Okla. Admin. Code § 252:100-35-1.1
The following words and terms, when used in this Subchapter, shall have the following meaning, unless the context clearly indicates otherwise:
"Basic oxygen furnace" means a furnace in which the melting and refining of iron are accomplished by the addition at high velocities of large amounts of high purity oxygen to the atmosphere above the surface of the metal bath. The metal is held in a tiltable vessel with a basic refractory lining. Such a furnace includes the furnace proper, oxygen lance, scrap and flux charging units, iron transfer units, gas collecting and cleaning equipment, stacks and any other auxiliaries pertinent to the process.
"Blast furnace" means furnace and equipment used in connection with the smelting process of reducing metallic ores to molten metal in which primarily oxygen is removed from the ore and gas is produced as a by-product. The furnace and equipment consists of, but is not limited to, the furnace proper, charging equipment, stoves, bleeders, gas dust-cleaning devices, after-burner, and other auxiliaries pertinent to the process.
"Existing source" means any gray iron cupola, blast furnace, basic oxygen furnace, petroleum catalytic cracking unit or petroleum catalytic reforming unit, in being on July 1, 1972, and not modified thereafter so as to increase the emission of carbon monoxide.
"Gray iron cupola" means shaft-type furnace used for the melting of metals usually consisting of, but not limited to, the furnace proper, tuyeres, fans or blowers, tapping spout, charging equipment, gas-cleaning devices and other auxiliaries. Shaft furnaces used for processing non-metallic materials are not included under this definition but are included in the definition of process equipment.
"New source" means any gray iron cupola, blast furnace, basic oxygen furnace, petroleum catalytic cracking unit or petroleum catalytic reforming unit, in being after July 1, 1972.
Okla. Admin. Code § 252:100-35-1.1