Explain several requirements for the installation of thermocouples and thermal resistors

tothermocoupleWhen installing thermal resistors, attention should be paid to ensuring accurate temperature measurement, safety, reliability, and easy maintenance, without affecting 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 depth of insertion of the shallow insertion thermocouple protective sleeve into the main steam pipeline should not be less than 75mm; the standard insertion depth of the hot sleeve thermocouple 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.