Heavily sheathed thermocouples for harsh environments. Types K, J, N, S, R. Ø1.0–8.0 mm. Custom-made, short lead time.
Along with resistance sensors, they are the most commonly used type of temperature sensor.
Thermo-control Körtvélyessy GmbH does not manufacture insulated cables itself, but purchases them pre-assembled from qualified partner companies. The cables are inspected upon receipt.
The test consists of two measurements. The first checks for a short circuit between the thermowires and the sheath. Next, the insulation resistance is measured at room temperature using test voltages of 75 V and 500 V to verify that it complies with the tolerances specified in DIN EN 611515.
Once the inspection is complete, the sheathed thermocouples are assembled according to the standard designs. If special designs are required, we will be happy to discuss and manufacture them upon receipt of your request.
The product overview is loaded dynamically.
The specification is structured as follows:
16
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MM
XX
TT
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DDD
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F
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LLLL
CC
Specification tables are loaded dynamically.
Manufacturing
Sheathed thermocouples are made from sheathed cables. These consist of a metal sheath and a core of ceramic insulating material. The actual thermowires are embedded in this insulating material, which in many cases consists of high-purity magnesium oxide (MgO).
Due to its filling, the sheathed thermocouple can be bent without causing a short circuit in the internal thermowires. The bending radius—12 times the diameter—is relatively tight, making it easy to attach to workpieces, for example.
Thinner sheathed thermocouples are therefore ideal for surface measurements. However, care must be taken to ensure that at least 5 times the diameter is in contact with the surface; otherwise, measurement errors will occur.
The sheathed cable is manufactured by rolling or drawing a metal tube. Ceramic sleeves are inserted into this tube, which has a diameter of approximately Ø80 mm, and thermocouple alloy wires are threaded through these sleeves.
Diagram of a blank for the manufacture of sheathed thermocouple cables
Through the rolling or drawing of the blank, the ceramic sleeves are literally pulverized and encase the existing thermowires. Assembly is completed by cutting a length of the wire. The thermowires are welded together at one end, thus forming the thermocouple.
Depending on the requirements, either the chamber containing the welding point is filled with MgO powder and sealed with a cap, or the cap is placed directly over the welding point. In the first case, this is referred to as an insulated measuring tip; in the latter, as a grounded measuring tip. Our sheathed thermocouples come standard with an insulated measuring tip.
Longitudinal cross-section of a sheathed thermocouple showing the cap and weld pointDiagram of a blank for the manufacture of sheathed thermocouple cablesLongitudinal cross-section of a sheathed thermocouple showing the cap and weld point
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