What is a Thermocouple?
Thermocouples are sensors used to measure temperature. A thermocouple consists of two legs made of different metals. The ends of the wire legs are soldered together to form a connection point. This junction is where the temperature is measured. When the junction temperature changes, a voltage is generated. The voltage can then be interpreted and the temperature calculated.
Are there different types of thermocouples?
There are many types of thermocouples, each with different characteristics in terms of temperature range, durability, vibration resistance, chemical resistance, and application compatibility. Type J K, T "base metal" thermocouples are common thermocouples. Type R and Type S thermocouples are "rare metal" thermocouples used in high temperature applications
Where are thermocouples used?
Thermocouples are used in many industrial, scientific applications. They can be found in virtually all industrial markets: power generation, mining, oil/gas, pharmaceuticals, biotechnology, cement, paper, glass, and many more. Thermocouples are also used in everyday appliances such as stoves, furnaces, kilns, and pizza ovens.
Thermocouples are often chosen for their low cost, high temperature limit, wide temperature range, and durability.
So, when was the thermocouple created? ( History of Thermocouples)
As early as 1821, German physicist Thomas Johann Seebeck explored the concept of bonding different metals together. He found that observing a temperature change between the joint and the magnetic field – this is known as the Seeback effect.
From there, it was later discovered that the magnetic field is part of the thermal current. Voltages generated from two types of wires are used to measure temperatures from very high to very low.
The threshold for temperature measurement depends on the type of wire material used, and although the current is small, power can be generated from the thermocouple junction.
Scientists Michael Faraday and Georg Ohm conducted experiments using the Seeback effect to help further understand the impact and temperature measurement.
From this discovery, and after further research by scientists throughout history, thermocouples were manufactured in the early 1900's. Since then, the technology has grown and evolved to where it is today. They are now used in many different devices from food preparation to pharmaceutical production.
Manufacturing of Thermocouples
Since the discovery of temperature measurement, the fabrication of devices has been simple but effective. Two metal alloys bond together to form a knot.
The part of the junction is placed on the source where the temperature needs to be measured. The second point of the junction is maintained at a constant temperature source.
The temperature range depends on the type of metal used in the manufacture of the thermocouple. Nickel and nickel have a temperature range of -50 to 1,410 degrees, while and and measure temperatures from 0 to 2,315 degrees.
Thermocouples are simple in construction and manufacturers assemble thermometers from this pair of wires. A protective layer of insulating tubing usually covers these wires.
The thermocouple manufacturer determines the combination of metals and calibration used for assembly. The use of thermocouples depends on the environment. There are different diameters and materials to consider when making a particular type of thermocouple.
In other cases, fitting thermocouples to existing systems may change the way manufacturers design equipment.
Types of Thermocouples
A variety of thermocouples are manufactured using various metals for different purposes.
Various popular thermocouple types include:
Type K: Common thermocouple type, inexpensive, reliable and accurate
Type J: Also common, but has a narrower temperature range than Type K and has a shorter lifespan at higher temperatures
Type T: stable thermocouple for lower temperatures
Type E: stronger signal and higher accuracy
Type N: Same accuracy and limits as K, but slightly more expensive
Type S: suitable for high temperature, mainly used in the pharmaceutical industry
Type R: Similar in performance to Type S, often used at lower temperatures due to its accuracy and stability
Type B: has the highest temperature range of all thermocouples
Different types of thermocouples are grouped together, including industrial, general purpose, and multipoint.
Industrial thermocouples are a popular type. Manufacturers offer these thermocouples ranging from "IS A – M". General purpose thermocouples are suitable for most applications and are inexpensive. A commonly used general purpose thermocouple is TypeK.
Finally, multipoint thermocouples are an accurate form of temperature measurement. They are used where proper measurement and management of temperature is of paramount importance. They are manufactured as E, K, J, N and T types, made of different materials.
Final Thoughts on Making Thermocouples
Thermocouples are manufactured in a range and depend on the different needs of temperature measurement. From low to high, a variety of metals and materials can be used to form the correct type of thermocouple to maintain any temperature.
When it comes to choosing the right option, it's all about research and your manufacturing knowledge. The importance of the correct temperature for any element in the manufacture of all temperature-dependent products cannot be overemphasized.
