What are the installation methods and precautions for thermocouple and thermistor?

Attention should be paid to the installation of thermocouples and thermal resistors, which is conducive to accurate temperature measurement, safety, reliability, and easy maintenance, and does not affect equipment operation and production operations To meet the above requirements, the following points should be noted when selecting the installation location and insertion depth for thermocouples and thermal resistors:
1. In order to ensure sufficient heat exchange between the measuring ends of thermocouples and thermal resistors and the measured medium, the location of the measuring points should be selected reasonably, and thermocouples or thermal resistors should be avoided as much as possible near dead corners of valves, elbows, pipelines, and equipment
2. Thermocouples and thermistors with protective sleeves have heat transfer and dissipation losses. In order to reduce measurement errors, thermocouples and thermistors should have sufficient insertion depth:
(1) For thermocouples used to measure the fluid temperature at the center of a pipeline, their measuring end should generally be inserted into the center of the pipeline (vertically or obliquely installed) If the diameter of the tested fluid pipeline is 200 millimeters, the insertion depth of the thermocouple or thermistor should be selected as 100 millimeters;
(2) For 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, shallow insertion of the protective tube or the use of a hot sleeve thermocouple can be adopted The shallow insertion type thermocouple protective sleeve should be inserted into the main steam pipeline to a depth of not less than 75mm; The standard insertion depth for hot sleeve thermocouples is 100mm;
(3) If it is necessary to measure the temperature of the flue gas inside the flue, even though the diameter of the flue is 4m, a thermocouple or thermistor can be inserted at a depth of 1m
(4) When the insertion depth of the measuring element exceeds 1m, it should be installed vertically as much as possible, or support frames and protective sleeves should be added

Installation methods for thermocouples and thermal resistors
Firstly, the dimensions of the thermocouple and thermistor screws should be measured, and the screw seat should be installed
2. Make holes in the pipeline to be measured according to the diameter of the screw seat
3. Welding of screw seat Insert the screw socket into the already drilled hole and weld it to the measured pipeline
4. Screw the thermocouple or thermistor into the welded screw seat
5. Connect the junction box of the thermocouple or thermistor according to the wiring diagram and connect it to the corresponding display instrument on the dial Note that the junction box should not come into contact with the wall of the tested medium pipeline, ensuring that the temperature inside the junction box does not exceed the range of 0-100 ℃ The outlet holes of the junction box should be installed facing downwards to prevent short circuits in the wiring terminals caused by poor sealing, water vapor and dust deposition