How to distinguish between thermocouples are negative _ instrument

Nickel chrome - Thermocouple nickel chrome - nickel silicon The related parameters in the nickel silicon thermocouple: nickel chrome - Nickel silicon thermocouple ( K type thermocouple) Is above 500 ℃ temperature zone dosage is very inexpensive metal thermocouple, its usage is the sum of other metal thermocouple. The anode ( KP) In the name of the chemical composition is: Ni: Cr material 90:10, the cathode ( KN) The chemical composition is: Ni: Si material 97: its use temperature range for - 20 ~ 1100 ( 1300). ℃. K type thermocouple has good linearity, large thermoelectric emfs, high sensitivity, good stability and uniformity and oxidation resistance is strong, and the advantages of cheap, can be used for oxidizing, inert atmosphere. K type thermocouple cannot be directly used for sulfur, reducing or at high temperature reduction, oxidation atmosphere and vacuum alternately, is also not recommended for people with weak oxidizing atmosphere. Nickel chrome - The chemical composition of a nickel and silicon thermocouple: nickel chrome - Nickel silicon ( Nickel aluminum) Thermocouple ( Index number is K) Is very nickel-chromium alloy (containing 10% chromium KP) , the negative is extremely containing silicon 3% nickel silicon alloy ( KN) 。 Its characteristic is, the use of wide temperature range and high temperature performance is stable, the thermoelectric emfs approximate linear relationship with the temperature, low price, therefore, it is the amount a thermocouple, nickel chromium - Nickel silicon thermocouple, K type thermocouple for continuous use in oxidizing and inert atmosphere. Short-term use temperature is 1300 ℃, the long-term use of temperature is 1100 ℃. After choosing high quality K type thermocouple can be used as a standard, to dividing work with nickel and chromium - Such as nickel and silicon metal thermocouple. Add the thermocouple on the poles yttrium metal and magnesium, oxidation resistance can be further improved, high temperature can reach 1300 ℃. In order to give full play to the advantages of cheap metal prices cheaper, at the same temperature, it can be installed more than several thermocouple, using its high sensitivity and thermoelectric properties of approximate linear characteristic, achieve the purpose of accurate measurement, the K type thermocouple is strong oxidation resistance of inexpensive metal thermocouple. Not appropriate in a vacuum atmosphere, carbon, sulphur and alternating oxidation and reduction under the atmosphere of bare wire. When oxygen tension is low, nickel and chromium in the chrome will be the optimal oxidation ( Also known as green corrosion) , has brought great changes in the thermoelectric emfs. 但金属气体对其影响较些因此，多采用金属制热电偶保护管。 How to distinguish between the thermocouple is negative: first nickel chrome - Nickel silicon two root of thermocouple wire has obvious distinguish color, there is a green, one is gray, green is positive, if is the thermocouple wire, you can use a small magnetic materials, on the cathode surface, namely above which the root of the gray silk, if this is the cathode is attractive, now with nickel and chromium - A lot of nickel and silicon thermocouple scene. Based on this feature, use the magnet can be easily identified thermocouple is negative.