Gas meters with switches containing mercury
Pipeline and Hazardous Materials Safety Administration · Oct 1, 2007 · Reference No. 07-0176
Interprets: 49 CFR § 173.164
Reggie’s quick take
A company that ships gas meters asked whether meters with small mercury switches are covered by the Hazardous Materials Regulations when shipped under § 173.164(c)(2). The agency said they are not. Under that section, switches containing no more than 15 g of mercury are excepted from the rules if they are built into a machine or apparatus and fitted so that impact damage leading to a mercury leak is unlikely in normal transport. Each switch in this case held 1.16 g, so the meters are not covered. The agency also said "subchapter" means the Hazardous Materials Regulations, 49 CFR Parts 171-180.
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 August 29, 2007 letter requesting clarification of requirements for transport of manufactured articles containing mercury under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you ask whether gas meters with switches containing mercury transported in accordance with § 173.164(c)(2) are subject to the HMR. Additionally, you request a definition of "subchapter" as it pertains to § 173.164(c)(2).
You state that your company transports gas meters with an electronic device containing a small mercury switch attached to each gas meter. You also state each switch contains 1.16 g (0.04 ounces) of mercury.
Based on the information provided, the gas meters would not be subject to the requirements of the HMR. In accordance with § 173.164(c)(2), "thermometers, switches and relays, each containing a total quantity of not more than 15 g (0.53 ounces) of mercury, are excepted from the requirements of the subchapter if installed as an integral part of a machine or apparatus and so fitted that shock of impact damage, leading to leakage of mercury, is unlikely to occur under conditions normally incident to transport."
Regarding the definition of "subchapter" as it pertains to § 173.164(c)(2), "subchapter" refers to the regulations contained in Title 49, Subtitle B, Chapter I, Subchapter C, Parts 171-180 of the Code of Federal Regulations (CFR), more commonly referred to as the Hazardous Materials Regulations (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.