As used in this subpart, all terms not defined herein shall have the meaning given them in the Act and in subpart A of this part.

(a) Portland cement plant means any facility manufacturing portland cement by either the wet or dry process.

(b) Bypass means any system that prevents all or a portion of the kiln or clinker cooler exhaust gases from entering the main control device and ducts the gases through a separate control device. This does not include emergency systems designed to duct exhaust gases directly to the atmosphere in the event of a malfunction of any control device controlling kiln or clinker cooler emissions.

(c) Bypass stack means the stack that vents exhaust gases to the atmosphere from the bypass control device.

(d) Monovent means an exhaust configuration of a building or emission control device (e.g., positive-pressure fabric filter) that extends the length of the structure and has a width very small in relation to its length (i.e., length to width ratio is typically greater than 5:1). The exhaust may be an open vent with or without a roof, louvered vents, or a combination of such features.