Dual Labeling Cylinders "PIH" and "TOXIC GAS"
Pipeline and Hazardous Materials Safety Administration · Dec 22, 1999 · Reference No. 99-0076
Interprets: 49 CFR § 172.401
Reggie’s quick take
A company asked whether a cylinder of sulfuryl fluoride (UN2191, Division 2.3) may carry both the old POISON GAS or TOXIC GAS label and the new PIH label. PHMSA said yes, dual display is acceptable. The old label reflects the hazard under the IMDG Code, which the HMR allows under § 172.401(a)(2) and (c). The old label may be used until October 1, 2001, but only if the package is marked "inhalation hazard" under § 172.313(a), the package is shipped in a closed vehicle or freight container marked with the PIH identification number under § 172.313(c), and that container is placarded under subpart F of part 172.
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 is in response to your inquiry concerning whether the use of two different primary hazard labels for the same hazard class is permissible under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you inquire whether a POISON GAS or TOXIC GAS label and the new poison inhalation hazard (PIH) label may be displayed on a cylinder containing Sulfuryl fluoride, 2.3, UN2191. The International Maritime Dangerous Goods Code does not provide for the display of the PIH label as required by the HMR effective October 1, 1999.
The answer to your question is yes, the dual display of the old POISON GAS or TOXIC GAS label and the new PIH label is acceptable. The old label represents the hazard of material in the package and is required under the International Maritime Dangerous Goods (IMDG) Code. Its continued use under the HMR is acceptable as specified in § 172.401(a)(2) and (c) respectively.
In a recent interim final rule (September 16, 1999; HM-206D; 64 FR 50260), we provided a transition period until October 1, 2001, to allow a package containing a PIH material to be labeled with the old POISON GAS or TOXIC GAS label in accordance with the IMDG Code, subject to the following conditions and limitations:
(1) The material must be packaged in accordance with the HMR;
(2) The package must be marked "inhalation hazard" in accordance with § 172.313(a);
(3) The package must be transported in a closed transport vehicle or freight container that is marked with the identification number for any quantity of PIH materials as prescribed in § 172.313(c);
(4) If a closed transport vehicle or freight container contains more than one PIH material, it must be marked with the identification number determined according to § 172.313(c)(3); and
(5) A closed transport vehicle or freight container must be placarded as required by subpart F of part 172 of the HMR.
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.