Using Thermocouples in Temperature Measurement
What if you have to take the temperature of the boiling volcanic lava? Can you use a usual thermometer for that purpose? No, you can’t. The high temperature of the lava will damage the thermometer, so you need something robust to measure its temperature. The inventors have a solution for filling every gap, so thanks to them; now we have the Thermocouple. Because of the low-price, Thermocouples have become a very popular type of temperature sensors. Also, the instrument can measure a wide range of temperatures compared to the usual thermometers.
How does a thermocouple work?:
The principal of the Thermocouple is very simple, yet amazing. Two wires of dissimilar metals do the magic here. The two wires are joined at the both ends for a continuous circuit. A change in the temperature at any point of the joined wires produces a voltage. The voltage depends on the temperature difference and the metals used in the Thermocouple. Many types of Thermocouples are there, all having different metal combinations and temperature ranges.
The maximum temperature that the meter can measure depends on the diameter of the wires used. So, a very thin wired meter can’t record high temperatures. In other words, if you want to measure the temperature of volcanic lava; you need a one with thick wires with appropriate metals.
J, K, E, and T are the types of Thermocouples you can buy in the market. The temperature range of the J-type is from 0° to 750°C. The temperature range of the K-type is from -200° to 1250°C. The temperature range of the E-type is from -200° to 900°C. And the temperature range of the T-type is from -250° to 350°C. Due to the high-temperature range of the K-type, we call it the “general type” Thermocouple.
Choosing a Thermocouple:
So, now you understand the types of meters and about the temperature ranges. It depends on the industry you are working, and look for following criteria when buying the instrument.
* Temperature range.
* Chemical resistance.
* Vibration and abrasion resistance.
* Make sure it’s compatible with the equipment you have.
As you can see in the above picture, the insulated metal wires only open at the temperature sensing edge. Damaged wire insulation leads to false readings. Well, the insulation material depends on the temperature range of the Thermocouple (plastic or ceramic.) With time, the insulation can get damaged under general conditions and leads the meter to give false readings.
As I said earlier, Thermocouples can measure high temperatures up to 3000 °C. They let us know the temperatures in gas turbine exhaust, diesel engines, kilns, fog machines, and other industrial processes. It’s an essential instrument in the steel industry. Monitoring the temperature throughout steel making process is a must. So, a Thermocouple is the best option to measure the high temperatures incorporated in the steel/iron industry.
Well, it’s the 21 century, so now you can buy wireless Thermocouples that can transmit the data to your smartphone and the tab. Special meters are there in the market for measuring the temperatures of the flat surfaces. OK, let’s meet again with a similar useful article soon. Hope you enjoyed this article.