PURPOSE: To obtain a highly precise bath level sensor of furnace by attaching the upper part of a ceramic tube at the upper part of a furnace shell, connecting said part to a switch type pressure detector through a heat radiating part, radiating at the heat radiating part the air pressure corresponding to the bath level in the ceramic tube dipped in a molten metal, then detecting said pressure by the pressure detector.
CONSTITUTION: In case the invention is applied to Al holding furnace, the Al molten metal 1 is fed in a furnace vessel 3, and heated by an under heater H. The bath level sensor 7 has the ceramic tube 7a, the heat radiating part 7b connected to the upper part, the switch type pressure detector 7c fixed to the part 7b. In this case, the upper part of the tube 7a is fixed to the upper part of the furnace shell 4 through a fixing member 13, and the lower end of the part 7b is fixed to the inside upper part of the member 13 through a bushing 15. The input side of the detector 7c is fixed to the upper end of the part 7b, when an inner space 16 of the tube 7a becomes a prescribed pressure, the detector 7c detects said phenomenon, and the switch is operated. Namely, when the bath level in furnace becomes a prescribed position, the detector 7c is operated.
KATOU MASARU
IKEDA TADAO
YANAKA MASATOSHI
TOSHIBA DENKOU KK