As a temperature sensor, thermocouple assembly is usually used with display instruments, recording instruments and signal conditioners.
Specification:
1. Thermocouple temperature range chart
Category | Type of sensing element | Relationship between wire diameter and temperature |
Thermo wire diameter (mm) | Long-term temperature (℃) | Short-tem temperature (℃) |
Platinum Rhodium 30 - Platinum Rhodium 6 | B type | Φ0.5 | 1600 | 1800 |
Platinum Rhodium 13 - Platinum | R type | Φ0.5 | 1300 | 1600 |
Platinum Rhodium 10 - Platinum | S type | Φ0.5 | 1300 | 1600 |
Nickel chromium silicon - Nickel silicon magnesium | N type | Φ0.3 | 700 | 800 |
Φ0.5 | 800 | 900 |
Φ0.8, Φ1.0 | 900 | 1000 |
Φ1.2, Φ1.6 | 1000 | 1100 |
Φ2.0, Φ2.5 | 1100 | 1200 |
Φ3.2 | 1200 | 1300 |
Nickel chromium - Nickel silicon | K type | Φ0.3 | 700 | 800 |
Φ0.5 | 800 | 900 |
Φ0.8, Φ1.0 | 900 | 1000 |
Φ1.2, Φ1.6 | 1000 | 1100 |
Φ2.0, Φ2.5 | 1100 | 1200 |
Φ3.2 | 1200 | 1300 |
Nickel chromium - Copper nickel | E type | Φ0.3 | 350 | 450 |
Φ0.5 | 450 | 550 |
Φ0.8, Φ1.0 | 550 | 650 |
Φ1.2, Φ1.6 | 650 | 750 |
Φ2.0, Φ2.5 | 750 | 900 |
Iron - Constantan | J type | Φ0.3, Φ0.5 | 300 | 400 |
Φ0.8, Φ1.0 | 400 | 500 |
Φ1.2, Φ1.6 | 500 | 600 |
Φ2.0, Φ2.5 | 600 | 750 |
Copper - Copper nickel | T type | Φ0.2 | 150 | 200 |
Φ0.3, Φ0.5 | 200 | 250 |
Φ1.0 | 250 | 300 |
Φ1.6 | 350 | 400 |
2. Thermowell application temperature range chart
Thermowell material | Long-term temperature | Short-term temperature |
Corundum CT1 | 1600 | 1800 |
High alumina CT2 | 1300 | 1600 |
Nickel base wrought superalloys 3YC52 | 1300 | 1350 |
Nickel base wrought superalloys GH3039 | 1250 | 1320 |
Nickel base superalloys GH3030 | 1200 | 1250 |
Heat resistant stainless steel 2Cr25Ni20 | 1200 | 1250 |
Silicon carbide | 1100 | 1150 |
Stainless steel 316L | 900 | 950 |
Stainless steel 1Cr18Ni9Ti | 800 | 900 |
3. Thermowell installing form (unit: mm)

4. Selection chart
Total length of thermowell (L or L*L1) | Branch number | Thermowell installing form | Protection head form | Diameter and material of thermowell |
300~2150mm (for I1, I2, I3, I4); 500*500mm, 750*500mm, 750*750mm (for I5); 225~450mm (for I6) | B1: Single branch; B2: Double branch | I0: No thermowell; I1: No fixed device; I2: Fixing thread; I3: Movable flange; I4: Fixed flange; I5: Rectangular movable flange; I6: Taper thermowell and fixing thread | C1: No protection head; C2: All stainless steel protection head; C3: Waterproof protection head; C4: Explosion-proof protection head | D0: Φ16mm; D1: Φ25mm, double-deck; D2: Φ16mm high quality aluminum; D3: Φ20mm high quality aluminum |
5. Thermocouple assembly installation diagram

Tips: Thermowell of thermocouple
To extend service life of thermocouple and protect it from chemical and mechanical damages, thermode (including insulating bush) is generally enclosed within thermowell so as to protect, fasten and support thermode. Materials which are used for thermowell should have favorable gas tightness to prevent external medium from permeating into the thermowell. With enough mechanical strength, it can resist bending and pressure; it has physical and chemical properties are stable, thus it will not corrode thermode. Moreover, in environment of high temperature, it has favorable property of high temperature resistance and anti-seismic property. And selection of thermowell generally depends on temperature measurement range, length of the heating zone, environmental atmosphere and lagging requirements of temperature measurement.
K type thermocouple assembles with protection head and stainless steel thermowell, with high pressure resistant, fast thermal response time and long operating life. Its thermo wire diameter is Ф2.5mm. K type thermocouple can directly measure the temperature of liquid, vapor, gas medium and solid surface in the range of 0~1000 ℃ in various production processes.