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Flexibility And Usefulness Of Thermocouples As Sensors Explained
Jul 01,2021
There are a variety of sensors such as RTDs and thermocouples that are used for thermal control and temperature measurement across industries. Maintaining a certain temperature range is crucial for many processes due to the sensitivity of the materials used or the mere normal functioning of the process. These sensors may be used as independent probes or can be integrated within an existing system. While there are sensors that are designed to withstand and sense extremely high temperatures but with a wider range, there are a few others which offer extremely accurate output with tight tolerances. The thermocouple sensors are widely used because they meet most of these criteria. This post focuses on thermocouple sensors as a suitable solution for temperature management in industrial processes.

What Are Thermocouple Sensors and How Do They Work?
Thermocouples, just like any other temperature sensor, measure temperature and sense thermal changes. They are comprised of two dissimilar metals that are joined at two junctions, known as the hot and cold junctions. As the temperature around the thermocouple changes a potential difference or voltage is produced. This voltage is directly proportional to the temperature. So, as the temperature increases, the voltage also increases. Due to this relationship, thermocouples can sense the change in voltage and relate it to a temperature. The design of a thermocouple varies depending upon the system requirements; for instance, some may be wired, some may need joints, or connectors, and so on. Here, the right choice of metals is crucial as they will directly affect the readings of the thermocouple. These choices should be made according to your application requirements, the level of accuracy you require, and other factors.

Thermocouple Sensors, Their Types, and Quick Tips for Selection
Depending upon the metals used to make the thermocouple wires, its capacity, and calibration, thermocouples can be categorized into various types. Here are some pointers regarding the types and related information:

• Types E, J, K, N, and T refer to the use of base metals.
• C, R, and S types of thermocouples refer to the use of noble metals.
• The calibration depends upon the type of metal used, and it is set according to the required temperature range as well as external environmental parameters.
• Wires with a thicker diameter can better utilize the optimum temperature range.
• When choosing a thermocouple, aside from the temperature range you also need to consider its resistance to chemicals, vibration, abrasion, and so on.
• Ensure its compatibility with the existing system and equipment.

Benefits of Using Thermocouple Sensors
There are many benefits of using these sensors in your application.

• First, they offer accurate output for most processes and can measure a wide range of
• They are cost effective and simple to use, especially as probes.
• They are robust yet flexible and can be easily customized.
• They find applications in some of the most complex and mission critical applications such as gas turbines, heating systems, electric furnaces, diesel engines, and so on.
• Thermocouples can be designed as surface mount temperature sensors, which facilitates accurate output as the sensor is in close contact with the surface of the object which needs temperature control.
• It is suitable for surfaces of all types irrespective of rigidity, shape, or size.

If you plan to integrate thermocouples into your system or use them as independent probes, you must figure out the type that would best suit your applications. You can talk to known and certified thermocouple sensor manufacturers and suppliers., but ensure they know and understand your requirements well, and offer the required customizations. Instronline offers various types of thermal probes such as thermocouples, RTDs, and so on, and integrated systems for process-related temperature monitoring which are applicable across industries, and can be customized to suit your requirements.