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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 #12-0016

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

Interpretation Response Details

Response Publish Date:

Company Name:

Individual Name:

Location State: CA Country: US

View the Interpretation Document

Response text:

April 5, 2012


Mr. David R. Bacca
DaRuBa Enterprises
PO Box 52858
Riverside, CA 92517-3858

Ref. No. 12-0016

Dear Mr. Bacca:

This responds to your January 17, 2012 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the requalification and use of Department of Transportation (DOT) 4B, 4B240ET and special permit (SP) cylinders. Your questions are paraphrased and answered as follows:

Q1. Are DOT 4B cylinders manufactured in accordance with DOT-SP 9837 authorized for the transport of hazardous materials?

A1. No. DOT-SP 9837, which authorized the manufacture, mark, sale, and use of DOT 4B cylinders marked with the lot number instead of the serial number, expired on November 30, 2009. No person may use DOT-SP 9837 when the special permit has expired or is otherwise no longer in effect. An individual who wishes to fill and offer a DOT 4B cylinder under the terms of DOT SP-9837 may request the Associate Administrator reissue the special permit with modifications to authorize the continued transportation in commerce of the cylinder.

Q2. Are DOT 4B240ET cylinders that are not marked with the service pressure "240" following the specification authorized by the HMR?

A2. Yes. In the case of a DOT 4B240ET cylinder, 240 psig is the only authorized service pressure. Since the service pressure is part of the specification marking, there is no need to add an additional mark to denote the service pressure.

Q3. The size requirements for DOT 4B240ET cylinders outlined in § 178.55(a), state that the maximum outside diameter is five inches. Are cylinders with an outside diameter less than five inches authorized?

A3. Yes. This provision limits the maximum outside diameter of the cylinder to five inches. The requirement is not intended to imply that the outside diameter of the cylinder must be exactly five inches.

I hope this information is helpful. If you have further questions, please contact this office.



Ben Supko
Acting Chief, Standards Development
Standards and Rulemaking Division

178.55(a), 180.205, 173.309

Regulation Sections

Section Subject
173.309 Fire extinguishers
178.55 Specification 4B240ET welded or brazed cylinders