Thermocouple _ instrument in use need to pay attention to those issues1

Thermocouple is a temperature sensing element, is a kind of instrument. It directly measuring the temperature and the temperature change turn signal thermocouple thermoelectric emf signal, through electrical instrument ( Secondary instrument) Convert the temperature of the measured medium. Thermocouple temperature measurement is the basic principle of two kinds of different ingredients of closed loop conductor material composition, when when there is a temperature gradient at both ends, loop will have an electric current passes through, the existed between the electromotive force on both ends - Thermoelectric emf, this is the so-called seebeck effect ( Seebeckeffect) 。 Two different components of homogeneous conductor electrode as heat, the temperature is higher for work at the end of the end, one end of the low temperature as the free end, usually free end under a constant temperature. According to the thermoelectric emf as a function of temperature, the thermocouple indexing table; Indexing table is free end temperature at 0 ℃, under the condition of different thermocouples with different indexing table. Stop temperature measurement of the thermocouple is applying this truth, this directly used as a measurement of the medium temperature in the call to sing at the end of the work side, the other end is called the cold end. Cold end daily with performance instrument, instrument, electronic calculating machine and other supporting application, direct measurement of all kinds of yield process of 0 1300 degrees within the liquid, steam and gas medium with the name of the solid temperature. And thermocouple in petroleum, chemical, steel, paper, thermal power, nuclear power, and so on widely, lost people in the process of production of temperature measurement more accurate, convenient and insurance. Three major advantages and functions of K type thermocouple type K thermocouple has a certain application in multiple industries, with the continuous development of The Times in recent years, the amount of K type thermocouple is constantly rising, the scope of application is also more widely. The advantages of K type thermocouple itself is also a lot of. K type thermocouple is one of the industry commonly used temperature detecting element. Must go together with secondary instrument, its advantage is that (1) K type thermocouple measurement precision is high. Because of thermocouple direct contact with the object being measured, not affected by intermediate medium. (2) K type thermocouple measurement range. The commonly used thermocouple from - 50 ~ + 1600 ℃ can be continuous measurement, some special thermocouple low measurable to - 269℃( Such as gold iron nickel chrome) Up to + 2800 ℃ ( Such as tungsten - Rhenium) 。 (3) K type thermocouple simple structure, easy to use. Thermocouple is usually composed of two different kinds of metal wire, but is not limited by the size and the beginning of, outside has protective casing, which are very convenient. K type thermocouple in according to the temperature measurement range and accuracy, the corresponding index number of thermocouples when using the K type thermocouple temperature at 1300 ~ 1800 ℃, requirements and high accuracy, generally choose B type thermocouple; Required accuracy is not high, atmosphere and allow tungsten-rhenium thermocouples are available, and higher than 1800 ℃ generally choose tungsten-rhenium thermocouples; Temperature at 1000 ~ 1300 ℃ requires accuracy and higher available S type thermocouple and N type thermocouple; Under 1000 ℃ in general with K type thermocouple and N type thermocouple, below 400 ℃ general use E type thermocouple; Negative temperature under 250 ℃, and usually measured in T thermocouple, T thermocouple during low temperature stability and high precision.