FLUE

flue. Flue, n. soft down or fur, the pipe of a chimney

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Flue (?), n. [[Cf. OF. flue a flowing, fr. fluer to flow, fr. L. fluere (cf. Fluent); a perh. a corruption of E. flute.]] An inclosed passage way for establishing and directing a current of air, gases, etc.; an air passage; esp.: (a) A compartment or division of a chimney for conveying flame and smoke to the outer air. (b) A passage way for conducting a current of fresh, foul, or heated air from one place to another. (c) (Steam Boiler) A pipe or passage for conveying flame and hot gases through surrounding water in a boiler; — distinguished from a tube which holds water and is surrounded by fire. Small flues are called fire tubes or simply tubes. Flue boiler. See under Boiler. — Flue bridge, the separating low wall between the flues and the laboratory of a reverberatory furnace. — Flue plate (Steam Boiler), a plate to which the ends of the flues are fastened; — called also flue sheet, tube sheet, and tube plate. — Flue surface (Steam Boiler), the aggregate surface of flues exposed to flame or the hot gases.