F MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F27 FURNACES; KILNS; OVENS; RETORTS
F27B FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
F27B5/00 Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
F27B5/06 Details, accessories, or equipment peculiar to furnaces of these types
F27B5/16 Arrangements of air or gas supply devices