Md. Code, Pub. Safety § 12-706

(a) In this section, “appliance” means any device that: (1) contains and uses a class I or class II substance or a substitute for a class I or class II substance, as defined in 42 U.S.C. 7671a, as a refrigerant; and (2) is used for a household or commercial purpose, including an air conditioner, a refrigerator, a chiller, or a freezer. (b) Notwithstanding any other provision of law, except for regulations issued by the Department of the Environment, no provision of the State building code or other law or regulation may prohibit or otherwise limit the use of a refrigerant if: (1) the refrigerant is designated as acceptable for use in accordance with 42 U.S.C. 7671k; and (2) any appliance containing the refrigerant designated for acceptable use is installed and used in accordance with the safety standards and use conditions under 42 U.S.C. 7671k.