{"operation":"document","citation":"04-0203","title":"Chemical Accident Reconstruction Services, Inc. — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2005-03-18","effective_on":null,"summary":"04-0203 response to Chemical Accident Reconstruction Services, Inc. concerning 173.306.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-04-0203.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-04-0203.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-04-0203","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2004/040203.pdf","body":"<<<PAGE 1>>>\n\nU.S. Department\nof Transportation\n400 Seventh Street, S.W.\nWashington, D.C. 20590\nPipeline and\nHazardous Materials Safety\nAdministration\nMAR 18 2005\nMr. Michael Fox\nRef. No. 04-0203\nChemical Accident Reconstruction Services, Inc.\n9121 E. Tanque Verde Road, # 105\nTucson, Arizona 85749\nDear Mr. Fox:\nThis is in response to your letter and subsequent telephone conversation with a member of my\nstaff and Mr. Staniszewski of our Office of Hazardous Materials Technology requesting\nclarification on the testing requirements of aerosol containers, DOT 2P or 2Q under the\nHazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you request\nclarification of the provisions in § 173.306(a)(3)(ii). We apologize for the delay in responding\nand any inconvenience it may have caused\nSection 173.306(a)(3)(ii) requires a metal aerosol container to be capable of withstanding\nwithout bursting a pressure of one-and-one-half times the equilibrium pressure of the content at\nwithstanding the specified pressure. You may demonstrate that the container meets the standard\n130° F. The HMR do not specify a method for demonstrating that the container is capable of\nby testing or design specifications.\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nChief. Standards Developmer\nOffice of Hazardous Materials Standards\n173.306 (a)3)\n040203\n(1i)\n\n<<<PAGE 2>>>\n\nChemical Accident Reconstruction Services, Inc.\n511313286(\nAugust 28, 2004 (Via First Class Mail) & October 4, 2004 (via Certified Mail)\nU.S. Department of Transportation\nOffice of Hazardous Materials Standards\nATTN: Director\nWashington, D.C 20590\nSecond Reguest\nRe: 49 CFR 173.306(a)(3)(11)\nDear Director:\nIt is my understanding from reviewing the subject DOT Regulations that containers for\nlimited quantities of compressed gas, such as aerosol containers,\n\"must be capable of withstanding without bursting a pressure of one and\none-half times the equilibrium pressure of the content at 130F\"\nFrom my experience in testing many hundreds of aerosol containers I have learned that\nthe pressure at which an aerosol container will burst depends upon the test method used.\nFor example, I recently tested a DOT 2Q container using a hydro tester. If precautions\nare taken to remove all the air prior to a hydro test, there is no compressed gas (or\nenergy) inside the container. Under these conditions, the container will very slowly\ndeform as the pressure is increased. Each time the container deforms, the pressure drops\nand stops the deformation. Using hydro testing on a DOT 2Q container, the bottom\nbulged at 250 psig but did not fail until 390 psig. Since the DOT 2Q specification for\nburst pressure is 270 psig, the container passed the test.\nFor the product described above, I know the temperature-pressure behavior of the product\nin the container very well as I have measured it several different ways.\nWhen I heat the aerosol product to bursting, I find that the bottom snaps out at 250 psig\nind then the bottom instantaneously explodes off. Obviously, the kinetic energy of th\nspecification for a 2Q container\nThe dilemma is obvious. Using the hydro test method, I could assert that the container\nmore than meets DOT specifications for a 2Q container. However, testing with the\nproduct in the container and using heat to increase pressure, I would be forced to\nconclude that the container does not meet DOT 2Q specifications.\n9121 E. Tanque Verde Road #105, Tueson, Arizona 85749\n800-MIKE-FOX (645-3369)\nFax: 520-749-0861\n\n<<<PAGE 3>>>\n\nSince the regulation itself [49 CFR 173.306(a)(3)(ii)] refers to the \"equilibrium pressure\nof the content at 130F\" it would seem that the heating test would be more appropriate as\nit directly involves the content inside the container. It would also make more sense from\na safety viewpoint, as the hydro test would over-estimate the actual safety of the\ncontainer-content combination. In other words, if the hydro test was used to determine if\nthe container meets DOT Regulations, that could conceivably put unsafe container-\ncontent combinations into transportation.\nYour help in clarifying this dilemma would be greatly appreciated.\nThank you for your assistance.\nSincerely,\nMICHAEL FOX 10/02/04\nMichael Fox, Ph.D.\nFounder\nPage 2 of 2","truncated":false,"body_characters":4303}