The Difference Between Thermopiles and Thermocouples

Thermocouples and thermopiles are both common options, capable of producing electricity when they conduct temperature readings. Despite sharing a similar role and being found in many of the same applications, it is important that technicians do not confuse the two devices with one another. In this blog, we will provide a brief overview of the thermocouple and thermopile, allowing you to better understand each device and the role it plays in temperature detection.

Thermocouple devices are an essential temperature measurement element for many applications, often serving a safety role in preventing gas valves from transporting gas to burners when there is no flame present. Thermocouples are most often implemented within pilot appliances, thus they are regularly present within furnaces, unit heaters, water heaters, and other similar devices.

For their construction, a typical thermocouple will consist of two dissimilar electrical wires that are paired together to form an electrical junction. This establishes two electrical connections, those being a hot junction for measurement and a cold junction for reference. As the two junctions exhibit different temperatures, a DC voltage will be generated. With the use of the thermocouple’s reading equipment, the produced voltage can then be converted into a temperature reading for use. 

Depending on the application in question, thermocouples can play various roles. Oftentimes, the thermocouple is simply an instrument-connected temperature sensor, capable of providing readings for different applications. In other instances, the thermocouple may be relied on for temperature control and correction. When performing such tasks, the thermocouple will typically exhibit less accuracy and will require a millivolt-to-temperature conversion. With their capabilities, endurance, and low manufacturing costs, thermocouple devices are regularly implemented within industrial applications.

A thermopile, otherwise known as a power pile, is simply a sequence of thermocouples that allows for more millivolts to be produced. With their improved sensitivity over their counterpart, thermopiles are able to detect very small variations in temperature degrees. For their construction, antimony and bismuth bars are connected together with an astatic galvanometer. With the galvanometer, extreme sensitivity for produced electric current is achieved, allowing even the smallest degree changes within the bars to be detected with ease. While antimony and bismuth bars are the most common options for such devices, various other metals with differing heat conduction capabilities may be used. 

While thermocouples and thermopiles both are capable of measuring temperatures, the method in which they do so is what sets the two devices apart. Thermocouples are thermoelectric instruments, utilizing their dissimilar metals to produce a voltage that is proportional to the temperature difference between each junction. With a thermopile, a series of thermocouples are used to measure small amounts of radiant heat, allowing them to create a higher voltage output. If you are in need of a particular temperature sensing device and require top-quality parts that you can trust, look no further than ASAP AOG.

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