{"operation":"document","citation":"25-0026","title":"Entegris Inc. — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2025-05-27","effective_on":null,"summary":"25-0026 response to Entegris Inc. concerning 171.22, 172.101.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0026.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0026.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0026","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2025-05/250026.pdf","body":"<<<PAGE 1>>>\n\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\nMay 27, 2025\nJim V. McManus\nSr. Principal Engineer\nDangerous Goods Safety Advisor (DGSA)\nEntegris Inc.\n7 Commerce Drive\nDanbury, CT 06810\nReference No. 25-0026\nDear Mr. McManus:\nThis letter is in response to your March 5, 2025 email requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to the proper shipping name\n(PSN) for “UN2036, Xenon, compressed” as listed in the § 172.101 Hazardous Materials Table\n(HMT). Specifically, you ask for clarification regarding the appropriate use of the qualifying\nword “compressed” in association with the PSN for transport of xenon based on your\nunderstanding the word was removed under the rulemaking “Harmonization With the United\nNations Recommendations, International Maritime Dangerous Goods Code, and International\nCivil Aviation Organization’s Technical Instructions” (HM-215E).1\nYour questions are paraphrased and answered below:\nQ1. For domestic shipments, is “Xenon, compressed” the PSN for UN2036?\nA1. Yes. The PSN for xenon (UN2036) was revised to read “Xenon, compressed” in the\n§ 172.101 HMT for consistency with PSNs for other compressed gases (i.e., other inert\ngases) in the rulemaking “Hazardous Materials: Revision to Requirements for the\nTransportation of Battery-Powered Devices; and Harmonization With the United Nations\nRecommendations, International Maritime Dangerous Goods Code, and International\nCivil Aviation Organization’s Technical Instructions” (HM-224D/HM-215J) that\npostdated final rule HM-215E.2 Therefore, for purposes of the HMR, the PSN for xenon\n(UN2036) includes the qualifier “compressed.”\n1 68 FR 44992 (Jul. 31, 2003).\n2 74 FR 2200 (Jan. 14, 2009).\n\n<<<PAGE 2>>>\n\nQ2. As authorized by § 171.22(a), may a shipment of xenon offered for transport in\naccordance with the International Maritime Dangerous Goods Code for export from the\nUnited States use the PSN “Xenon” for UN2036, instead of “Xenon, compressed?”\nA2. Yes.\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nDirk Der Kinderen\nChief, Standards and Development Branch\nStandards and Rulemaking Division\n\n<<<PAGE 3>>>\n\nS Specialty y Gas s and d Engineered d Materials\n7 Commerce Drive\nDanbury, CT 06810\nwww.entegris.com\nHorne, T,\n25-0026\nMarch 5, 2025\nStandards and Rulemaking Division\nPipeline and Hazardous Materials Safety Administration, Attn: PHH-10\nU.S. Department of Transportation\nEast Building\n1200 New Jersey Avenue, SE\nWashington, DC 20590-0001\ninfocntr@dot.gov\nRe: Request for Interpretation\nDear Sir or Madame;\nPursuant to 49 CFR § 105.20, this letter is being submitted by e-mail to PHMSA to request an interpretation\non several questions we have pertaining to the correct shipping name for UN2036.\nCurrently the Hazardous Materials Table (HMT) in 49 CFR § 172.101 lists the proper shipping name for\nUN2036 as Xenon, compressed.\nThe Xenon we are shipping is not a refrigerated liquid, but is Xenon gas packaged in a DOT specification\ncylinder under pressure and therefore is assigned the identification number UN2036 from column 4 of\nthe HMT.\nIt is also noted that the United Nations Recommendations on the Transport of Dangerous Goods (UN\nModel Regulations), International Maritime Dangerous Goods Code (IMDG Code), the International Civil\nAviation Organization's Technical Instructions for the Safe Transport of Dangerous Goods by Air (ICAO\nTechnical Instructions) and Transport Canada's Transportation of Dangerous Goods Regulations (TC TDG\nRegulations) use the proper shipping name Xenon, without the qualifying word “compressed” for\nUN2036.\nUN Model Regulations 12th Edition (2001) Change in Shipping Name for UN2036\nBefore the 12th revised edition of the UN Model Regulations, the UN Model Regulations, IMDG Code, ICAO\nTechnical Instructions and TC TDG Regulations assigned the proper shipping name Xenon, compressed to\nUN2036.\nAfter reviewing past changes to the UN Model Regulations it was discovered that the 11th revised edition\nof the UN Model Regulations was amended by removing the qualifying word “compressed” from 11\nentries in the Dangerous Goods List. UN2036 was one of the entries.