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: Troubleshooting for thermocouple terminal
According to temperature measurement principles of thermocouple, we can know that thermal electromotive force includes two parts, contact potential and temperature difference potential. If contact between field terminal and extension wire of thermocouple, and extension wire and secondary instrument of the control room is not favorable, there will be additional contact potential in the signal transmitting process of thermocouple, and thus causing errors of temperature measurement. If wiring connection is not favorable, there will be sharp jump of temperature measurement. At this time, field reconnection will eliminate the fault of extension wire.
If there are connectors in the middle of extension wire, the influence of contact potential on temperature measurement will come, thus it will be better if there are no plugs in the usage of extension wire. If plugs cannot be avoided, it is necessary to mark position of connectors besides connecting treatment. Once there is temperature measurement fault, find out the position of connectors of extension wire; otherwise, faults caused by extension wire are hard to be eliminated.