The difference between heat-shrouded thermocouple and armored thermocouple

The thermoelectric potential of the armored thermocouple will increase as the temperature of the measuring end increases. The magnitude of the thermoelectric potential is only related to the material of the thermocouple conductor and the temperature difference between the two ends, and has nothing to do with the length and diameter of the thermocouple.
The two ends of the conductors of two different components are welded to form a loop. The direct temperature measurement end is called the working end, and the terminal end is called the cold end, also known as the reference end. When there is a temperature difference between the working end and the reference end, a thermal current will be generated in the loop. When connected to a display instrument, the instrument will indicate the corresponding temperature value of the thermoelectric potential generated by the thermocouple.
For the temperature measurement of high-temperature, high-pressure and high-speed fluids (such as main steam temperature), in order to reduce the resistance of the protective sleeve to the fluid and prevent the protective sleeve from breaking under the action of the fluid, the protective tube can be shallowly inserted or the heat-sheathed thermocouple can be used. The shallow insertion thermocouple protective sleeve should be inserted into the main steam pipe at a depth of not less than 75mm; the standard insertion depth of the heat-sheathed thermocouple is 100mm;
The structural principle of the armored thermocouple
It is made of conductor, high-insulation magnesium oxide, and outer jacket 1Cr18Ni9Ti stainless steel protective tube, which are drawn in one piece many times. The armored thermocouple product mainly consists of a junction box, a terminal block and an armored thermocouple, and is equipped with various installation and fixing devices.
Armored thermocouples are divided into insulated and shell-connected types.
It has many advantages such as bending, high pressure resistance, fast thermal response time and durability. It is used as a temperature sensor like industrial use. It is usually used with display instruments, recording instruments and electronic regulators. At the same time, it can also be used as a temperature sensing element. It can directly measure the temperature of liquid, steam and its gas medium and solid surface in the range of 0℃~800℃ in various production processes. Compared with, armored thermocouples have the advantages of bendability, high pressure resistance, short thermal response time and durability.
Thermocouple temperature measurement principle
is based on the thermoelectric effect. When two different conductors or semiconductors are connected into a closed loop, when the temperatures at the two junctions are different, a thermoelectric potential will be generated in the loop. This phenomenon is called the thermoelectric effect, also known as the Seebeck effect.
As a temperature measurement sensor, armored thermocouples are usually used in conjunction with temperature transmitters, regulators and display instruments to form a process control system to directly measure or control the temperature of fluids, steam and gas media and solid surfaces in the range of 0-1800℃ in various production processes.
Armored thermocouples have many advantages such as bendability, high pressure resistance, fast thermal response time and durability. Like industrial assembled thermocouples, they are used as temperature measurement sensors and are usually used in conjunction with display instruments, recording instruments and electronic regulators.
Calibration method of armored thermocouple
Calibration method and device for metal melt rapid armored thermocouple.
The device is mainly composed of a flat heating coil that can accommodate two quartz tubes at the ends of the measured couples, two armored thermocouples with the same shape as the measured couples, and a corresponding temperature control display output device.
Calibration method:
First, use two calibration thermocouples to find the points in the flat heating coil that make the two calibration couples have the same thermoelectric potential, replace one of the calibration couples with the measured couple, and when other conditions remain unchanged, wait for the reading of the measured couple to stabilize and compare it with the reading of the calibration couple to know whether the value of the measured couple is accurate.
Features:
a. The device is composed of a flat heating coil, a pair of calibration armored thermocouples, and a temperature control display output device.
b. The verification method is to first insert two calibration thermocouples from both ends of the heating coil to each other so that the hot ends of the armored thermocouples are in contact. By changing the position of the calibration thermocouples in the heating coil, the thermoelectric potentials of the two calibration thermocouples are made the same. Replace one of the calibration thermocouples with the measured fast thermocouple, read its thermoelectric potential value in the stable state and compare it with the thermoelectric potential of the calibration thermocouple to know the accuracy of the measured fast armored thermocouple.