Wednesday, December 29, 2010
Weak current College】 【accurately measure temperature techniques】.
<br> <br>-When the luminous surface temperature, such as aluminum and stainless steel, surface reflection affect infrared thermometer reading. Before reading the temperature, you can put a strip of metal surface, the temperature equilibrium, measurement temperature Strip area. .<br>-To infrared thermometer can be accessed from the kitchen to the frozen zone walking up and down will still be able to provide precise temperature measurement, in the new environment after a period of time to reach the temperature of the balance after the measurement .. It is best to put the thermometer used in the workplace. <br> Use infrared thermometer reads the internal temperature of the liquid food, like a soup or sauce, stir, then you can measure surface temperature. The thermometer away from steam to avoid .pollution of the lens, resulting in incorrect readings. <br> <br> How to properly select infrared thermometer <br> <br> Infrared temperature measurement technology in product quality control and monitoring, device online troubleshooting, security, protection and conservation of energy .is playing an important role to play. In the last 20 years, non-contact infrared thermometer is technically is the rapid development, performance continues to improve, scope of application is expanding, the market share year on year growth. Compared to contact temperature measurement ., infrared temperature measurement with fast response times, contactless, use safety and long life and other advantages. <br> <br> Non-contact infrared temperature measurement products include portable, on-line and scan-three series, and is equipped with various .accessories and appropriate computer software, each series and the various models and specifications. In different specifications of various types of thermometer, the proper selection of infrared thermometer model to the user, is very important. Here is how to correctly select thermometer type of steps for .the purchaser. <br> <br> Infrared thermometer working principle <br> <br> Understanding Group thermometer works, technical indicators, environmental conditions and the operation and maintenance to help customers in the proper selection and use of infrared thermometer. <br> .<br> All temperature above absolute zero (-273 ° c) objects are kept to the surrounding space issue infrared radiation energy. Objects of infrared radiation characteristics of a radiated energy's size and distribution by wavelength of a and its surface temperature is very closely related .. Thus, through the object's own radiation measurement of infrared energy, will be able to accurately measure the surface temperature, this is the infrared radiation Thermometry is based on an objective basis. <br> <br> Law of blackbody radiation: <br> .<br> Blackbody is an idealization of the radiator, it absorbs all wavelengths of radiation energy, did not reflection and through energy, its surface emissivity is 1. It should be noted that, in nature and does not exist the real bold, but in .order to clarify and obtain infrared radiation distribution, in theory you must select the appropriate model, which is the body cavity of Planck's radiation of quantum oscillator model to export the Planck's law of blackbody radiation, wavelength said of blackbody radiation spectra, this is all theory .of infrared radiation, therefore calls the law of blackbody radiation. <br> <br> Object emissivity effect on radiation Thermometry: <br> <br> The nature of the actual object, not a blackbody. All the actual object of radiation wavelength than .dependent radiation and temperature of a body, and form the object of material types, preparation method, thermal process, as well as surface and environmental conditions and other factors. Therefore, in order to make the blackbody radiation law applies to all actual objects, you .must introduce a and material properties and surface condition of scaling factors, namely the emissivity. The coefficient indicates that the actual object in thermal radiation and how closely the blackbody radiation, its value is zero and less than 1 between the numeric value. According to the .radiation law, as long as known material emissivity, know any objects of infrared radiation. <br> <br> The main factor affecting emissivity in: <br> <br> Material type, surface roughness, physical and chemical structure and material thickness, .etc. <br> <br> When using infrared radiation thermometer to measure the target temperatures must first measure goals in the wavelength range of infrared radiation, and then by the thermometer calculated temperature of the measured object. Monochrome thermometer and-band radiation levels in .proportion to: two color Pyrometer with two wavelengths of radiation is proportional to volume ratio. <br> <br> Infrared system: <br> <br> Infrared thermometer by the optical system, photoelectric detectors, signal amplifiers and signal processing, display the .output. Optical system brings together its vision of infrared radiation energy, field of view of the size of the thermometer of optical parts and its location. Infrared energy is focused in photoelectric detector and transformed into the corresponding signal. The signal amplifier and signal processing circuit ., and in accordance with the instruments of the algorithm and target neiliao emissivity correction after changes to the measured temperature value of the target. <br> <br> Select infrared thermometer can be divided into three areas: <br> <br> Performance indicators ., such as temperature, spot size, working wavelength, measurement accuracy, response time, etc; environmental and working conditions, such as the ambient temperature, window, display, and output, the protection of the annex, etc; other options, such as .easy to use, maintenance and calibration of performance and price, but also on the thermometer of choice to produce certain effects. As technology and constantly evolving, infrared thermometers best design and development provides users with a variety of functional and versatile instrument, broadened the choice .. <br> <br> Determine the temperature measuring range: <br> <br> Measuring range is the thermometer one of the most important performance indicators. If TIME (times), Raytek (Raytek) product range is-50 ° c- .+ 30 ° c, but this is not a type of infrared thermometer. Each type of thermometer has its own specific temperature range. Therefore, users of the measured temperature range should be considered accurate, comprehensive, neither too narrow, and not too wide. .According to the law of blackbody radiation, in the spectra of short wavelength radiation caused by temperature changes will exceed energy by emissivity errors are caused by changes of radiation energy, therefore, when you try to use temperature short is good. <br> <br .