# FHP Manufacturing — Hazardous Materials Safety Interpretation **Citation:** 24-0057 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2024-10-24 24-0057 response to FHP Manufacturing concerning 173.307. ## Document text <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, DC 20590 October 24, 2024 Mr. Scott D. Langston General Manager FHP Manufacturing 601 N.W. 65th Court Fort Lauderdale, FL 33309 Reference No. 24-0057 Dear Mr. Langston: This letter is in response to your June 10, 2024, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to transporting refrigerating machines. Specifically, you ask whether an appliance containing two separate (i.e., isolated) refrigerant circuits, each containing up to 12 kg (25 pounds) or less of a flammable, non-toxic gas, qualifies for the exception for compressed gases in refrigerating machines provided in § 173.307(a)(4)(iii). The answer is yes, provided the refrigerating machine is not transported by air. Refrigerating machines and components thereof, containing 12 kg (25 pounds) or less of a flammable, non- toxic gas, are not subject to the requirements of the HMR, unless transported by air. It is the opinion of this Office that this exception continues to apply to separate—and isolated— refrigerating machines regardless of whether the refrigerating machines component parts make up a larger instrument or piece of equipment. The isolated refrigerant circuits may not utilize the same tubing, piping, or relevant components to function. I hope this information is helpful. Please contact us if we can be of further assistance. Sincerely, Alexander Wolcott Acting Chief, Regulatory Review and Reinvention Branch Standards and Rulemaking Division <<>> Pollack 24-0057 From: INFOCNTR (PHMSA) To: Hazmat Interps Subject: FW: Request for Letter of Interpretation regarding 49 CFR § 173.307(a)(4)(iii) Date: Friday, June 14, 2024 1:57:31 PM Hello, Please see below request for letter of interpretation. Thanks, Jonathon From: Langston Scott (HCFH/GM FldP/PM FldP/TEF) Sent: Monday, June 10, 2024 3:38 PM To: INFOCNTR (PHMSA) Subject: RE: Request for Letter of Interpretation regarding 49 CFR § 173.307(a)(4)(iii) 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. Hello, Please note the reference in email below pertains to 40 CFR § 82.152: Code of Federal Regulations § 82.152 Definitions: Appliance, including any air conditioner, states: For a system with multiple circuits, each independent circuit is considered a separate appliance. Best regards, Scott D. Langston General Manager FHP Manufacturing | 601 N.W. 65th Court | Fort Lauderdale, FL 33309 | USA | Tel. +1(954)513-3600 | Mobile +1(816)604-0912 | Scott.Langston@us.bosch.com From: Langston Scott (HCFH/GM FldP/PM FldP/TEF) Sent: Tuesday, April 9, 2024 7:50 AM To: pipeline_interp_submittal@dot.gov Subject: Request for Letter of Interpretation regarding 49 CFR § 173.307(a)(4)(iii) Dear Mr. Schoonover, Prior to using party status to special permits (SP) 21287 and 21379, I would like to have clarified § 173.307(a)(4)(iii) exception regarding “air conditioners, and components thereof, such as precharged tubing containing”, and if it includes independent circuits. <<>> Code of Federal Regulations § 82.152 Definitions: Appliance, including any air conditioner, states: For a system with multiple circuits, each independent circuit is considered a separate appliance. ANSI/ASHRAE Standard 15-2022 Definitions: independent circuit: a closed refrigeration circuit that is arranged in such a manner that, in the event of a single point of failure, the release of refrigerant is limited to only the quantity contained within the refrigeration circuit. system refrigerant charge (mc): the total mass of refrigerant in an independent circuit of a system, including both factory and field refrigerant charge. self-contained system: a complete, factory-assembled and factory-tested system that is shipped in one or more sections and has no refrigerant-containing parts that are joined in the field by other than companion valves or block valves. If multiple independent factory charged and tested circuits each contain 12 kg (25 pounds) or less of a flammable, non-toxic gas, within one self-contained system, is 49 CFR § 173.307(a)(4)(iii) exception applicable? Best regards, Scott D. Langston General Manager FHP Manufacturing | 601 N.W. 65th Court | Fort Lauderdale, FL 33309 | USA | Tel. +1(954)513-3600 | Mobile +1(816)604-0912 | Scott.Langston@us.bosch.com ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `3cbf90f6879461926f1b6b81dfb4da96cacce0a3ae88b85de9485fbb7c2108a7` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-23T07:49:08.265Z - Document slug: `phmsa-interpretation-24-0057` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "FHP Manufacturing" ], "individuals": [ "Mr. Scott D. 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