HYDAC HYDAC temperature sensors can signal this reaction in different ways

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Germany HYDAC HYDAC temperature sensor can do signal conversion for this reaction in different ways

The temperature sensor (temperature transducer) refers to the sensor that can sense the temperature and convert converts it into a usable output signal from the sensor. The HYDAC temperature sensor is the core part of the temperature measuring instrument and has several variants. According to the measurement method, it can be divided into two categories: contact type and non-contact type. According to the characteristics of sensor materials and electronic components, it can be divided into two types: thermal resistance and thermocouple.

Contact type

Contact type HYDAC temperature sensor The sensing part has good contact witht the measured object, also called a thermometer.

The thermometer achieves heat balance by conduction or convection, so that the indicated value of the thermometer can directly reflect the temperature of the measured object. In general, the measurement accuracy is high. Within a certain temperature range, the thermometer can also measure the temperature distribution in the object. However, large measurement errors will occur for moving bodies, small targets or objects with a small heat capacity. Commonly used thermometers are bimetallic thermometers, liquid-in-glass thermometers, pressure thermometers, resistance thermometers, thermistors and thermocouples. They are widely used in industry, agriculture, trade 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, petrochemical and other departments and theResearch on superconducting technology, cryogenic thermometers have been developed for measuring temperatures below 120K, such as cryogenic gas thermometers, steam pressure thermometers, acoustic thermometers, paramagnetic salt thermometers, quantum thermometers, low temperature resistance thermal resistance and low temperature thermocouples, etc. Cryogenic thermometers require small temperature sensitive elements , high accuracy, good reproducibility and stability. The thermal resistance of carbonized glass made of porous high silica glass carbonized and sintered is a kind of temperature sensitive element of the low temperature thermometer, which can be used to measure the temperature in the range of 1.6 ~ 300K.

Non-contact

The sensitive element and the measured object are not in contact with each other, also known as non-contact temperature measuring instrument. This instrument can be used to measure the surface temperature of moving objects,measure small targets and objects with small heat capacity or rapid temperature changes (transient), and can also be used to measure the temperature distribution of the temperature field.

The non-contact temperature measuring instrument is based on the basic law of black body radiation, which is called radiation thermometer. Radiation thermometer methods include brightness method (see optical pyrometer), radiation method (see radiation pyrometer), and colorimetric method (see colorimetric thermometer). All kinds of radiant temperature measurement methods can only measure the corresponding photometric temperature, radiant temperature or colorimetric temperature. Only the measured temperature of a black body (an object that absorbs all radiation and reflects no light) is the true temperature. To measure the actual temperature of the object, you must correct the surface emissivity of the material. The surface emissivityhowever, of a material does not only depend on temperature and wavelength, and it is also related to the surface condition, coating film and microstructure, so it is difficult to measure accurately. In automatic production, it is often necessary to use radiation thermometry to measure or control the surface temperature of certain objects, such as steel strip coil temperature, coil temperature, forging temperature in metallurgy, and the temperature of various molten metals in melting furnaces or crucibles. In these specific cases, measuring the emissivity of an object\'s surface is quite difficult. For automatic measurement and control of the temperature of the solid surface, an additional reflector can be used to form a black body cavity together with the measured surface. The effect of additional radiation can increase the effective radiation and the effective emissivity of the measured surface. Use the effective emissivcoefficient of validity to correct the measured temperature by the instrument, and finally get the actual temperature of the measured surface. The most typical additional mirror is a semicircular mirror. The diffuse radiation on the measured surface near the center of the sphere can be reflected to the surface by the hemispherical mirror to form additional radiation, increasing the effective emissivity. In the formula, ε is the surface emissivity of the material, and ρ is the reflectivity of the mirror. As for the radiation measurement of the actual temperature of the gas and liquid medium, the method can be used to insert the heat-resistant material tube to a certain depth to form a black body cavity. The effective emissivity of the cylinder cavity after reaching thermal equilibrium with the medium is calculated. With automatic measurement and control, this value can be used to calculate the measured boto correct the damping temperature of the cavity (ie medium temperature) to obtain the actual temperature of the medium.

Advantages of non-contact temperature measurement: The upper limit of the measurement is not limited by the temperature resistance of the temperature-sensitive element, so in principle there is no limit to the maximum measurable temperature. For high temperatures above 1800°C, non-contact temperature measurement methods are mainly used. With the development of infrared technology, radiant temperature measurement has gradually expanded from visible light to infrared, and is used under 700 °C to room temperature with high resolution.

Sensor designed according to the principle of metal expansion

Metal will produce a corresponding elongation after the ambient temperature changes, so that the sensor can perform signal conversion to this response in different ways.

Bi-metal plate sensor

Bi-metal plate is scomposed of two pieces of metal with different coefficients of expansion stuck together. As the temperature changes, material A expands more than the other metal. causing the sheet metal to bend. The curvature of the bend can be converted into an output signal.

Bi-metal rod and metal tube sensor

As the temperature increases, the length of the metal tube (material A) increases, while the length of the non-expanding steel rod (metal B ) does not increase, so that the linear expansion of the metal tube can be transferred by the change of position. This linear expansion can in turn be translated into an output signal.

Sensors designed by the deformation curves of liquids and gases

When the temperature changes, the volume of liquids and gases also changes.

Various types of structures can convert this change in expansion into a change in position, creating a poposition change output is produced (potentiometer, sense bias, baffle, etc.).

Thermocouples consist of two wires of dissimilar material welded together at the ends. Then measure the ring of the unheated partThe temperature of the heating point can be accurately determined. Since it must have two conductors of different materials, it is called a thermocouple. Thermocouples made of different materials are used in different temperature ranges and their sensitivities also vary. The sensitivity of the thermocouple refers to the change in the output potential difference when the temperature of the heating point changes by 1 °C. For thermocouples supported by most metallic materials, this value is approximately 5 to 40 microvolts/℃

Since the sensitivity of the thermocouple HYDAC temperature sensor has nothing to do with the thickness of the material, you should veryusing thin materials. available as HYDAC temperature sensor. Also due to the good ductility of the metal material used to make thermocouples, this small temperature measuring element has a certain reaction speed and can measure rapidly changing processes.

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