Thermocouple whether there are several _ instrument

Nickel chromium silicon - Magnesium nickel silicon thermocouple, N type thermocouple) For inexpensive metal thermocouple, it is a kind of standardization of thermocouple. The positive (a chemical composition: NP) Chemical composition as follows: in the name of the Ni, Cr, Si material 84. 4:14. 2-1. 4, the cathode ( NN) In the name of the chemical composition is: Ni: Si: 95 Mg material. Five. 4-0. 1, its use temperature range for - 20~1300℃。 2, technology: N type thermocouple thermoelectric emfs is larger, higher sensitivity, better stability and uniformity, oxidation resistance is strong, is not affected by short-range ordering etc, and its comprehensive performance is better than that of K type thermocouple. N type thermocouple cannot be directly used for sulfur, reducing or at high temperature reduction, oxidation atmosphere and vacuum alternately, is not recommended for people with weak oxidizing atmosphere. Nickel chromium silicon - Magnesium nickel silicon thermocouple, N type thermocouple) For inexpensive metal thermocouple, it is a kind of standardization of the thermocouple, the anode ( NP) Chemical composition as follows: in the name of the Ni, Cr, Si material 84. 4:14. 2-1. 4, the cathode ( NN) In the name of the chemical composition is: Ni: Si: 95 Mg material. Five. 4-0. 1, its use temperature range for - 20~1300℃。 Three characteristics: N type thermocouple thermoelectric emfs is larger, higher sensitivity, better stability and uniformity, oxidation resistance is strong, is not affected by short-range ordering etc, and its comprehensive performance is better than that of K type thermocouple. N type thermocouple cannot be directly used for sulfur, reducing or at high temperature reduction, oxidation atmosphere and vacuum alternately, is not recommended for people with weak oxidizing atmosphere. Four, performance: inexpensive metal thermocouple alloy with high thermoelectric potential, temperature and thermoelectric potential relationship is linear, thermoelectric potential long-term stability is good wait for a characteristic, conforms to the electrotechnical commission ( IEC) The corresponding standards. Main use is widely used in scientific research, metallurgy, chemical, electrical, instrumentation and other departments as temperature measuring device. Name of thermocouple temperature measurement range and tolerance model highest use temperature range ( ℃) Allowable deviation ( ℃) Long-term level of short-term temperature range and tolerance nickel chrome - Nickel GB/T2614K12001300I - silicon 40~1100±1. 5 ℃ or + 0. t 2 - 4% 40~1300±2. 5 ℃ or + 0. T nickel chromium silicon - 75% GB/T17615N12001300I - nickel silicon and magnesium 40~1100±1. 5 ℃ or + 0. t 2 - 4% 40~1300±2. 5 ℃ or + 0. 75% t used high temperature range refers to the following specifications: K, N type: 3. 2mm。 K type thermocouple has the following disadvantages 1, high temperature stability of thermoelectric emf the N type thermocouple and precious metals differential thermocouple. Under the high temperature, often due to oxidation damage. In the oxidizing atmosphere, 3 in diameter. 2 mm K type thermocouple, at 1100 ℃, 1200 ℃ under the 650 h, more than 0. The class of 75 permissible error; But N type thermocouple in the same conditions, after 1000 h, the thermoelectric emfs big change for 96. 6μV( 2. 6℃) 。 After 1000 h under 1250 ℃ still poor. 2, within the range of 250 ~ 550 ℃ short term thermal cycling stability is bad, even if, at the same temperature point in the process of rise to cool the thermoelectric emfs value is different also, the difference of 2 ~ 5 ℃. 3, K type thermocouple cathode, to occur within the range 150 ~ 200 ℃ magnetic transformation, left at room temperature to 230 ℃ range, dividing value often deviates from the indexing table, especially when used in the magnetic field, long a thermoelectric emf interference has nothing to do with the time. 4, chronically high flux neutron irradiation environment, due to the negative of Mn, Co and other element transformation, make its stability is poor, great changes have taken place in thermoelectric emfs.