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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #23-0068

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: UL Solutions

Individual Name: Kevin Skerrett

Location State: NY Country: US

View the Interpretation Document

Response text:

October 16, 2023

Kevin Skerrett
Senior Regulatory Specialist
UL Solutions
77 Clearbrook Drive
Rochester, NY  14609

Reference No. 23-0068

Dear Mr. Skerrett:

This letter is in response to your July 21, 2023, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to shipping a gaseous hazardous material in a cartridge that also contains a small amount of liquid content and whether to classify and describe it as "UN2037, Receptacles, small, containing gas or gas cartridges (non-flammable) without release device, not refillable and not exceeding 1 L capacity, 2.2" or as "UN3500, Chemical under pressure, n.o.s., 2.2." Specifically, you describe a cartridge of 1 fluid oz. capacity with 1% of content being a non-regulated irritant liquid while the remainder of the cartridge is filled with a Division 2.2 gas you term a propellant. You state that the cartridge is intended to be installed in a separate device which—when activated—emits the gas along with the small amount of the non-regulated irritant liquid. Your concerns are twofold—i.e., whether this material is appropriately classified and described when using "UN2037" and whether downstream users can reship by any mode of transportation and internationally as "UN2037."

We have paraphrased and answered your questions as follows:

Q1. You ask whether it is acceptable to classify and describe this hazardous material in a cartridge as "UN2037" or is it more appropriately classified and described as “UN3500.” Further, if it is more appropriate to use "UN3500," is classifying and describing the material as "UN2037" considered a violation of the HMR.

A1. In accordance with § 173.22 of the HMR, it is the shipper's responsibility to properly classify and describe a hazardous material as this Office does not perform that function. However, it is the opinion of this Office that based on the information you have provided, we agree that the appropriate classification and description would be "UN2037" if the cartridge does not contain a release device and the material in the cartridge is not an aerosol as defined in § 171.8.

Q2. You ask whether your understanding is correct that there are no provisions that allow for "UN3500" material to be contained in a non-specification packaging and that there is no small quantity relief provision for "UN3500" material from the HMR.

A2. Your understanding is correct. There are no exceptions assigned to "UN3500" in the Hazardous Materials Table (HMT) in § 172.101 that are comparable to the exceptions provided in § 173.306 and assigned to other gas entries in the HMT. Additionally, there are no provisions for "UN3500" that would allow the use of a non-specification packaging.

Q3. You ask if the cartridge cannot be classified and described as "UN2037" and if classifying it as "UN3500" does not allow for the use of a non-specification packaging, would a person need to apply for a special permit to ship the cartridge and its contents.

A3. See answer A1.

Please note that a downstream user who receives a package containing "UN2037" may reship this material domestically and internationally provided a person reships the material in accordance with the conditions found in the HMT.

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


Dirk Der Kinderen
Chief, Standards Development Branch
Standards and Rulemaking Division

171.8, 172.101, 173.22, 173.306

Regulation Sections

Section Subject
171.8 Definitions and abbreviations
172.101 Purpose and use of hazardous materials table
173.22 Shipper's responsibility
173.306 Limited quantities of compressed gases