Thermocouples

Overview of different thermocouple types

Here you will find a comprehensive overview of different types of thermocouples and their areas of application. Thermocouples are essential sensors for temperature measurement that are characterised by their versatility and precision. They consist of two different metal wires that are connected at one end and generate a voltage that can be measured when the temperature changes. Choosing the right thermocouple depends on many factors, including the temperature range, the environment of use, the response time and the required accuracy.

Sheathed thermocouples

Sheathed thermocouples are specially developed sensors that are characterised by their robust design and high flexibility. These thermocouples consist of a flexible metal sheath that protects the actual sensor element. The sheath is usually made of materials such as stainless steel or Inconel, which offer high resistance to extreme temperatures and mechanical stresses. The inside of the sheath contains the thermocouple wires, which are insulated from each other by a highly compressed, mineral-insulated powder. This design allows the sheathed thermocouple to adapt to different shapes and positions without losing functionality.

In addition, sheathed thermocouples offer excellent resistance to vibrations and shocks, making them particularly suitable for use in harsh industrial environments. Their durability and reliability are guaranteed by the resistant materials and precise manufacturing technology. Another advantage of these thermocouples is their fast response time, which enables immediate temperature measurement. This makes them ideal for dynamic processes where continuous monitoring is required.

Areas of application for sheathed thermocouples

Sheathed thermocouples are used in a variety of industrial applications where high temperature resistance and mechanical strength are crucial. A typical area of application is metal processing, where they are used to monitor and control temperatures in melting furnaces and during heat treatment. Precise temperature measurement is crucial for the quality of the end product. Thanks to their robust properties, sheathed thermocouples can also be used in the extreme conditions of steel and iron production, where they have to withstand high temperatures and strong vibrations.

Mineral-insulated thermocouples are also widely used in the chemical industry. They are used in reactors, distillation columns and other processes where aggressive chemicals and high pressures prevail. The resistance of sheathed thermocouples to these conditions makes them a reliable choice for temperature monitoring in chemical production plants. They are also used in power generation, particularly in power plants, where they measure temperatures in turbines, boilers and other critical components. Their ability to work precisely and reliably under extreme conditions contributes to the efficiency and safety of operations.

Sheathed thermocouples are also used in the automotive industry. They are used to monitor temperatures in engines, exhaust systems and air conditioning systems. The ability to withstand high temperatures and vibrations, as well as easy integration into existing systems, make them an optimal solution for these applications.

Insulated tubular thermocouples

Insulated tubular thermocouples are special sensors that impress with their robust design and additional stability. They consist of a metal sheath that securely encases the inner sensor element and protects it from external influences. The sheath is usually made of high-strength materials such as stainless steel, which ensures high resistance to extreme temperatures, mechanical stress and aggressive chemicals.

Inside the sheath are two thermocouple wires that are insulated by a heat-conducting material. This design not only ensures high mechanical stability, but also excellent heat transfer from the outer sheath to the sensor element. A key advantage of sheathed tube thermocouples is their resistance to pressure and vibration, which makes them ideal for use in demanding industrial environments.

The design of these thermocouples also enables easy integration into existing systems. Thanks to their robust construction and high material quality, sheathed tube thermocouples offer a long service life and minimise maintenance requirements. Their fast response time and accuracy make them reliable instruments for temperature monitoring in sensitive processes.

Application areas of sheathed tube thermocouples

Mineral-insulated thermocouples are mainly used in extreme environments where high pressure and aggressive chemicals are present. A typical area of application is the chemical industry, where these thermocouples are used to monitor reactor temperatures, distillation processes and other processes involving corrosive substances and high pressures. Their resistance to chemical attack and mechanical stress makes them the ideal choice for such applications.

Another important field of application is the oil and gas industry. Here, jacketed tubular thermocouples are used in boreholes, pipelines and refineries, where they have to withstand extreme pressures and aggressive media. Their ability to measure precise temperatures under such conditions makes a decisive contribution to the safety and efficiency of processes.

Mineral-insulated thermocouples are also indispensable in power generation, especially in power stations. They are used to monitor temperatures in turbines, boilers and other critical components. Their robust design ensures that they can withstand the high temperatures and strong vibrations in these systems, thereby increasing operational safety and efficiency.

Screw-in thermocouples

Screw-in thermocouples are special temperature sensors that are equipped with a thread that enables simple and safe installation in various systems. This design ensures that the thermocouples sit firmly and stably in their place of use, which is particularly important in environments where vibrations and movements can occur. The thread can be designed differently depending on the area of application and specific requirements to ensure an optimum fit.

The construction of a screw-in thermocouple is typically made of robust materials such as stainless steel and Inconel, which offer high resistance to corrosion and extreme temperatures. Inside the sensor are two thermocouple wires that are connected at one end and generate a voltage that is measured when the temperature changes. This design enables a fast response time and high precision in temperature measurement.

