# Smarter Sorting — Hazardous Materials Safety Interpretation **Citation:** 21-0065 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2021-09-23 21-0065 response to Smarter Sorting concerning 173.120, 173.150. ## Document text <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, DC 20590 September 23, 2021 Mr. AJ Kenny Director of Regulations Smarter Sorting 4901 East Cesar Chavez Street Austin, TX 78702 Reference No. 21-0065 Dear Mr. Kenny: This letter is in response to your June 15, 2021, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to exceptions for aqueous solutions of alcohol. Specifically, you ask whether the condition of 24 percent or less alcohol by volume in the § 173.150(e)(1) exception applies to all alcohols in the aqueous solution or just to the flammable alcohol(s) in the aqueous solution. Furthermore, you provide the following example of an aqueous solution and ask whether the solution is eligible for the § 173.150(e)(1) exception: • Aqueous solution has a flashpoint of 54 °C and meets the definition of a flammable liquid (Class 3) (as specified in § 173.120(a)); • 20 percent of the solution is isopropanol, which is an alcohol and has a flashpoint of 12 °C (i.e., a flammable alcohol); • 20 percent of the solution is glycerol, which is an alcohol and has a flashpoint of 175 °C (i.e., a non-flammable alcohol); and • The remaining components in the solution do not meet the definition of a hazardous material. The 24 percent or less alcohol by volume condition in the § 173.150(e)(1) exception applies to flammable alcohols. Thus, the example of the aqueous solution you outlined above would be eligible for the exception in § 173.150(e)(1). As detailed in § 173.150(e)(1), “an aqueous solution containing 24 percent or less alcohol by volume and no other hazardous materials may be reclassed as a combustible liquid.” The original intent of this exception was to provide relief for aqueous solution of alcohols that do not meet the definition of a hazard class other than a flammable liquid (Class 3). <<>> Therefore, while the solution itself contains 40 percent alcohol, the criteria for the § 173.150(e)(1) exception should be based on the alcohol(s) that meets the definition of a flammable liquid (Class 3). I hope this information is helpful. Please contact us if we can be of further assistance. Sincerely, Dirk Der Kinderen Chief, Standards Development Branch Standards and Rulemaking Division <<>> Geller 21-0065 From: INFOCNTR (PHMSA) To: Subject: Date: Attachments: Dodd, Alice (PHMSA); Hazmat Interps FW: Request for letter of interpretation - Smarter Sorting Wednesday, June 16, 2021 12:06:40 PM PHMSA request for letter of interpretation - Smarter Sorting 06152021.pdf Good afternoon Alice, Please see the attached request for a letter of interpretation. The address and phone number for the requestor is listed below. Please contact our office with any questions. Thank you, Sarah (HMIC) From: AJ Kenny Sent: Wednesday, June 16, 2021 11:55 AM To: INFOCNTR (PHMSA) Subject: Re: Request for letter of interpretation - Smarter Sorting CAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links or open attachments unless you recognize the sender and know the content is safe. Hi Sarah, Here are the details you requested: · Full Name: AJ Kenny · Physical Mailing Address: 4901 East Cesar Chavez Street, Austin, TX 78702 · Telephone Number: 206-909-2689 AJ On Wed, Jun 16, 2021 at 10:15 AM INFOCNTR (PHMSA) wrote: Dear AJ, We have received your request for a written letter of interpretation regarding the hazardous materials regulations (49 CFR Parts 171-180). The hazardous materials regulations are available at the following URL: https://www.ecfr.gov/cgi-bin/text-idx? SID=1d49a3b137cb1b6fc45251074e634b44&tpl=/ecfrbrowse/Title49/49tab_02.tpl However, before we can submit your request for processing, please respond to this email with: <<>> Full Name Physical Mailing Address Telephone Number Sincerely, Sarah, Hazardous Materials Specialist An e-mail response from this office is considered informal guidance. Formal guidance may be requested in accordance with 49 CFR 105.20. https://www.phmsa.dot.gov/standards- rulemaking/hazmat/hazardous-materials-information-center From: AJ Kenny Sent: Tuesday, June 15, 2021 11:10 PM To: Kelley, Shane (PHMSA) Cc: INFOCNTR (PHMSA) ; Charlie Vallely Subject: Request for letter of interpretation - Smarter Sorting CAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links or open attachments unless you recognize the