\n\n<<<PAGE 4>>>\n\nThe word “compressed” was removed from those entries as a consequence of a change to the definition\nof a non-liquefied compressed gas and a liquefied compressed gas in the UN Model Regulations.\nThe definition for these types of gases was adjusted such that any gas which is partially liquid above\n-50 °C (-58 °F) is defined as a “liquefied compressed gas” and gases which remain completely gaseous at\nor above -50 °C (-58 °F) are defined as a “non-liquefied compressed gas”. Effectively then, any gas with a\ncritical temperature (Tc) above -50 °C (-58 °F) would be considered a liquefied compressed gas and those\ngases with a critical temperature at or below -50 °C (-58 °F) are ones that cannot exist as a liquid above\n-50 °C (-58 °F) as they remain in a completely gaseous state and are considered a non-liquefied compressed\ngas.\nPrior to the 12th edition of the UN Model Regulations, 20 °C (68 °F) was used instead of -50 °C (-58 °F) as\nthe reference temperature to delineate between a non-liquefied compressed gas and a liquefied\ncompressed gas. Thus any gas with a critical temperature less than 20 °C (68 °F), such as Xenon (Tc = 16.6\n°C) would be entirely gaseous at 20 °C and therefore meet the old definition of a non-liquefied compressed\ngas. Apparently, it has been customary to use the qualifying word “compressed” in addition to the name\nof a gas, if the gas is a non-liquefied compressed gas. This is currently the case for sixteen non N.O.S.\nentries in the HMT (e.g., UN1066 Nitrogen, compressed).\nSubsequent to the UN amendments, the other international standards and regulations were revised to\nremove the word “compressed” from the 11 entries.\nResearch and Special Programs Administration Final Rule HM-215E (July 31, 2003)\nOn July 31, 2003, the Research and Special Programs Administration (RSPA) of the U.S. DOT issued the\nFinal Rule HM-215E which served to maintain alignment of the HMR with certain international standards,\nincluding the 12th revised edition of the UN Model Regulations. The Final Rule stated the following\nregarding the removal of the qualifying word “compressed” from the proper shipping name of eleven\nentries in the Hazardous Materials Table:\n\n<<<PAGE 5>>>\n\nAfter a review of the above eleven entries in the current Hazardous Materials Table, we have confirmed\nthe qualifying word “compressed” has been removed from ten of the eleven entries with the exception\nbeing UN2036 which still states the proper shipping name as “Xenon, compressed”.\nRSPA further stated in the Final Rule HM-215E that the reason for the change was due to a change in the\nHMR to the definitions for a non-liquefied compressed gas and a liquefied compressed gas.\nThe figure below shows the definitions in the HMR for a non-liquefied compressed gas and a liquefied\ncompressed gas before and after the Final Rule HM-215E\n\n<<<PAGE 6>>>\n\nShould the word “compressed” be associated with the shipping name for UN2036\nIt seems as if there is merit to consider removing the word compressed from the proper shipping name\nfor UN2036 in a future rulemaking as Xenon meets the definition of a liquefied compressed gas as it has\na critical temperature of 16.6 °C (-61.9 °F). This change in the HMR would also provide the benefit of\npromoting harmonization with the international standards and regulations.\nI do note if this change was made, it may be necessary to provide a transitional provision for\nimplementing use of the revised shipping name. For example, HM-215E provided a 4 year transition\nperiod to adopt the new shipping names for the gases where the qualifying word compressed was\nremoved. This translational provision was included in 49 CFR § 171.14 (d)(5) in the October 1, 2003\nversion of 49 CFR.\nEntegris Questions\nQuestion 1\nNotwithstanding the difference in the proper shipping name for UN2036 between 49 CFR and the\ninternational standards and regulations, is the proper shipping name for domestic shipments of UN2036\nin the United States Xenon, compressed?\nQuestion 2\nFor shipments of Xenon made in accordance 49 CFR § 171.22 (a), in that they are shipped in compliance\nwith the International Maritime Dangerous Goods Code (IMDG Code) and are being exported from the\nUnited States to an international destination, can the proper shipping name Xenon be used for UN2036\ninstead of Xenon, compressed.\nI appreciate PHMSA’s attention to this matter and look forward to your response.\nSincerely,\nJ J J J J J J J J (Ji ) V M MJames (Jim) V. McManus\nSr. Principal Engineer\nDangerous Goods Safety Advisor (DGSA)\nEntegris Inc.\nPhone: 203-482-1606","truncated":false,"body_characters":8875}