### Question
How is the term refrigerant defined?


### Answer
The term **refrigerant** is defined in *42 U.S.C. § 7671d* as the following:

> any class II substance used for heat transfer in a refrigerating system

#### Citation:
  - *42 U.S.C. § 7671d*
  - Heading: **CHAPTER 83-ENERGY EXTENSION SERVICE > SUBCHAPTER VI-STRATOSPHERIC OZONE PROTECTION**

