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Section §173.304: Filling of cylinders with liquefied compressed gases

Below are the available interpretations and guidance for the given section. To return to the list of parts, use the Parts link above. If you do not see any guidance or interpretation information below, that means there is none available for the given part/section. Return to the search page to browse additional regulations sections.

PHMSA has published several Frequently Asked Questions (FAQ) documents on regulatory topics. Please review our FAQ documents below:

Additionally PHMSA has Hazardous Materials FAQs based on letters of interpretation on the following topics:

This section of the website provides the ability to find regulations information including regulations parts, content of sections, and interpretations for regulations sections. Below is a list of parts, identified by the part number and subject. To browse sections by part, click on the subject link below. You will be taken to the eCFR website to view sections for a part.

A written regulatory interpretation, response to a question, or an opinion concerning a pipeline safety issue may be obtained by submitting a written request to the Office of Pipeline Safety (PHP–30), PHMSA, U.S. Department of Transportation, 1200 New Jersey Avenue SE., Washington, DC 20590–0001 or at the email address: In addition to email address, the requestor must include his or her return address and should also include a daytime telephone number. Requests should be submitted at least 120 days before the time the requestor needs a response.

Note: electronic submission is provided as alternative to the 49 CFR Part 190.11(b) mail-in requirement.

The regulations text of the section can be found on the eCFR website. To view the regulations text, use the link below. For assistance, please send an email to

View section 173.304 on the ECFR website

Interpretation Responses

Ref ID Date Company Name Individual Name Response Document
21-0030 Wellmatics Joshua Howk View
14-0123 Guerrilla Air/ Tiberius Arms Mr. Gio Islas View
15-0022 Mihama Corporation MS. Andrea Kornbluth View
12-0038 Mr. Charles E. Tudor View
00-0261 Extengine Transport Systems Mr. Phillip Roberts View
02-0313 K. W. Ritchey View
98-0600 Regulatory Compliance Services Mr. R. J. Reynolds View
16-0196 PonyPak Mr. William Messner View
14-0169 A.S. Trust & Holdings, Inc. Mr. Richard Maruya View
15-0231 A.S. Trust & Holdings Mr. Richard Maruya View
11-0062 DuPont Company Mr. Randolph Martin View
08-0288 Kaplan Kirsch & Rockwell LLP Mr. Charles A. Spitulnik View
11-0274R Department of the Army Ms. Sarah Gedrich View