German SIE sensors SIE models SIE prices

SIE sensors are devices that convert mass signals into measurable electrical signal outputs. When using sensors, the actual working environment of the sensor should be considered first. This is crucial for the correct selection of load cells, as it affects whether the sensor can operate normally, its safety and service life, and even the reliability and safety of the entire weighing system. There are qualitative differences between the old and new national standards in the basic concepts and evaluation methods of the main technical indicators of load cells. The main types include S type, cantilever type, spoke type, plate ring type, membrane box type, bridge type, and column cylinder type.

SIE sensor classification

1) Contact type: The sensing part of a contact temperature sensor has good contact with the object being measured, also known as a thermometer. The thermometer reaches thermal equilibrium through conduction or convection, so that the reading of the thermometer can directly indicate the temperature of the object being measured. Generally, the measurement accuracy is high. Within a certain temperature measurement range, the thermometer can also measure the internal temperature distribution of the object. However, for moving objects, small targets, or objects with very small heat capacity, large measurement errors will occur. Commonly used thermometers include bimetallic thermometers, glass liquid thermometers, pressure thermometers, resistance thermometers, thermistors, and thermocouples. They are widely used in industry, agriculture, commerce, and other sectors. People also often use these thermometers in daily life. With the wide application of cryogenic technology in national defense engineering, space technology, metallurgy, electronics, food, medicine, petrochemicals, and other departments, as well as research on superconducting technology, cryogenic thermometers for measuring temperatures below 120K have been developed, such as low-temperature gas thermometers, vapor pressure thermometers, acoustic thermometers, paramagnetic salt thermometers, quantum thermometers, low-temperature thermal resistors, and low-temperature thermocouples. Cryogenic thermometers require sensing elements with small volume, high accuracy, good reproducibility, and stability. A carburized glass thermal resistor made by carburizing and sintering porous high-silica oxygen glass is a type of sensing element for cryogenic thermometers, which can be used to measure temperatures in the range of 1.6 to 300K. 2) Non-contact type: Its sensitive element does not come into contact with the object being measured, also known as non-contact temperature measuring instruments. This type of instrument can be used to measure the surface temperature of moving objects, small targets, objects with small heat capacity, or objects with rapid temperature changes (transient), and can also be used to measure the temperature distribution of temperature fields. The most commonly used non-contact temperature measuring instruments are based on the basic laws of blackbody radiation and are called radiation temperature measuring instruments. Radiation temperature measurement methods include the brightness method (see optical pyrometer), the radiation method (see radiation pyrometer), and the colorimetric method (see colorimetric thermometer). Various radiation temperature measurement methods can only measure the corresponding luminous temperature, radiation temperature, or colorimetric temperature. Only the temperature measured for a blackbody (an object that absorbs all radiation and does not reflect light) is the true temperature. If you want to determine the true temperature of an object, you must correct for the emissivity of the material surface. The emissivity of the material surface depends not only on temperature and wavelength, but also on surface state, coating, and microstructure, making it difficult to measure precisely. In automated production, radiation temperature measurement is often used to measure or control the surface temperature of certain objects, such as the rolling temperature of steel strips in metallurgy, roll temperature, forging temperature, and the temperature of various molten metals in smelting furnaces or crucibles. In these specific cases, measuring the emissivity of the object's surface is quite difficult. For automatic measurement and control of solid surface temperature, additional mirrors can be used to form a blackbody cavity together with the measured surface. The influence of additional radiation can increase the effective radiation and effective emissivity of the measured surface. By using the effective emissivity to correct the measured temperature through the instrument, the true temperature of the measured surface can finally be obtained. The most typical additional mirror is a hemispherical mirror. The diffuse radiation energy of the measured surface near the center of the sphere is reflected back to the surface by the hemispherical mirror to form additional radiation, thereby increasing the effective emissivity. In the formula, ε is the emissivity of the material surface, and ρ is the reflectivity of the mirror. For radiation measurement of the true temperature of gas and liquid media, the method of inserting a heat-resistant material tube to a certain depth to form a blackbody cavity can be used. The effective emissivity of the cylindrical cavity after reaching thermal equilibrium with the medium is calculated. In automatic measurement and control, this value can be used to correct the measured cavity bottom temperature (i.e., medium temperature) to obtain the true temperature of the medium.

