Electric hot thermocouple will grows with the temperature measuring end, it is only with the size of the thermocouple temperature at the ends of the materials and relevant, has nothing to do with the hot electrode length and diameter.

the appearance of all kinds of thermocouple is often due to the need to vary, but their basic structure is roughly same, usually by the hot electrode, insulation sleeve to protect the main parts such as pipe and connection box.

to introduce below J type thermocouple and K type thermocouple:

- J type thermocouple is also called 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. Iron - Constantan 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 is larger, higher sensitivity, stability and uniformity is good, 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 K type thermocouple used in curing atmosphere at high temperature as a kind of temperature sensor, K type thermocouple and display instrument, usually record instrument and electronic regulator. K type thermocouple can be directly measured various production from 0 ℃ to 1300 ℃ in the range of the surface temperature of the steam and gas medium of liquid and solid.

K type thermocouple features:

(1) high accuracy of measurement. Because of thermocouple direct contact with the object being measured, not affected by intermediate medium.

2. Wide measuring range. The commonly used thermocouple from - 50 ~ + 1600 ℃ can be continuous measurement, some special thermocouple minimum measurable to - 269℃（ Such as gold iron nickel chrome) , up to + 2800 ℃ ( Such as tungsten - Rhenium) 。

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.