# National Presto Safety — Hazardous Materials Safety Interpretation **Citation:** 20-0088 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2021-03-24 20-0088 response to National Presto Safety concerning 178.35, 180.205, 180.209. ## Document text <<>> U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Avenue, SE Washington, DC 20590 March 24, 2021 J.R. Nerat Senior Technical Director National Presto Safety 3925 North Hastings Way Eau Claire, WI 54703 Reference No. 20-0088 Dear Mr. Nerat: This is in response to your November 12, 2020, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the periodic cylinder requalification period for Department of Transportation (DOT) specification 3AL cylinders used as fire extinguishers. Your questions are paraphrased and answered below. Q1. You ask whether the requalification periods identified in Table 1 to paragraph (a) of § 180.209 are intended to establish the maximum periodic cylinder requalification intervals for DOT cylinders. A1. The testing intervals established in Table 1 to paragraph (a) of § 180.209 are the maximum time frame allowed between testing intervals for each respective cylinder specification. However, the HMR does not prevent the requalification of cylinders in more frequent intervals than required. Q2. You ask whether § 180.209 allows a fire extinguisher manufacturer to specify a shorter maximum 10-year periodic retest interval in lieu of the referenced longer 12-year periodic interval for DOT 3AL cylinders. A2. As stated in A1, the requirements in § 180.209 would not prevent cylinders from being tested on a more frequent basis than what is required by the HMR. Specifically, § 180.205(c) states that “a cylinder may be requalified at any time during or before the month and year that the requalification is due.” <<>> Q3. You ask whether the HMR permits additional markings to assist fillers in properly differentiating and identifying the applicable recommended DOT periodic cylinder requalification requirements. A3. As stated in A2, the HMR does not prevent a cylinder manufacturer from recommending shorter testing intervals for cylinders. Section 178.35(f)(6) provides that “other markings are authorized provided they are made in low stress areas other than the side wall and are not of a size and depth that will create harmful stress concentrations. Such marks may not conflict with any DOT required markings.” Therefore, markings recommending shorter requalification time frames would be permitted on a cylinder provided they are in compliance with § 178.35(f)(6). Please note that a cylinder marking recommending requalification at shorter intervals than required in § 180.209 may cause confusion and PHMSA does not recommend this practice. I hope this information is helpful. Please contact us if we can be of further assistance. Sincerely, T. Glenn Foster Chief, Regulatory Review and Reinvention Branch Standards and Rulemaking Division <<>> Andrews From: INFOCNTR (PHMSA) To: Subject: Date: Attachments: Dodd, Alice (PHMSA); Hazmat Interps FW: DOT Interpretation CFR-49 part 180.209 Friday, November 13, 2020 12:22:04 PM DOT 3AL formal interpretation request submited Nov 12, 2020.docx 20-0088 Hi Alice, Please see attached for a letter of interpretation request. Please contact our office with any questions. Thank you, Sarah (HMIC) From: J.R. Nerat [mailto:jrnerat@gopresto.com] Sent: Thursday, November 12, 2020 4:27 PM To: INFOCNTR (PHMSA) Subject: DOT Interpretation CFR-49 part 180.209 CAUTION: This email originated from outside of the Department of Transportation (DOT). Do not click on links or open attachments unless you recognize the sender and know the content is safe. November 12, 2020 Department of Transportation Pipeline and Hazard Material Safety Administration Phone: 202-366-4488 (1) Attention: Mr. Shane Kelly Subject: (CFR-49 part 180.209) Formal Request for Interpretation Dear Sir, Please see attached request. Sincerely, J.R. Nerat Senior Technical Director National Presto Safety 3925 North Hastings Way Eau Claire, WI 54703 <<>> (906) 753-3199 direct office line (906) 290-0000 cell ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `8c31302581ca97412656a541b247f90c0a97eb7b6fae479147d768913b722a96` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T19:26:01.732Z - Document slug: `phmsa-interpretation-20-0088` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "National Presto Safety" ], "individuals": [ "J.R. 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