Type J Thermocouple Wire

Type J thermocouple wire (Iron vs. Constantan) is suitable for vacuum, oxidizing, inert, and reducing environments. However, the iron component oxidizes rapidly above 538°C, which can affect performance. For high-temperature applications, using a thicker gauge wire is recommended to extend service life.

Chemical properties (%)
Material Chemical composition (%)
Ni Cu Si Iron Al
JP(Iron)       100  
JN(Constantan) 45 55      
Physical and mechanical properties
Material Density (g/cm3) Melting point (℃) Tensile strength (Mpa) Volume resistivity (μΩNaN) Elongation rate (%)
JP(Iron) 7.8 1402 >240 12.0(20℃) >20
JN(Constantan) 8.8 1220 >390 49.0(20℃) >25
EMF value range at different temperatures
Material EMF value (μV)
100℃ 200℃ 300℃ 400℃ 500℃ 600℃
JP-JN 5187~ 5351 10696~ 10862 16244~ 16410 21760~ 21936 27281~ 27505 32962~ 33242
EMF value Vs Pt(μV)
700℃ 750℃ 760℃ 800℃ 900℃ 1000℃
38958~39306 42089~ 42473 42725~ 43113      
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