SIE sensor usage precautions

1) Errors introduced by improper installation: For example, the installation position and insertion depth of the thermocouple cannot reflect the true temperature of the furnace chamber. In other words, the thermocouple should not be installed too close to the door or heating area, and the insertion depth should be at least 8 to 10 times the diameter of the protection tube; the gap between the thermocouple protection tube and the wall is not filled with insulating material, causing heat overflow from the furnace or intrusion of cold air. 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 convection of cold and hot air from affecting the accuracy of temperature measurement; the cold end of the thermocouple is too close to the furnace body, causing the temperature to exceed 100℃; the installation of the thermocouple should avoid strong magnetic and electric fields as much as possible, so the thermocouple and power cables should not be installed in the same conduit to avoid introducing interference and causing errors; the thermocouple cannot be installed in areas where the measured medium flows very little. When using a thermocouple to measure the temperature of gas in a pipe, the thermocouple must be installed against the flow direction and fully contact the gas. 2) Errors introduced by poor insulation: If the thermocouple is insulated, excessive dirt or salt slag on the protection tube and pull plate causes poor insulation between the thermocouple poles and the furnace wall, which is more serious at high temperatures. This not only causes loss of thermoelectric potential but also introduces interference, and the resulting error can sometimes reach hundreds of degrees. 3) Errors introduced by thermal inertia: Due to the thermal inertia of the thermocouple, the instrument's indication lags behind changes in the measured temperature. This effect is particularly prominent during rapid measurements. Therefore, thermocouples with thinner thermoelectrodes and smaller protection tube diameters should be used as much as possible. If the temperature measurement environment permits, the protection tube can even be removed. Due to measurement lag, the amplitude of temperature fluctuations detected by the thermocouple is smaller than the amplitude of furnace temperature fluctuations. The greater the measurement lag, the smaller the amplitude of thermocouple fluctuations, and the greater the difference from the actual furnace temperature. When using a thermocouple with a large time constant for temperature measurement or control, although the temperature displayed by the instrument fluctuates very little, the actual furnace temperature may fluctuate significantly. To accurately measure temperature, a thermocouple with a small time constant should be selected. The time constant is inversely proportional to the heat transfer coefficient and directly proportional to the diameter of the thermocouple hot end, the density of the material, and the specific heat. To reduce the time constant, in addition to increasing the heat transfer coefficient, the most effective method is to minimize the size of the hot end. In use, materials with good thermal conductivity, thin-walled tubes, and small inner diameter protection sleeves are usually used. In more precise temperature measurements, bare wire thermocouples without protection sleeves are used, but thermocouples are easily damaged and should be calibrated and replaced in time. 4) Thermal resistance error: At high temperatures, if there is a layer of coal ash or dust on the protection tube, the thermal resistance increases, hindering heat conduction. At this time, the temperature reading is lower than the true value of the measured temperature. Therefore, the outside of the thermocouple protection tube should be kept clean to reduce errors.

SIE sensor industry applications

Temperature sensors are the earliest developed and most widely used type of sensor. The market share of temperature sensors greatly exceeds that of other sensors. Since the beginning of the 17 century, people have begun to use temperature for measurement. Supported by semiconductor technology, semiconductor thermocouple sensors, PN junction temperature sensors, and integrated temperature sensors have been successively developed in this century. Two conductors of different materials, if connected together at a certain point and heated at this connection point, a potential difference will appear at their unheated parts. The value of this potential difference is related to the temperature of the measurement point at the unheated part and the material of these two conductors. This phenomenon can occur over a wide temperature range. If this potential difference is measured precisely and the ambient temperature of the unheated part is measured, the temperature of the heating point can be accurately known. Because it requires two conductors of different materials, it is called a "thermocouple". Thermocouples made of different materials are used in different temperature ranges, and their sensitivities vary. Thermocouple sensors have their own advantages and disadvantages; their sensitivity is relatively low, they are easily affected by environmental interference signals, and they are also easily affected by the temperature drift of the preamplifier, so they are not suitable for measuring tiny temperature changes. Since the sensitivity of thermocouple temperature sensors is unrelated to the thickness of the material.

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