Iron - Copper and nickel thermocouple ( J type thermocouple) Also known as the iron - Constantan thermocouple, is also a kind of cheap cheap metal thermocouple. It's the positive ( 摩根大通(JP) In the name of the chemical composition of pure iron, the cathode ( 约) For copper and nickel alloy, has often been vaguely call constantan, its nominal chemical composition of: 55% copper and 45% nickel as well as small amounts of very important manganese, cobalt, iron and other elements, although it's called constantan, but differs from that of nickel and chromium - Constantan and copper - Constantan constantan, so can't use EN and TN to replace. J type thermocouple measuring temperature area for - 200 ~ 1200 ℃, but usually use temperature range of 0 ~ 750 ℃. J type thermocouple has advantages of good linearity, thermoelectric emfs, high sensitivity, good stability and uniformity, the advantages of cheap, widely used by users. J type thermocouple can be used in the vacuum, oxidation, reduction and inert atmosphere, but iron anode oxidation at high temperature quickly, so the temperature is restricted, cannot be directly without reserve for curing atmosphere at high temperature. 1, platinum rhodium - 630 platinum thermocouple temperature measurement range. From 74 to 1064. 2, nickel chromium - 43 ℃ Nickel silicon thermocouple temperature measurement range 0 ~ 900 ℃, tungsten - 3 Rhenium thermocouple temperature range of 300 ~ 2000 ℃, nickel chromium - 4 Constantan thermocouple temperature measurement range 0 ~ 600 ℃, copper - 5 - constantan thermocouple temperature measurement range 200 ~ 100 ℃ S type thermocouple in the series of thermocouple with high accuracy, good stability, test your area wide, long using life, etc. Its physical and chemical performance is good, the thermoelectric potential stability and oxidation resistance at high temperature performance is good, suitable for oxidation and inert atmosphere. Because the S type thermocouple has excellent comprehensive performance, fit using the S type thermocouple temperature scale, for a long time as a scale interpolation instruments, 'ITS - 90 'is a rule in the future no longer check in as the scale of the instrument, but temperature advisory committee ( 有条件现金转移支付) That S type thermocouple can still be used for approximate complete international temperature scale. 1, thermocouple, detection (2 Temperature measurement) Component thermocouple is one of the industry commonly used temperature detecting element. Must go together with secondary instrument, its advantage is: 3, 1) measuring accuracy is high. Because of thermocouple direct contact with the object being measured, not affected by intermediate medium. 4, (2) the 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) High, up to + 2800 ℃ ( Such as tungsten - Rhenium) 。 5, (3) 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. 6, 7 of J type thermocouple type selection, 2 according to the temperature measurement range and accuracy, the corresponding index number 8, using temperature thermocouple in 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.