# Sensors, Inc. — Hazardous Materials Safety Interpretation **Citation:** 23-0033 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2023-05-08 23-0033 response to Sensors, Inc. concerning 171.1. ## Document text <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, DC 20590 May 8, 2023 Mr. Doug Heisler Manager, Quality and Service Sensors, Inc. 6812 State Rd. Saline, MI 48176 Reference No. 23-0033 Dear Mr. Heisler: This letter is in response to your March 27, 2023, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) regarding the applicability of the HMR to a Portable Emission Measurement System, which contains DOT specification cylinders that release a controlled amount of certain Division 2.1 and 2.2 materials without removing the cylinders from the vehicle on which they are transported. Specifically, you state that you install these systems on your customers’ vehicles a few times per year to record emissions measurements and that these systems utilize a fuel bottle during this measurement while your customers operate their vehicles. You further state that your company currently possesses a Special Permit (Ref. No. 15839) that authorizes the transportation of these systems and the controlled release of certain Division 2.1 and 2.2 materials. You ask whether this activity is subject to the HMR and therefore, whether you need to renew your special permit. Based on the information you have provided, the answer is no. Section 171.1(b) and (c) state that the requirements of the HMR apply to each person who offers a hazardous material for transportation in commerce or transports a hazardous material in commerce. It is the opinion of this Office that auxiliary equipment attached to a motor vehicle with the intent of measuring vehicle emissions is not considered to be “in commerce.” Therefore, the requirements of the HMR are not applicable to your device. <<>> However, please be aware that there may be applicable requirements from other Federal agencies such as the Federal Motor Carrier Safety Administration (FMCSA), who can be reached at 1-800-832-5660, the National Highway Traffic Safety Administration (NHTSA), who can be reached at 1-888-327-4236, and the Environmental Protection Agency (EPA), who can be reached at 1-734-214-4333. I hope this information is helpful. Please contact us if we can be of further assistance. Sincerely, T. Glenn Foster Chief, Regulatory Review and Reinvention Branch Standards and Rulemaking Division <<>> Larson 23-0033 From: INFOCNTR (PHMSA) To: Dodd, Alice (PHMSA) Cc: Hazmat Interps Subject: FW: Request for Interpretation of the applicability of the HMR Date: Monday, April 3, 2023 4:28:40 PM Hi Alice, Below is the address for the interpretation request for Doug Heisler. Please let me know if you need anything else from us. Regards, -Breanna From: Doug Heisler Sent: Monday, April 3, 2023 3:55 PM To: INFOCNTR (PHMSA) Subject: RE: Request for Interpretation of the applicability of the HMR 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 Breanna, Thank you for your acknowledgement. Our physical address is: Sensors, inc. 6812 State Rd. Saline, MI 48176 From: INFOCNTR (PHMSA) Sent: Monday, April 3, 2023 3:28 PM To: Doug Heisler Subject: RE: Request for Interpretation of the applicability of the HMR Dear Doug, 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: Physical Mailing Address Sincerely, Breanna, 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: Doug Heisler Sent: Monday, March 27, 2023 8:03 AM To: INFOCNTR (PHMSA) Cc: Joe Morrill Subject: Request for Interpretation of the applicability of the HMR 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. To whom it may concern, Sensors, Inc. is currently in possession of a Special Permit (SP-15839) that “..authorizes the transportation in commerce of certain DOT specification cylinders as part of a Portable Emission Measurement System, which release a controlled amount of certain Division 2.1 and 2.2 materials without removing the cylinder from the vehicle on which it is transported.” Our special permit is coming due for renewal, but we would like to request an interpretation of the HMR as we are not certain it applies to our activity and therefore might not be required to maintain. We are unsure how to interpret the need for a permit. We are not a carrier and we do not haul goods for sale/resale. We do not sell, deliver, or distribute any gases, either. What we do is work with our customers a few times (<10) per year to install our equipment on their vehicle(s) in order to record emissions measurements per (EPA 1065…); and that equipment utilizes <<>> a fuel bottle during the emission measurement while our customer uses/operates their vehicle. These measurements are less than a typical driving day for the customer, and usually only a few hours. May we ask you to please consider and address the following 3 questions: Question #1: Given our specific and narrow activity, is this use subject to HMR or require this permit? If ‘Yes’ to question #1: Question #2: Is 49 CFR 177.834(h) applicable to our activity? If neither question #1 or question #2 are applicable: Question #3: Do we need to apply for ‘any’ Special Permit? Please let me know if you require further details or information. Thank you for your time. With regards, Doug Doug Heisler | Sensors, Inc. | Manager, Quality and Service | +1.734.295.9483 (o) | www.sensors-inc.com Sensors – 50 years of innovation built on experience Disclaimer: This email and any attachments may contain confidential and privileged information. If you are not the intended recipient, please notify the sender immediately by return email, delete this e-mail and destroy any copies. Any dissemination or use of this information by a person other than the intended recipient is unauthorized and may be illegal. ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `c6755820cca4019c149e0811c6b549a0615fc1816390a22beca0e9e715f2eb3b` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T03:43:18.705Z - Document slug: `phmsa-interpretation-23-0033` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Sensors, Inc." ], "individuals": [ "Mr. Doug Heisler" ], "refIds": [ "23-0033" ], "catalogDates": [ "2023-05-08" ], "catalogParts": [ 171 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/73691" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "171.1", "171.1(b)", "177.834(h)" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/1711" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/77571/230033.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/77571/230033.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/standards-rulemaking/hazmat/interpretations/77571/230033.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/23-0033-504038d1c5.pdf", "pdfArtifactSha256": "ae2a705bd6fdfac0e70e4090246feab66c1f42d1cd56c34bd5548240ebeea577", "extractedTextPath": "data/sources/phmsa-interpretations/23-0033-504038d1c5.v2.txt", "extractedTextSha256": "39b2584f576bdbbcd1fbd7cbf2e1be7ac7aaefc06e01048ba7de2d46014f06df", "pageCount": 5, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```