Device and system for measuring a temperature of a molten metal

A device for measuring a temperature of a molten metal bath, the device comprising:

• (a) a cored wire having an immersion end and an opposite end, the cored wire comprising:
• (a1) an optical fiber,
• (a2) a first metal tube accommodating the optical fiber,
• (a3) a filler layer surrounding the first metal tube, and
• (a4) a second metal tube accommodating the filler layer, and
• (b) a detector to receive a signal transmitted by the optical fiber, the detector coupled to the opposite end of the cored wire,
• wherein the first metal tube has a yield force of at least 140 Newtons (N), where the yield force is defined as the product of the yield stress of the first metal tube and a cross-sectional area of the first metal tube, the cross-sectional area of the first metal tube being defined by a wall thickness of the first metal tube (CW1) and a total cross-sectional area defined by an outer diameter of the first metal tube (TC1), and the cross-sectional area of the first metal tube defined by the thickness of the walls of the first metal tube (CW1) is less than 45% of the total cross-sectional area defined by the outer diameter of the first metal tube (TC1), and
• wherein the filler layer has a density in the range of 0.3-1.1 g/cm3 and comprises a filler layer material which is an organic material having an ash content of not more than 10 mass-%.