40 CFR § 98.208 - Definitions.

---
identifier: "/us/cfr/t40/s98.208"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 98.208 - Definitions."
title_number: 40
title_name: "Protection of Environment"
section_number: "98.208"
section_name: "Definitions."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "98"
part_name: "MANDATORY GREENHOUSE GAS REPORTING"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401-7671q."
regulatory_source: "74 FR 56374, Oct. 30, 2009, unless otherwise noted."
cfr_part: "98"
---


# 98.208 Definitions.

All terms used in this subpart have the same meaning given in the Clean Air Act and subpart A of this part. Additionally, some sector-specific definitions are provided below:

*Carrier gas* means the gas with which cover gas is mixed to transport and dilute the cover gas thus maximizing its efficient use. Carrier gases typically include CO<sub>2</sub>, N<sub>2</sub>, and/or dry air.

*Cover gas* means SF<sub>6</sub>, HFC-134a, fluorinated ketone (FK 5-1-12) or other gas used to protect the surface of molten magnesium from rapid oxidation and burning in the presence of air. The molten magnesium may be the surface of a casting or ingot production operation or the surface of a crucible of molten magnesium that feeds a casting operation.