When the temperature sensor
is used to, there is often one way or the other problem, once appear, problem will affect the precision of instrument, so when the temperature sensor can be achieved at work * better measuring results, when used, the temperature sensor should pay attention to the following matters can guarantee * measurement: 1, the device error such as the location of the thermocouple device and the introduction of improper insertion depth can't reflect the reality of the furnace temperature, etc. , in other words, the thermocouple should not be in too close to the door and heating, the depth of the insert should be at least 8 ~ 10 times the diameter of the protection tube;
Thermocouple protection tube and the wall between the interval of missing adiabatic material overflow or cold air invading the furnace heating, so the space between the thermocouple protection tube and furnace wall hole used refractory mortar or insulating material such as asbestos rope jam to avoid cold and hot air convection and affect the accuracy of temperature measurement;
Thermocouple cold end is too close to the furnace temperature over 100 ℃;
Thermocouple device should as far as possible to avoid strong magnetic field and electric field, so should not be thermocouple and the power cable line in order to avoid interference caused by errors within the same catheter;
Thermocouple cannot device in few measured medium flow area, when measured with thermocouple tube gas temperature, must make the thermocouple against the flow direction of the device, and fully contact with the gas.
2, the error of the insulation deterioration and introduce such as thermocouple insulation, protection tube and anchor plate too much dirt or salt slag making thermocouple interelectrode poor insulation, the furnace wall at high temperatures is more serious, which not only causes the thermoelectric potential loss but also can introduce interference, the resulting error sometimes can reach on baidu.
3, the introduction of thermal inertia error due to thermal inertia of thermocouple instrument behind the change of the measured temperature, indicating value this influence is particularly acute in rapid measurement.
So should be used as thermal electrode is small, small thermocouple protection tube diameter.
Temperature measuring environmental permits, even protecting tube can be taken.
Due to measurement lag, using thermocouples detect temperature fluctuations of the amplitude of the furnace temperature fluctuation amplitude of the small.
Measurement lags behind, the greater the fluctuation amplitude of the thermocouple is smaller, and the actual temperature difference.
When using the time constant of thermocouple temperature or temperature control, instrument display temperature fluctuation is small, but the actual furnace temperature fluctuations can be quite large.
In order to accurately measure temperature, should choose small thermocouple time constant.
With thermocouple time constant is inversely proportional to the heat transfer coefficient, heat the density and specific heat is proportional to the diameter, material, such as to reduce the time constant, in addition to the increased heat transfer coefficient, * effective way is to try to decrease the size of the hot end.
For, usually USES the material with good thermal conductivity, wall thin, small diameter of the protective casing.
In the precision of temperature measurement, bare wire thermocouple for unprotected casing, but the thermocouple is easy to damage, should timely correction and replacement.
4 error at high temperature, thermal resistance, such as protecting tube with a layer of ash, dust attached to the above, the thermal resistance increase, hinder the heat conduction, when the temperature is lower than the true value of measured temperature value.
Therefore, we should maintain the cleanness of thermocouple protection tube outside, to reduce the error.
Wow, this sounds like a bit of a cruel question, but it is a vitally important question to ask yourself if you are struggling with your custom thermistor and you would like to stop the temperature sensor problem.
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