Question

T – type thermocouple is made of:
1. Iron - Constantan
2. Copper - Constantan
3. Platinum - Rhodium
4. Chromel - Alumel

Answer 1

Correct Answer - Option 2 : Copper - Constantan

Explanation:

Thermocouple: A thermocouple is a sensor used to measure temperature. Generally, temperature up to 1400° is measured through this device.

• It consists of two wire legs made from different metals.
• The wire's legs are welded together at one end, creating a junction.
• This junction is where the temperature is measured.
• When the junction experiences a change in temperature, a voltage is created.
• The voltage can then be interpreted using thermocouple reference tables to calculate the temperature.

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Types of Thermocouple:

1. Type K Thermocouple (Nickel-Chromium / Nickel-Alumel): The type K is the most common type of thermocouple. It’s inexpensive, accurate, reliable, and has a wide temperature range.

• Temperature Range: - 270 to 1260°C

 

2. ​​Type J Thermocouple (Iron/Constantan): The type J is also very common. It has a smaller temperature range and a shorter lifespan at higher temperatures than Type K. It is equivalent to the Type K in terms of expense and reliability.

• Temperature Range: - 210 to 760°C

 

3. Type T Thermocouple (Copper/Constantan): The Type T is a very stable thermocouple and is often used in extremely low-temperature applications such as cryogenics or ultra-low freezers.

• Temperature Range: - 270 to 370°C

 

4. Type E Thermocouple (Nickel-Chromium/Constantan): Type E has a stronger signal & higher accuracy than Type K or Type J at moderate temperature ranges of 1,000F and lower. See temperature chart (linked) for details

• Temperature Range: - 270 to 870°C

 

5.  Type N Thermocouple (Nicrosil / Nisil): The Type N shares the same accuracy and temperature limits as Type K. The type N is slightly more expensive.

• Temperature Range: ​​- 270 to 392°C

 

6. Type S Thermocouple (Platinum Rhodium - 10% / Platinum): The Type S is used in very high-temperature applications. It is commonly found in the BioTech and Pharmaceutical industries. It is sometimes used in lower temperature applications because of its high accuracy and stability.​

• ​Temperature Range: - 50 to 1480°C

 

7. ​Type R Thermocouple (Platinum Rhodium -13% / Platinum): The Type R is used in very high-temperature applications. It has a higher percentage of Rhodium than Type S, which makes it more expensive. The Type R is very similar to the Type S in terms of performance. It is sometimes used in lower temperature applications because of its high accuracy and stability

• Temperature Range: - 50 to 1480°C

 

8. Type B Thermocouple (Platinum Rhodium – 30% / Platinum Rhodium – 6%): The Type B thermocouple is used in extremely high-temperature applications. It has the highest temperature limit of all of the thermocouples listed above. It maintains a high level of accuracy and stability at very high temperatures.

• Temperature Range: 0 to 1700°C