Ceramic Sheath for Thermocouple and Resistance thermometer
Ceramic sheath’s main application ranges between 1000 to 1800 ºC.
They may be in direct contact with the medium or may be used as a gas-tight inner sheath to separate the thermocouple from the actual metal protection tube.
They should be mounted in hanging position above 1200ºC to prevent distortion or fracture due to bending stresses.
Even hairline cracks can lead to contamination of the thermocouple resulting in drift or failure.
The wall thickness of the material is also important; thin walled tube is preferable to larger wall thickness.
Cracks frequently developed if they are given excessively rapid temperature changes when they are quickly removed from hot furnace.