Carbon dioxide

Carbon dioxide means a colorless, odorless, electrically nonconductive inert gas (chemical formula CO2) that is a medium for extinguishing fires by reducing the concentration of oxygen or fuel vapor in the air to the point where conbustion is impossible.

Source

29 CFR § 1910.155

Scoping language

Scope. This subpart contains requirements for fire brigades, and all portable and fixed fire suppression equipment, fire detection systems, and fire or employee alarm systems installed to meet the fire protection requirements of 29 CFR part 1910.