External combustion

External combustion means fired combustion in which the flame and products of combustion are separated from contact with the process fluid to which the energy is delivered. Process fluids may be air, hot water, or hydrocarbons. External combustion equipment may include fired heaters, industrial boilers, and commercial and domestic combustion units.

Source

40 CFR § 98.238

Scoping language

Except as provided in this section, all terms used in this subpart have the same meaning given in the Clean Air Act and subpart A of this part.