Sheathed thermocouples are characterized by their flexibility, high temperature resistance, fast thermal response time, and robustness. Like industrial assembled thermocouples, they serve as temperature sensors and are typically used in conjunction with display instruments, recording instruments, and electronic regulators. They can also be used as temperature sensing elements for assembled thermocouples. They can directly measure the temperature of liquids, steam, gaseous media, and solid surfaces within the range of 0℃ to 800℃ in various production processes, and should comply with the GB/T18404-2001 standard.
Sheathed Thermocouple Working Principle
The working principle of a sheathed thermocouple is that two conductors of different compositions are welded at both ends to form a circuit. The direct temperature measurement end is called the measuring end, and the wiring end is called the reference end. When there is a temperature difference between the measuring end and the reference end, a thermal current is generated in the circuit. When connected to a display instrument, the instrument will indicate the temperature value corresponding to the thermoelectric electromotive force generated by the thermocouple.
The thermoelectric electromotive force of a sheathed thermocouple increases with the temperature of the measuring end. The magnitude of the thermoelectric electromotive force depends only on the conductor material of the sheathed thermocouple and the temperature difference between the two ends, and is independent of the length and diameter of the thermoelectrode.
The structure of a sheathed thermocouple consists of conductors, insulating magnesium oxide, and a 1Cr18Ni9Ti stainless steel protective tube, which is drawn multiple times. The sheathed thermocouple product mainly consists of a junction box, terminal block, and sheathed thermocouple as the basic structure, and is equipped with various installation and fixing devices.
Sheathed thermocouples are divided into insulated type and grounded type.
Sheathed Thermocouple Main Technical Specifications
Temperature Measurement Range and Accuracy
|
Type |
Code |
Graduation |
Sheath Outer Diameter mm |
Common Temperature ℃ |
Max. Operating Temperature ℃ |
Allowable Deviation △t |
|
|
Measurement Range ℃ |
Tolerance Value |
||||||
|
Nickel-Chromium / Copper-Nickel |
WREK |
E |
≥Φ3 |
600 |
700 |
0～700 |
±2.5℃ or ±0.75%t |
|
Nickel-Chromium / Nickel-Silicon |
WRNK |
K |
≥Φ3 |
600 |
700 |
0～700 |
±2.5℃ or ±0.75%t |
|
Nickel-Chromium / Nickel-Silicon |
WRNK |
K |
≥Φ3 |
600 |
700 |
0～700 |
±2.5℃ or ±0.75%t |
