Jiangyin Chengxin Alloy Material Co., Ltd ，
Jiangsu Xiangcheng Supply Chain Management Co. LTD
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Fe-CuNi Type J Constantan Thermocouple Wire Trusted for Industrial Temperature Monitoring
Fe-CuNi (Type J) Constantan Thermocouple Wire is a thermocouple wire composed of Iron (Fe) as the positive leg and Copper-Nickel (CuNi), or Constantan, as the negative leg. Known as Type J thermocouple wire, it is widely used for temperature measurements in environments ranging from -210°C to 760°C, making it suitable for general-purpose industrial applications that don’t exceed this temperature limit.
Type J thermocouples provide good sensitivity (approximately 55 µV/°C) and are known for their fast response times, making them reliable for temperature monitoring and control in low- to moderate-temperature environments. However, they are not recommended for high-temperature applications above 760°C, as the iron wire can oxidize, affecting accuracy.
The Fe-CuNi thermocouple wire is commonly used in industrial applications, including heat treatment, plastic extrusion, and automotive testing, where consistent temperature control is required. Additionally, it is suitable for use in reducing or inert atmospheres due to its iron component, which performs well in these environments. Overall, Fe-CuNi (Type J) thermocouple wire is valued for its accuracy, stability, and cost-effectiveness, particularly in moderate-temperature industrial processes.
color codes of thermocouple ( J type )
The operating temperature range of type J thermocouple is -210~1200℃ , but it is usually used in the temperature range 0~750℃ due to embrittlement of Iron.
Type J thermocouple has good resistance to oxidation and high EMF output against Platinum 67, with good temperature accuracy, sensitivity and stability. It is recommended for vacuum, oxidizing, reducing or inert atmospheres, but it can not be used in sulphurous atmosphere above 500℃ .
| Name | JP | JN |
| Melting Range(℃) | 1402 | 1220 |
| Density(g/cm³) | 7.8 | 8.8 |
| Resistivity(μΩm20℃) | 12 | 49 |
| Resistance-temperture coefficient ×10-4/K(0℃-1200℃) | 95 | 0.5 |
| Tensile strength Rm N/mm² MPa | ≥240 | ≥390 |
| Elongation % | ≥20 | ≥25 |
Thermocouple temperature range and tolerance
Name | Usag Classification | Grade | Max. operating temperature(℃) | emperitre nres) | Tnlerene | Standard | |
Lang term | Short term | ||||||
Fe-CuNi (Type J) thermocouple bright wire | J | l | 600 | 750 | -40~750 | ±1.5℃ or ±0.4%t | GB/T4994 ISO 14125 |
| Ⅱ | -40~750 | ±2.5℃ or ±0.75%t | |||||
Some Key Features Fe-CuNi (Type J) Constantan Thermocouple Wire include:
Applications:
Widely used for temperature measurement and control in industrial furnaces, ovens, and kilns where temperatures stay within the medium range.
Employed in food production and processing equipment, such as ovens, cookers, and pasteurizers, for accurate temperature control and monitoring to ensure food safety and quality.
Common in plastic extrusion, injection molding, and rubber processing machines, where precise temperature control is essential for quality and consistency in finished products.
Used in reactors, mixers, and other equipment in the chemical industry to monitor and maintain controlled temperatures during various chemical reactions.
Utilized in heating, ventilation, and air conditioning systems for temperature monitoring, particularly in air handling units and ventilation ducts.
Frequently used in research labs for experiments involving controlled temperatures, as well as in calibration settings where medium-temperature accuracy is needed.
Applied in sterilizers, autoclaves, and incubators to ensure that medical and laboratory equipment operates at precise temperatures.
Employed in automotive engine testing and exhaust temperature monitoring to ensure engines operate efficiently and safely within designated temperature ranges.
Used for monitoring medium-range temperatures in refining processes, as well as in equipment like boilers and heat exchangers.
Applied across various manufacturing industries for monitoring and controlling machine temperatures, ensuring the safe and efficient operation of equipment.
Fe-CuNi (Type J) thermocouple wire is widely valued in these industries for its cost-effectiveness, reliability, and compatibility with medium-temperature applications.