Hazmat Safety Washington D.C. 20590 Dear Mr. Mazzullo: I am waiting you regarding a package I was sending by air to an atmospheric research agency in Germany. The transport of NO cylinders by air because NO is a hazard class 2.3 gas poisonous by inhalation as defined by ionization cells, the amount of NO involved, the opinion of George Cushmac of RSPA, the steps we go HMR 49 CFR 173.115. Based upon the evidence I am presenting in this letter about the size of the NO through to protect the cells in transit, the cells' end use and the number of years they have been used without not subject to this regulation and can be safely transported via aircraft. incident, I am asking for a letter of clarification of the regulations that states that these NO ionization cells ate The NO ionization cells are thick glass tubes that are 1" long and %" in diameter. These cells are first evacuated to 10-5 Tors, then backfilled with 16 Torr of NO, which is roughly 1/50h of an atmosphere I have would be sucked into them, diluting the NO concentration. If the tubes were to break, it is the opinion of enclosed drawings of the tubes to show the volume of gas involved. If the tubes were to develop a leak, air cause a danger to anyone and that they would be safe to transport by aix George Cushmac (202-366-4493) of RSPA that the amount of NO contained within the tubes is insufficient to Then we put the wrapped tubes into a coffee can and fill any voids with additional bubble wrap and/or We package the tubes to protect them from breakage by first wrapping the individual tubes in bubble wrap. stryofoam peanuts. Then we put the coffee can into a thick, corrugated cardboard box. Buck Research Instruments, LLC and the manufacturer (Glass Technologists of Annapolis, MD) have regularly shipped these detector tubes for a total of 25+ years. In that time, we have never had a tube break in transit. humidity measurement instrument oxiginally developed in 1960 by the Naval Research Lab. The Lyman-alpha The NO ionization cells are used to detect ultraviolet light in 2 Lyman-alpha hygrometer, which is a high-speed NOAA and NCAR) on hundreds of different research aircraft. There has never been a safety issue with any of hygrometer has been used worldwide ever since by universities and atmospheric research agencies (eg. NASA, the people flying the research aircraft about having the NO ionization cells on their aircraft. are asking for this letter of intespretation. Please expedite your reply. We want to make certain that we are working within the rules and regulations of the US DOT. Therefore we Sincerely. John Buetow President and CEO 5375 Western Ave, • Boulder, CO 80301 • Tel: 303-442-6055 • Fax: 303-443-2986 • 1-800-HUMIDITY • email: info@hygrometers.com • Web: http://www.hygrometers.com <<>> DETECTOR - LYMAN ALPHA SILVER CHLORIDE BOND (Model No. GT 203D) MAGNESIUM FLUORIDE WINDOW ROUNDED END 13 O.D. × 1MM THK , EVAPORATED METAL COATING 22 MM 9MM$0.5 PYREX FILL DETECTOR WITH 3 16MM NITRIC OXIDE (NO) - 30 MM +— 12 MM ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `6cc5f3efd82369f788d4604d45c14d8d5ecee0139adb7718a701e1a9093a683b` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T21:17:34.531Z - Document slug: `phmsa-interpretation-00-0133` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Buck Research Instruments, LLC" ], "individuals": [ "Mr. John Buetow" ], "refIds": [ "00-0133" ], "catalogDates": [ "2000-11-06" ], "catalogParts": [ 172 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/59306" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "172.101", "173.115", "172.161" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/172101" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2000/000133.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2000/000133.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2000/000133.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/00-0133-9f17c2be0b.pdf", "pdfArtifactSha256": "91ba853d7f51aab1e2c32215872fc0f888cc9950be25c37f30682f7de8cce3b5", "extractedTextPath": "data/sources/phmsa-interpretations/00-0133-9f17c2be0b.v2.txt", "extractedTextSha256": "b560a3817bd30fcafc1a5f570e49773b45c2e81f8bcd7bb22e2fefbbe65ef8f7", "pageCount": 5, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```