Weak current College】 【thermometer classification and use of common.

<br> With the development of science and technology and the needs of modern industrial technology, temperature measurement technology is continuously improved and enhanced. Due to the measuring range has become an increasingly widespread, according to different requirements, and create a different need for temperature .measuring instruments. Here are several. <br> <br> 1, gas thermometer: <br> <br> More hydrogen or helium for temperature measuring material, because hydrogen and helium liquefaction temperatures are low, and close to absolute zero, so it .is a wide range of temperature measurement. This high accuracy thermometer, used for precision measurements. <br> <br> 2, resistance thermometer: <br> <br> Divided into metal resistance thermometers and semiconductor resistance thermometers based resistance values with temperature changes .this behavior. Metal thermometer mainly useful for Platinum, gold, copper, nickel, rhodium pure metal and iron, phosphorus bronze; semiconductor thermometer key carbon, germanium, etc. Resistance thermometer with convenient and reliable, have been widely used. Its measurement range from .-260 ° c to 600 ℃.  <br> <br> 3, thermocouple thermometer: <br> <br> Is an industry wide application of temperature measurement instruments. Use thermoelectric phenomena. Two different wires welded together to form work-and .the other at both ends and measuring instruments connected to form a circuit. The work ends on the measured temperature at work and the free end temperature at the same time, the electromotive force, which is current through the loop. By measuring the amount of electricity ., use of a known temperature at, you can test the temperature of another Department. This thermometer used copper-constantan, Fe-cuni, NI Ming-constantan, gold, cobalt, copper, Platinum - - - - rhodium, etc. It applies .to the temperature difference between the larger two substances, used for high temperature and low turbidity measurement. Some of the thermocouple can measure up to 3000 ° c of temperature, can measure close to absolute zero temperature.  <br> <br> 4. .high temperature thermometer: <br> <br> Is designed to measure temperatures above 500 degrees centigrade thermometer, optical thermometer, colorimetric thermometers and radiation thermometer. High temperature thermometer principle and structure are quite complex, there is no longer discussion. The measuring range of .500 ° c to 30 ° c above, does not apply to low-temperature measurement. <br> <br> 5. dial thermometers: <br> <br> Is shaped like the dashboard in thermometers, also known as the thermometer to measure .temperature, is the principle of free metal. It is a bi-metal blade as a thermal element, used to control the pointer. Bi-metal blade is often used copper and iron plate riveted together, and copper tablets in the left, iron tablets .in the right. Because of the effect of heat on copper than iron obvious, when the temperature rises, the copper plate stretch bending iron tablets to the right, the pointer in the bi-metal blade, along with the right deflector (point to high .temperature); on the contrary, the temperature low and pointers in the bi-metal blade, along with the left deflection (links to at low temperature). <br> <br> 6. glass tube thermometer: <br> <br> .Glass tube thermometer is free to implement the principle of temperature measurement. As a result of temperature coefficient of linear expansion of the media and the boiling point and freezing point, so we common glass tube thermometer: kerosene thermometers, mercury thermometers, IR pen water thermometer .. He has the advantage that the structure is simple, easy to use, the relatively high measurement accuracy, low price. The disadvantage is that the upper and lower limits and precision measurement by glass quality and temperature of the nature of the medium. And cannot .be remote, fragile. <br> <br> 7. pressure thermometer: <br> <br> Pressure thermometer is the use of closed containers for liquid, gas or vapor heated after volume expansion or pressure changes as the measuring signal. Its basic .structure is composed of warm buns, capillary and indicates the table is made up of three parts. It was the first to apply to the production process one method of temperature control. Pressure measurement system remains in place instructions and control a wide range of application temperature .measurement method. The advantage of pressure thermometer: simple structure, high mechanical strength, not afraid to shake. Prices are low, without external energy. Disadvantages are: measuring range is limited, usually in the-80 ~ 400 ° c; heat loss big .response time is slow; instrument seal system (temperature packages-capillary, spring tube) damage difficult to repair, you must replace; measuring accuracy is affected by the ambient temperature, temperature effects package installation location, the relatively low accuracy; capillary transfer distance limitations .. Pressure thermometer frequently work should be in the range of 1/2--3/4, as far as possible, in the show table and warm Pack is level. The installation of the package installation bolts will make the temperature loss leads to temperature .is not accurate, the installation should insulate and try to make the package work temperature without vibration environment. <br> <br> 8. turn the thermometers: <br> <br> Turn the thermometer is a curly-made of metal pieces. .Bi-metal blade fixed at one end and the other end to a pointer. Two metal sheets for expansion, at different temperatures, leading to the degree of curl bi-metal blade, the pointer is then refers to a different location on the dial, .dial the readings on the impracticality of its temperature. <br> <br> 9, semiconductor thermometer: <br> <br> Semiconductor's resistance to change and metal, temperature rise, but their resistance is reduced, and the relatively large changes. Therefore .a small temperature changes can make a significant change in resistance, made thermometers have higher precision, often called the heat exchanger. <br> <br> 10, thermocouple thermometer: <br> <br> Thermocouple thermometer is composed of two different metals is .connected with a sensitive voltage meter. Metal contacts at different temperatures, metal ends produce different potential difference. Potential difference is very small, so having sensitive voltage meter can be measured. By voltage meter readings, we can know the temperature. <br> < .br> 11, optical pyrometer: <br> <br> Body temperature to high to be issued by a large number of visible light, it can be used to measure the size of its radiation in order to determine its temperature, this type of thermometer .is the optical thermometer. This thermometer is equipped with a red filter telescope and a set of small light bulb, current meter and variable resistor circuit. Use before the establishment of different filamentBrightness corresponds to the temperature and current meter readings on relationships. Use the telescope .on the test, adjust the resistance, the brightness of the lamp and the test of the same, then they can from the meter reading of the temperature to be measured. <br> <br> 12, LCD thermometer: <br> <br .> Made with different formulations, its phase transition of liquid temperature, the transformation, its optical properties will change so that the LCD looks changing color. If you set different transformation temperature of liquid crystal coating on one sheet of paper, by liquid crystal color changes ., we can know the temperature. The advantages of this thermometer is reading easy, but with the disadvantage is the lack of accuracy, commonly used for ornamental fish, used to indicate that the water temperature. <br> <br> <br>.