Möjliga faktorer som leder till felaktig temperaturmätning av termoelement av K-typ

As a typical temperature instrument, K-type thermocouple has been widely used in industrial production measurement due to its unique performance. However, in the process of using thermocouples in industrial enterprises, K-type thermocouples often have inaccurate temperature measurement. In order to avoid errors as much as possible, we must know what are the factors that cause inaccurate temperature measurement of thermocouples? Låt oss förklara det här problemet för dig .

1. fel introducerade genom felaktig installation

Thermocouples should not be installed too close to the door and heating. The insertion depth should be at least 8 to 10 times the diameter of the protection tube. The installation position and insertion depth cannot reflect the actual temperature of the furnace. The gap between the thermocouple protection sleeve and the wall is not filled with insulating materials, resulting in heat overflow or cold air intrusion in the furnace. Therefore, the gap between the thermocouple protection tube and the furnace wall hole should be blocked with insulating materials such as refractory mud or asbestos rope to prevent hot and cold air convection from affecting the accuracy of temperature measurement. The installation of thermocouples should avoid strong magnetic fields and strong electric fields as much as possible. Termoelement och kraftkablar bör inte installeras i samma ledning för att undvika störningar och fel . Termoelement kan inte installeras i områden där det uppmätta mediet sällan flyter . när du använder termokaparten för att mäta temperaturen i röret i röret måste termokopplingen installeras mot flödesrörelsen och fullt in kontakten med 10 {})

2. Fel som introduceras genom isoleringsförsämring

Till exempel, om det finns för mycket smuts eller saltrester på termoelementets skyddsrör och trådteckningsplattan, kommer isoleringen mellan termoelementets poler och ugnsväggen att vara dålig, vilket är mer allvarligt vid höga temperaturer . Detta kommer inte bara att orsaka förlusten av termoelektrisk potential utan också introducera interferens .} felet orsakas av hundratals})

3. fel introducerade av termisk tröghet

Due to the thermal inertia of the thermocouple, the indicated value of the instrument lags behind the change of the measured temperature. This effect is particularly prominent when performing rapid measurements. Therefore, thermocouples with thinner thermocouples and smaller protection tube diameters should be used as much as possible. When the temperature measurement environment permits, the protection tube can even be removed. Due to the measurement lag, the amplitude of the temperature fluctuation detected by the thermocouple is smaller than the amplitude of the furnace temperature fluctuation. The greater the measurement lag, the smaller the amplitude of the thermocouple fluctuation, and the greater the difference from the actual furnace temperature. When using a thermocouple with a large time constant to measure or control temperature, although the temperature displayed by the instrument fluctuates very little, the actual furnace temperature may fluctuate greatly. In order to accurately measure the temperature, a thermocouple with a small time constant should be selected. The time constant is inversely proportional to the heat transfer coefficient and is proportional to the diameter of the hot end of the thermocouple, the density of the material and the specific heat. If you want to reduce the time constant, in addition to increasing the heat transfer coefficient, the most effective way is to minimize the size of the hot end. In use, materials with good thermal conductivity, thin tube walls and small inner diameter protective sleeves are usually used. In more precise temperature measurements, bare wire thermocouples without Skyddshylsor används, men termoelement är lätt skadade och bör kalibreras och bytas ut i tid .

Genom ovanstående tre punkter på analysen av faktorer som leder till termoelementfel av K-typ hoppas jag att det kommer att vara till hjälp för allas arbete och studie .