PHMSA letter of interpretation

Pressure Proof Test Preformed on Certain DOT-4 Series Cylinders

Pipeline and Hazardous Materials Safety Administration · May 24, 2006 · Reference No. 05-0239

PHMSA says to use caution with this letter. On January 21st, 2016, PHMSA published Final Rule, HM-233F, which incorporated Special Permit 12084 by revising § 180.209(e) to change the applicability of the proof pressure test.

Interprets: 49 CFR § 180.209

Reggie’s quick take

Someone asked PHMSA to reconsider an earlier interpretation about whether the proof pressure test in § 180.209(e) can be used on certain DOT-4 series cylinders that hold refrigerant gas from recovery. The asker worried that these cylinders could carry unknown contamination. PHMSA's answer is that it is the shipper's job to decide whether a refrigerant recovery cylinder is "commercially free from corroding components." If it is, the alternative test in § 180.209(e) may be used. The rules do not ban this testing, and PHMSA found no exception for the situation described. To change the rules, a person may petition for rulemaking under §§ 106.95 and 106.100.

Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.

This responds to your letter requesting reconsideration of a previous interpretation (Ref. No. 03-0164) sent to you regarding whether the proof pressure test prescribed in § 180.209(e) may be performed on certain DOT-4 series cylinders used for refrigerant gas recovery.

Because of the possibility that these cylinders are subject to unknown contamination during the recovery process, you disagree with us that the proof pressure test, authorized as an alternative, is acceptable to be performed on DOT-4 series cylinders used as refrigerant gas recovery cylinders.

Although industry practice appears to take the position that all refrigerant gas recovery systems are contaminated, we believe it is the shipper's responsibility to determine if a refrigerant gas cylinder is "commercially free from corroding components", and thus can take advantage of the alternative testing authorized in § 180.209(e). There is nothing in the HMR prohibiting such testing, and there is no exception in the HMR to this practice under the circumstances you described.

If you wish to add, amend or delete a regulation, you may petition for rulemaking under the requirements in § 106.95 and 106.100.

A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.