Steiner Tunnel 1 : (Amer. term) A rectangular duct 457. 2 mm (18 in. by 305 mm (12 in. used to determine the flame spread ratings of structural materials, 7. 62 m (25 ft) long samples are used
H. J. Porter (Chairman - Technical Committee), Dictionary of Fire Technology, The Institution of Fire Engineers, The Victory Press (Leicester) Ltd. 1979 UK. (Fr Tech - Brit) {81}