> Determine the target size: <br> <br> Infrared thermometer in accordance with the principle can be divided intoMonochrome thermometer and two color pyrometer (radiation colorimetric thermometer). For monochrome thermometer for temperature measuring in the target area being measured should be filled with .thermometer field of view. Recommended that the measured size of the target size more than 50% of the field as well. If the target size is less than the field of view, the background radiation energy will enter the thermometer of acoustic interference temperature readings are .supported, resulting in errors. On the contrary, if the target field is larger than the thermometer, thermometer is not affected by the measure the area outside the influence of the background. <br> <br> For Raytek (Raytek) two-color .pyrometer, temperature is composed of two independent of wavelength band radiation energy ratio. So when the measured goal is very small, no full-scene, measuring path on fumes, dust, blocking on radiation energy attenuation, will not affect the measurement results. Even .energy attenuation up to 95% of cases, will still be able to guarantee the required temperature measurement accuracy. For target small, and is in motion or vibration of goals; sometimes depending on venue motion, or may remove part of the target field, under .these conditions, the use of two-color thermometer is the best choice. If the thermometer and the destination is not possible to directly target, measuring channel bending, narrow, blocked etc., two-color fiber optic thermometer is the best choice. This .is due to its diameter is small, flexible, and can be bent, barrier and collapse of channel transmission light radiation energy, so you can measure difficult to access, conditions or toward the goal of the electromagnetic field. <br> <br> Determine .the optical resolution (distance and sensitive) <br> <br> Optical resolution by the ratio of D and S is determined, to the target temperature measurement of the distance between the measuring spot diameter D and S. If the thermometer as environmental conditions must .be installed away from the target, but also to measure small goals, you should select the high optical resolution of the thermometer. Optical resolution is higher, ie increase D: S ratio, thermometer, the higher the costs. <br> <br> .Wavelength range: <br> <br> The target material and surface properties of emissivity determines the thermometer of spectral response or wavelength. For high reflectivity alloy material, with low or changing emissivity. In the high temperature area, the best measurement of metals is .the near-infrared wavelengths, optional 0.18-φ1.0 .1 μm wavelength. Other temperature can choose 1.6 2.2 μ μ m, m and 3.9 .1 μm wavelength. Because some of the materials in a certain wavelength is transparent, infrared energy will penetrate these .materials, such materials should choose special wavelength. If the internal temperature measuring glass selection 10 μ μ m and 2.2 m and 3.9 μ m (measured to very thick glass, otherwise they will be) wavelength; measuring glass internal temperature selection | μ5.0 ..1 μm wavelength; measuring low District selection 8-14 .1 μm wavelength is appropriate; and if the measuring polyethylene plastic film selection 3.43 .1 μm wavelength, polyurethane vinegar chosen 4.3 μ m or 7.9 .1 μm wavelength. Thickness exceeding 0.4mm selection 8-14 ..1 μm wavelength; and if in the measurement of flame C02 using narrowband 4.24-4.3 .1 μm wavelength, log fire in the C0 with narrowband 4.64 .1 μm wavelength, measurement of flame in N02 used 4.47 .1 μm wavelength. <br> <br> .Determine response time: <br> <br> Response time means infrared thermometer on the measured temperature change reaction speed, defined as reaching the final reading of 95% of the energy it takes time, and photoelectric detector and signal processing circuits and displays system time .constant. New infrared thermometer up to 1ms response time. This is not as simple as contacting temperature measurement method, which is much faster. If the target of the campaign quickly or measuring the target of rapid heating, to choose the quick response infrared thermometer, .otherwise can not reach enough signal response, will reduce the measurement precision. However, not all applications require quick response infrared thermometer. For static or target thermal process exists when the thermal inertia, the thermometer of response time to relax. Thus, the infrared thermometer .response time to select and test goals. <br> <br> Signal processing functions: <br> <br> Measurement of discrete process (such as a parts production) and continuous process, requiring infrared thermometer with signal processing functions (such as peak .hold, Gu values, average). If the temperature of the glass on the conveyor belt, going to keep using peak, its temperature of output signals transmitted to the controller. <br> <br> Environmental criteria into account: <br> < .br> Thermometer environment conditions on measurement results have great impact, should be taken into account, and an appropriate settlement affect the measuring accuracy even damage caused by the thermometer. When the ambient temperature is too high, the presence of dust, smoke and steam conditions ., you can use vendor-supplied protection kits, water cooling and air cooling system and air blowing machine and other attachments. These attachments can effectively address the environmental impact and to protect the thermometer for accurate temperature measurement. In determining the attachment, should, to .the extent possible require standardized service in order to reduce installation costs. When the smoke, dust or other particles reduce measuring energy signals, two color pyrometer is the best choice. Electromagnetic fields, noise, vibration or difficult to access environmental conditions, or other abusive .conditions, fibre-color thermometer is the best choice. <br> <br> In sealed or dangerous materials (such as containers or vacuum tank), thermometer observing through the window. Materials must be of sufficient strength and energy through the thermometer working wavelength .range. To determine whether it requires the operator through the window to observe, to select the appropriate installation position and window material, to avoid interaction. In low-temperature measurement applications, often using Ge or Si material as window, impermeable to visible light, .the human eye cannot, through observation of the target window. If an operator needs through window target, should use both through infrared radiation through visible light optical materials, such as the should use both through infrared radiation through visible light optical materials, such as the .ZnSe or BaF2, etc. as window material. <br> <br> Operation is simple and easy to use: <br> <br> Infrared thermometer should be intuitive, simple operation, easy to use by the operator, including a portable infrared .thermometer is a thermometric and set display output as one of the small, lightweight, conducted by the person carrying the instrument temperature measurement, in the display panel to display the temperature and output rangeTemperature information, available through the remote control or via the computer software program .. <br> <br> In environmental conditions and complex cases, you can select the measuring head and monitor the system separately, to facilitate the installation and configuration. To select the existing control device matching signal output form. <br> <br> .Infrared radiation thermometer calibration: <br> <br> Infrared thermometer calibration must pass in order to enable it to properly display the temperature of the measured object. If the thermometer in the use of a temperature variance that may be returned to the manufacturers or repair .center calibration again. <br> <br> <br> <br> <br>.