Causes of Thermocouple Measurement Errors

What is the most precise temperature measurement achievable? How are its model specifications indicated? What types of interfaces does it support? What are the key considerations when selecting a product model? How can measurement data be ensured to be accurate during installation? Although the PT100 sensor has a simple structure, various challenges can still arise in practical applications. For example, improper installation or operation can lead to significant measurement errors; even a PT100 that has passed metrological verification may fail during actual use due to incorrect handling. In nitriding or other nucleophilic gas environments, if proper precautions are not taken, K‑type thermocouples can also degrade due to conditional oxidation. To enhance measurement accuracy, reduce data errors, and extend the service life of PT100 sensors, users are required not only to possess instrument-specific technical skills but also to have expertise in physics, chemistry, materials science, and related fields. There are various raw materials used for PT100 temperature sensors, and different materials offer different measurement ranges. When selecting a product model, customers should specify the ideal measurement temperature, the typical operating temperature, and their requirements for measurement accuracy to determine which PT100 material is most suitable.

the reason for the error of pt100 data in China: poor installation and poor introduction: installation of instruments are also an important part, and everyone attaches great importance to it. poor installation will not only adversely affect the accuracy of measurement but also reduce the service life. for example, the installation part of pt100 and the insertion depth cannot reflect the actual room temperature in the furnace. in short, pt100 shall not be installed too close to the door and the heated area, and the inserted deep layer shall be at least 8~10 times of the diameter of the guarantee pipe; The distance between the protective waterproof casing of pt100 and the wall is not filled with thermal insulation chemicals, resulting in fire overflow or strong cold air intrusion in the furnace, therefore, the gap between pt100 guarantee tube and furnace mouth hole is blocked by thermal insulation chemicals such as refractory cement or graphite packing to prevent convection of hot and cold air and adversely affect the accuracy of temperature measurement. Pt100 air cooling is too close to the furnace wall to make the room temperature exceed 200 ℃; The installation of pt100 should avoid magnetic field and strong electrostatic field as far as possible, so pt100 and power cable should not be locked in each hose to prevent poor introduction influence; pt100 cannot be installed in an area where the measured substance has very little fluidity. when measuring the room temperature of the vapor in the tube with pt100, pt100 must be installed against the direction of water flow and sufficiently touched with the vapor.

domestic high-precision temperature controller data error: the worse the insulation layer, the worse the imported one: this reason is attributed to the product quality, because some people stipulate that the product quality should be good during the processing process, be sure to grasp the material tightly, such as pt100 insulation layer, to ensure that the pipe and cable box plate are dirty or too much salt slag leads to poor insulation layer between pt100 poles and furnace mouth, which is more serious at high temperature. This will not only cause the loss of thermoelectric potential difference, but also continue to introduce influence, resulting in poor sometimes reaching Baidu search. Product quality is the benchmark; only by selecting premium materials can you consistently deliver high-quality products.

domestic infrared thermometer due to data errors: poor introduction of thermal diffusion coefficient: this kind of situation is relatively complicated, and there are many factors on the spot, so we should consider key factors when selecting city commodity models, the main reason is that the thermal diffusion coefficient of pt100 makes the indicator light value technology of the instrument lag behind the change of the measured body temperature, and such adverse effects become more and more significant when measuring in a short time. Therefore, PT100 sensors with relatively thin thermocouple wires and a smaller sheath diameter should be selected whenever possible. When performing temperature measurements in a natural environment, the protective tube can even be removed. This is mainly due to measurement lag; the amplitude of room-temperature fluctuations measured with a PT100 is smaller than the amplitude of the temperature fluctuations themselves. The greater the measurement lag, the smaller the amplitude of the PT100 fluctuations, and the larger the discrepancy from the desired temperature control. When using a PT100 with a large time constant for temperature measurement or control, although the ambient temperature displayed by the instrument may fluctuate only slightly, the actual temperature control will exhibit significant fluctuations. To ensure accurate temperature measurement, a PT100 with a small steady-state error should be selected. The steady-state value is inversely proportional to the thermal conductivity and directly proportional to the diameter of the Pt100 hot end, the relative density of the material, and the specific heat at constant pressure. To reduce the steady-state value, in addition to increasing the thermal conductivity, the most effective approach is to minimize the dimensions of the hot end as much as possible. In practical applications, it is generally recommended to select waterproof sleeves made from materials with excellent thermal conductivity, featuring thin wall thickness and a small inner diameter. In temperature measurement for precision machinery, bare-wire PT100 sensors without protective sheaths are often used; however, these sensors are highly susceptible to damage and should be promptly calibrated and replaced.