Another advantage of screw-in thermocouples is their versatility. They can be manufactured in different lengths and diameters to meet the specific requirements of each application. They are also often available with different thermowells and housings to provide additional protection against mechanical influences and chemical substances.

Areas of application for screw-in thermocouples

Screw-in thermocouples are often used in machines and systems where simple and secure fastening is required. A typical area of application is heating systems, where precise monitoring and control of the temperature is crucial for the efficiency and safety of operation. Here, screw-in thermocouples are screwed into boilers, pipework and other components to ensure precise measurement of operating temperatures.

Screw-in thermocouples are also widely used in motors. They are used to monitor the motor temperature to prevent overheating and ensure optimum performance. The robust design of these thermocouples ensures that they can withstand the strong vibrations and high temperatures in the motor area.

Screw-in thermocouples are also indispensable in industrial processes. They are installed in production plants, reactors and pressurised vessels where reliable temperature monitoring is required. The simple installation and secure fit ensure continuous and precise measurement, which is essential for controlling and optimising processes.

Screw-in thermocouples are also used in the food industry, where they are used to monitor temperatures in cooking and freezing systems. Precise temperature control is crucial for the quality and safety of food products.

Surface thermocouples

Surface thermocouples are specialised temperature sensors that have been specially developed to precisely measure the temperature of surfaces. They are characterised by a flat design that enables direct and efficient heat transfer from the surface to be measured to the sensor element. These thermocouples consist of two different metal alloys that are connected at one end and generate an electrical voltage proportional to the temperature when the temperature changes.

The design of surface thermocouples often includes a flat sensing tip or plate that ensures close contact with the surface. This design minimises the influence of ambient temperatures and enables the surface temperature to be measured quickly and accurately. The materials from which these thermocouples are made offer high resistance to abrasion and corrosion, ensuring their longevity and reliability in industrial environments.

Another advantage of surface thermocouples is their versatility. They can be manufactured in different sizes and shapes to meet the specific requirements of each application. In addition, they are often equipped with adhesive or magnetic holders for easy mounting and dismounting.

Areas of application for surface thermocouples

Surface thermocouples are used in numerous industrial and commercial applications where monitoring the surface temperature is crucial. A typical area of application is in production technology, where they are used to monitor the temperatures of machine parts, conveyor belts and other surfaces. By accurately measuring surface temperatures, production processes can be optimised and the quality of the end products ensured.

Surface thermocouples are also widely used in air conditioning systems and HVAC applications (heating, ventilation and air conditioning). They are used to monitor the surface temperatures of heating and cooling systems to ensure efficient and even temperature distribution. This not only contributes to energy savings, but also improves the comfort and safety of building users.

Surface thermocouples also play an important role in the electronics industry. They are used to monitor the temperatures of circuit boards, processors and other sensitive components. Precise temperature control is crucial here to prevent overheating and maximise the service life and performance of electronic devices.

Surface thermocouples are also used in the food industry, where they are used to monitor the temperatures of cooking and cooling appliances. Precise temperature measurement is necessary here to ensure the safety and quality of the food.

Line thermocouples

Lead thermocouples are temperature sensors characterised by their extended sensor cables. These cables allow the measuring point to be positioned flexibly, even if it is far away from the evaluation electronics. The sensor cables are often insulated to minimise signal loss and interference from external influences. This is particularly important in environments with strong electromagnetic fields or extreme temperature conditions.

The design of a line thermocouple comprises two different metal wires that are connected at one end and generate a voltage when the temperature changes. These wires are extended by insulated cables that allow the sensor to be moved to different areas without compromising the accuracy of the measurement. The insulation can be made of different materials depending on the requirements of the specific application, such as glass fibre, PTFE or polyimide.
Another advantage of line thermocouples is their robustness and durability. They are designed to withstand extreme conditions, including high temperatures, humidity, chemicals and mechanical stress. Due to the flexible positioning of the sensor, they can be used in hard-to-reach or extensive areas where conventional thermocouples would be impractical.

Application areas of line thermocouples

Lead thermocouples are ideal for applications where the measuring point is far away or difficult to access. A typical area of application is large-scale production plants in which several temperature measuring points are distributed over large distances. Here, the extended sensor cables enable centralised monitoring and control of temperatures, which contributes to increased efficiency and quality control.

Line thermocouples also play an important role in environmental monitoring. They are used to monitor temperatures in various environments, such as water, soil and atmospheres. The long sensor cables make it possible to record the temperature at various measuring points and to collect and analyse the data centrally. This is crucial for analysing climate change and environmental pollution.

