Thermocouples are often used to measure the temperature of liquid, steam and gaseous media and solid surface temperatures.


Thermocouples are commonly used temperature measuring components in temperature measuring instruments. It directly measures temperature and converts the temperature signal into a thermoelectromotive force signal. It is converted into the temperature of the measured medium by electrical instruments. Thermocouples are usually composed of main parts such as hot electrodes, insulating sleeve protection tubes and junction boxes. Usually used with display instruments, recording instruments and electronic regulators.

Sino-Inst offers a variety of  Thermocouples for Temperature measurement. If you have any questions, please contact our sales engineers.

Sheath Thermocouple

It is usually used along with display instruments, recording instr-uments, electronic computers and so on. It is able to directly me-asure the temperature of liquid, steam and gas and solid surfacein a variety of production processes within the range of 0 ~1300℃.

The electrode of sheath thermocouple are consisted by two different materials of conductor. When there is a temperature difference between the measuring end and the reference end. It will generate the thermal electric potential. The working instrument will show the corresponding temperature value of the thermal electric potential.

Range for temperature measurement and error-tolerance

Extended reading: LN2 tanks sensor

Assembled Sheathed Thermocouple

Product Applications

  • Cooling and heating systems
  • Water supply and water heating systems
  • Air-conditioning systems
  • Automation system temperature mensuration and control
  • Suited for temperature measurement in industrial environments, especially around motors, generators and other high voltage equipment.
  • Widely used in the injection molding mold.

Temperature measurement range and tolerance error

Explosion-proof Thermocouple

Explosion-proof thermocouple uses the principle of interval
explosion-proof with the junction box and other parts with enough strength where the dangerous parts which will generate spark, electric arc and dangerous temperature are sealed, so when the explosion occurs inside the cavity, the flame of the explosion can be cooled and distinguished in the gap between the joint surface so that the flame and the temperature will not be passed to the cavity.
Finally, the explosion-proof is realized.

Explosion-proof thermocouple Temperature measurement range

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Platinum Rhodium Thermocouple

The platinum rhodium thermocouple is a traditional temperature measuring element. It has stable thermoelectric performance and strong oxidation resistance, and is suitable for continuous use in an oxidizing and inert atmosphere. The long-term use temperature is 1600℃, and the short-term use temperature is 1800℃. The technical indicators are as follows:

  1. Temperature measurement range: 0~1800℃
  2. Temperature measurement accuracy: <± 0.5% t
  3. Time constant: ≤180s
  4. Insulation resistance: 5MΩ (at 20℃)
  5. Specification and size: 500, 750, 1000, 1200 (mm)
Product nameModelOuter sleeve materialRecommended maximum operating temperature
S-type platinum rhodium thermocouple
(Platinum Rhodium 10 platinum)
R-type platinum rhodium thermocouple
(platinum rhodium 13 platinum)
Type B platinum rhodium thermocouple
(Pt Rh 30-pt RH 6)
(double platinum rhodium)

K-type Thermocouple

The K-type thermocouple is used as a temperature sensor. The K-type thermocouple is usually used with display instruments, recording instruments and electronic regulators.

The K-type thermocouple can directly measure the surface temperature of liquid vapor, gaseous media and solids in various production ranges from 0℃ to 1300℃.

K-type thermocouple is the cheapest metal thermocouple with the largest consumption at present, and its consumption is the sum of other thermocouples.

  • The diameter of K-type thermocouple wire is generally 1.2mm~4.0mm.
  • The nominal chemical composition of the positive electrode (KP) is: Ni:Cr=90:10, the nominal chemical composition of the negative electrode (KN) is: Ni:Si=97:3, and its service temperature is -200℃~1300℃.
  • The K-type thermocouple has the advantages of good linearity, high thermoelectromotive force, high sensitivity, good stability and uniformity, strong oxidation resistance, and low price. It can be used in oxidizing inert atmosphere and widely used by users.
  • K-type thermocouples cannot be directly used in sulfur, reducing or reducing, oxidizing alternate atmospheres and vacuum at high temperatures, nor are they recommended for use in weakly oxidizing atmospheres.

Thermocouple Types

Commonly used thermocouples can be divided into two categories: standard thermocouples and non-standard thermocouples.

The so-called standard thermocouple refers to a thermocouple with a unified standard indexing table that specifies the relationship between the thermoelectric potential and the temperature, the allowable error, and the national standard. It has a matching display instrument for selection.
Non-standardized thermocouples are inferior to standardized thermocouples in use range or order of magnitude. Generally, there is no unified indexing table. It is mainly used for measurement in some special occasions.

Standardized thermocouples China started from January 1, 1988. Thermocouples and thermal resistances are all produced in accordance with IEC international standards. Seven standardized thermocouples of S, B, E, K, R, J, and T are designated as China’s unified design. Thermocouple.

In theory, any two different conductors (or semiconductors) can be made into thermocouples. However, as a practical temperature measuring element, there are many requirements for it.

In order to ensure the reliability in engineering technology and sufficient measurement accuracy. Not all materials can form a thermocouple. Generally, the basic requirements for the electrode material of a thermocouple are:

  1. In the temperature measurement range, the thermoelectric properties are stable. It does not change with time. It has sufficient physical and chemical stability and is not easy to be oxidized or corroded;
  2. Low temperature coefficient of resistance, high conductivity, low specific heat;
  3. The thermoelectric potential generated in temperature measurement should be large, and the relationship between thermoelectric potential and temperature is linear or close to linear single value function;
  4. Good reproducibility of materials. High mechanical strength, simple manufacturing process and low price.

Sino-Inst, Manufacuturer for Thermocouples, like: Armoured thermocouple, assembly thermocouple, explosion-proof thermocouple, etc.

Sino-Inst’s Thermocouples, made in China, Having good Quality, With better price. Our Temperature measurement instruments are widely used in China, India, Pakistan, US, and other countries.

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About KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects. Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.