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
Thermowll 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: Protection head of thermocouple
Protection head of thermocouple is used to fasten connector and connect external wire so as to protect thermode from external corrosion and wires and connect binding post well. Moreover, it forms temperature-sensing element of thermocouple together with thermode, insulating bush and connector. It is generally made into universal parts to install in different thermowells and protection head. There are three kinds of protection heads: All stainless steel protection head, waterproof protection head and explosion-proof protection head.
S type thermocouple assembles with protection head and corundum thermowell, should use wooden case for packing. Its thermo wire diameter is Ф0.5mm. S type thermocouple has high accuracy and good stability, can directly measure the temperature of liquid, vapor, gas medium and solid surface in the range of 0~1200 ℃ in various production processes.