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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 #17-0129

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

Interpretation Response Details

Response Publish Date:

Company Name: United Brands

Individual Name: Jimmy Zahriya

Location State: CA Country: US

View the Interpretation Document

Response text:

February 5, 2018

Jimmy Zahriya
Chief Executive Officer
United Brands
170 Associated Road
South San Francisco, CA 94080

Reference No. 17-0129

Dear Mr. Zahriya:

This letter is in response to your November 27, 2017, letter and follow-up email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to pressure relief device (PRD) requirements for U.S. Department of Transportation (DOT) 2P or 2Q containers filled with butane.

We have paraphrased and answered your questions as follows:

Q1. You state that your company complies with § 173.304b for use of DOT 2P and 2Q containers for the transportation of butane.

A1. This understanding of applicability is incorrect. Section 173.304b applies to the use of UN pressure receptacles, not DOT specification packagings. DOT 2P and 2Q containers are DOT specification containers; therefore, § 173.304a applies.

Q2. You ask if DOT 2P and 2Q containers filled with liquefied butane at a pressure less than 32 psig at 70 °F and 81 psig at 130 °F must be equipped with a PRD.

A2. The answer is no. DOT 2P and 2Q containers are considered inner non-refillable metal receptacles, not cylinders; therefore, the pressure relief requirements and exceptions found in § 173.301(f) do not apply. DOT 2P and 2Q containers are authorized for liquefied petroleum gases (LPG), such as butane, under the provisions of § 173.304a(d)(3)(ii). Provided the maximum capacity of the receptacle does not exceed 31.83 cubic inches and the maximum filling pressure does not exceed 35 psig at 70 °F and 100 psig at 130 °F, no PRD is required for a DOT 2P or 2Q container filled with LPG.

Note that a DOT 2P or 2Q container filled with LPG with pressures exceeding 35 psig but not exceeding 45 psig at 70 °F and exceeding 100 psig but not exceeding 105 psig at 130 °F must have a PRD in accordance with § 173.304a(d)(3)(ii) Note 2.

Q3. You ask whether the dispensing port at the top of the DOT 2P or 2Q container, which is designed to allow the contents to flow out when actuated mechanically in the normal use of the device, is a PRD.

A3. Your incoming letter has not provided enough information about the manual dispensing port to make this determination. However, as discussed in Question Q2, a PRD is not required in the scenario you described.

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

173.304b, 173.301(f), 173.304a(d)(3)(ii)

Regulation Sections

Section Subject
173.301 General requirements for shipment of compressed gases and other hazardous materials in cylinders, UN pressure receptacles and spherical pressure vessels
173.304a Additional requirements for shipment of liquefied compressed gases in specification cylinders
173.304b Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles