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Interpretation Response #19-0066

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

Interpretation Response Details

Response Publish Date:

Company Name: Cryogenic Services, Ltd.

Individual Name: Connor Orban

Location State: OH Country: US

View the Interpretation Document

Response text:

September 20, 2019

Connor Orban
Cryogenic Services, Ltd.
P.O. Box 417
Hartville, OH 44632

Reference No. 19-0066

Dear Mr. Orban:

This letter is in response to your May 24, 2019, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to cryogenic liquids. You state that you transport multiple 180 L cylinders at 22 psig by highway. Specifically, you ask for clarification regarding the use of the exceptions for cryogenic liquids as provided in § 173.320.

We have paraphrased and answered your questions as follows:

Q1. You ask whether there is a size limitation on packagings that qualify for the exceptions provided in § 173.320.

A1. The answer is no. The exception for cryogenic liquids does not limit the size of the packaging; however, it does limit the type of packaging to Dewar flasks, insulated cylinders, insulated portable tanks, insulated cargo tanks, and insulated tank cars that are designed and constructed so that the pressure will not exceed 25.3 psig under ambient conditions.

Q2. When using the cryogenic liquids exceptions, you ask whether you are required to placard the motor vehicle when transporting a Dewar flask or cylinder at 22 psig or less.

A2. The answer is no, unless you are transporting refrigerated liquid oxygen (i.e., UN1073, Oxygen, refrigerated liquid (cryogenic liquid). Liquid oxygen is not excepted from placarding by § 173.320, if applicable (e.g., > 1000 lbs gross weight of non-bulk cylinders on a transport vehicle).

Q3. You ask whether you are subject to the registration requirements in § 107.601.

A3. If subject to placarding (e.g., liquid oxygen in non-bulk cylinders exceeding 1000 lbs gross weight), the answer is yes. See § 107.601(a)(6). Otherwise, the answer is no.

Q4. You ask whether § 173.320 specifies how these packages should be secured inside the vehicle.

A4. The answer is no. While § 173.320 provides relief from the specific loading and unloading requirements prescribed in § 177.834, you are still required to comply with the Federal Motor Carrier Safety Administration's regulations (FMCSR), which have requirements that address protection against shifting or falling cargo (see FMCSR; 49 CFR Part 393 Subpart I - Protection Against Shifting and Falling Cargo).

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

173.320, 107.601, 107.601(a)(6), 177.834

Regulation Sections

Section Subject
107.601 Applicability
173.320 Cryogenic liquids; exceptions
177.834 General requirements