sender and know the content is safe. Hi Shane, On June 10th and 11th I spoke with staff from the PHMSA HM Information Center regarding an exception for aqueous solutions of alcohol. Based on feedback from those calls, I am seeking a formal interpretation (see PDF attached). Please let me know if you have any questions about the request. Best regards, AJ Connect with us here: LinkedIn, Facebook, Instagram, Twitter, BuiltInAustin <<>> Connect with us here: LinkedIn, Facebook, Instagram, Twitter, BuiltInAustin <<>> Waste Repurposing International, Inc., dba 4901 E. Cesar Chavez | Austin, TX 78702 June 15, 2021 VIA E-MAIL (shane.kelley@dot.gov) Mr. Shane Kelley Director, Standards and Rulemaking Division U.S. DOT/PHMSA (PHH-10) 1200 New Jersey Avenue, SE East Building, 2nd Floor Washington, DC 20590 cc: infocntr@dot.gov - Dear Mr. Kelley, Smarter Sorting would like to request a formal letter of interpretation regarding the regulatory exception in §173.150(e)(1). Specifically, is the intent of the exception to include all alcohols in the 24% threshold, or is the intent to only include flammable alcohols in the 24% threshold? In a letter of interpretation from 2013 (13-0130), PHMSA stated that there is no regulatory definition of alcohol, however, “it is the understanding of this Office that this term is generally defined in chemical dictionaries and texts to mean any organic compound that has a hydroxyl group (-OH) bound to a carbon atom, which in turn is bound to other hydrogen and/or carbon atoms.” Although a strict reading of the chemical definition and this regulatory exception suggests all alcohols must be included in the 24% threshold, it seems plausible that the intent is to consider only flammable alcohols since they fall within the definition of a hazardous material. Consider the following example product that makes the point. • Product is a solution with a flashpoint of 54 oC and thus is flammable (i.e., Class 3) o 20% of the product is isopropanol. Isopropanol meets the definition of alcohol per the above mentioned letter of interpretation (2013 (13-0130)) and has a flashpoint of ~12 oC (below the 60 oC cutoff for “flammability”) o 20% of the product is glycerol. Glycerol is also an alcohol per the definition but has a flashpoint of ~175o C and thus this ingredient would NOT be considered flammable • None of the other ingredients in the solution would be considered a hazardous material (i.e., none of the ingredients are Marine Pollutants or otherwise regulated for transport) For reasons of the §173.150(e)(1) exception, does this product contain 20% alcohols or 40% alcohols? Should glycerol and other “non-flammable alcohols” be counted toward the 24% cutoff? Perhaps a better question: does this example product meet the requirements for §173.150(e)(1)? <<>> Waste Repurposing International, Inc., dba 4901 E. Cesar Chavez | Austin, TX 78702 49 CFR §173.150(e)(1) (e) Aqueous solutions of alcohol. An aqueous solution containing 24 percent or less alcohol by volume and no other hazardous material— (1) May be reclassed as a combustible liquid. - Respectfully submitted, AJ Kenny Director of Regulations Smarter Sorting ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `35ebaf23badb78257399a9e44dbcd00c8aadc1630ebdec09f5891bff07c4daa2` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-23T03:26:38.027Z - Document slug: `phmsa-interpretation-21-0065` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Smarter Sorting" ], "individuals": [ "AJ Kenny" ], "refIds": [ "21-0065" ], "catalogDates": [ "2021-09-23" ], "catalogParts": [ 173 ], "catalogRowCount": 2, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/72946" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "173.120", "173.120(a)", "173.150", "173.150(e)(1)" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/173120", "https://www.phmsa.dot.gov/regulations/title49/section/173150" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/75926/210065.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/75926/210065.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/75926/210065.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/21-0065-6d06e48ce6.pdf", "pdfArtifactSha256": "75e48eb8206081b28f41f2e2629c58e93f92d75e09624fac50b610cacdf0bf22", "extractedTextPath": "data/sources/phmsa-interpretations/21-0065-6d06e48ce6.v2.txt", "extractedTextSha256": "6d33bf80a2ab2d019879e8576145be4d349e03174815053a344f7e225df64336", "pageCount": 7, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```