Refrigeration Machine Regulated by Highway

October 13, 2022

Reference No. 22-0010

This letter is in response to your February 18, 2022, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to a refrigeration device. In your email, you note that the device is constructed with four gas cylinders manifolded together—with each cylinder containing 50 pounds of carbon dioxide (i.e., total capacity of 200 pounds)—used to support the refrigerating function of the device. Further, you note that after use the liquid CO2 refrigerant is vented in small amounts, similar to a dry ice cooling device, and is not an asphyxiant under normal conditions. Specifically, you ask whether the refrigeration device, which is intended to be in use during ground and air transportation to maintain temperature control of products inside the device—e.g., food and pharmaceuticals—is subject to the HMR.

The answer is yes. The HMR does not permit the release of hazardous materials (CO2) during transportation, as described in your email. However, you may consider applying for a special permit for the use and transportation of these refrigeration devices by submitting an application to the Associate Administrator for Hazardous Materials Safety in conformance with the requirements prescribed in 49 CFR Part 107, Subpart B.

You may obtain information on the special permit application process from our website at https://www.phmsa.dot.gov/approvals-and-permits/hazmat/hazardous-materials-approvals-and-permits-overview, or by calling PHMSA's General Approvals and Permits Division at (202) 366-4511.

I hope this information is helpful. Please contact us if we can be of further assistance.