Line thermocouples are also widely used in the petrochemical and oil & gas industries. They are used to monitor temperatures in pipelines, tanks and boreholes, where extremely high or low temperatures can prevail. The robust design and reliable insulation ensure that the sensors work accurately under these extreme conditions.

In power generation, especially in power stations, line thermocouples are indispensable. They are used for temperature monitoring in boilers, turbines and cooling circuits. The flexible cables enable temperatures to be recorded precisely at critical points, which helps to optimise operating conditions and prevent failures.

Push-in thermocouples

Push-in thermocouples are specialised temperature sensors designed for direct measurement in liquids or gases. This type of thermocouple is characterised by its ease of use and versatility. A special feature is their brass housing, which ensures high thermal conductivity and robustness.

The design of a plug-in thermocouple comprises two different metal alloys that generate an electrical voltage when the temperature changes. The sensor element is housed in a cylindrical brass sleeve, which ensures optimum heat transfer. A major advantage of these thermocouples is that they are mounted in the base of the bore, which enables precise positioning.

Another important feature of the plug-in thermocouples is their adjustable installation depth. The depth can be flexibly adjusted using an integrated spring, which allows the sensor to be optimally positioned in the medium to be measured. This contributes significantly to the accuracy and reliability of the temperature measurement.

Areas of application for insertion thermocouples

Insertion thermocouples are most commonly used in injection moulding systems. In this industrial environment, precise and fast temperature measurements are crucial for the quality of the parts produced and the efficiency of the process. The robust brass sleeves of the insert thermocouples withstand the high temperatures and pressures that occur in injection moulding machines.

In injection moulding machines, these thermocouples are typically used to monitor the melting temperature of the plastic. They can be installed directly in the machine’s nozzles or barrels, where they continuously measure the temperature of the molten material. The ability to adjust the installation depth via the spring allows the sensor to be optimally positioned to obtain the most accurate measurements.

The use of insertion thermocouples in injection moulding systems contributes significantly to process optimisation. By precisely controlling the melting temperature, product quality and energy efficiency can be improved. In addition, the robust design of these thermocouples enables reliable continuous operation under the demanding conditions of plastics processing.

Piercing thermocouples

Piercing thermocouples are specially developed temperature sensors with a pointed probe. These probes were specially developed for the automotive industry to take temperature measurements in hoses, such as cooling water hoses. The unique design makes it possible to insert the sensor directly into the material without having to carry out extensive conversion work.

The construction of a piercing thermocouple is typically made of robust and corrosion-resistant materials that can withstand the demanding conditions in vehicles. The pointed probe allows easy penetration into hoses and other flexible materials, ensuring precise temperature measurement directly inside the medium.

A major advantage of piercing thermocouples is their quick and easy installation. After insertion, they can simply be fixed in place with a cable tie, enabling stable positioning without the need for time-consuming assembly work. This makes them particularly suitable for retrofitting or temporary measuring tasks in the automotive industry.

Areas of application for insertion thermocouples

Insertion thermocouples are mainly used in the automotive industry, particularly for temperature monitoring in cooling systems. They are often used to measure the cooling water temperature by inserting them directly into the cooling water hoses. This method enables precise temperature measurement without interfering with the existing cooling system.

In addition to cooling water hoses, insertion thermocouples can also be used in other flexible lines, such as fuel lines or oil hoses. This allows comprehensive temperature monitoring of various fluids in the vehicle, which is very important for optimising engine performance and efficiency.

Easy installation and fixing with cable ties makes insertion thermocouples particularly valuable for test runs and development processes in the automotive industry. They enable fast and flexible temperature measurements at various points in the vehicle without the need for complex modifications to the test object.

Sheathed thermocouples with connection head

Sheathed thermocouples with connection head are a special variant of sheathed thermocouples that are also equipped with a connection head. The connection head serves as an interface for easy connection and integration of the thermocouple into existing systems. This design combines the robust properties of a sheathed thermocouple with the practical handling and connection options of an industrial connector.

The sheath of such a thermocouple is made of a high-strength metal such as stainless steel or Inconel and protects the inner sensor element from external influences such as high temperatures, pressure and corrosive chemicals. Inside this sheath are two different thermocouple wires, which are insulated from each other by a compacted, mineral-insulated powder. This ensures high mechanical stability and excellent heat transfer.

The connection head, which is usually made of aluminium, enables a simple and secure connection to measuring devices, controllers or other evaluation systems. It is available in different versions to meet the specific requirements of each application. The connection head also offers protection against moisture, dust and other environmental influences, which increases the reliability and durability of the thermocouple.

Application areas of sheathed thermocouples with connection head

Sheathed thermocouples with connection head are particularly useful in industrial environments where a robust and reliable connection is crucial. A typical area of application is process control in the chemical and petrochemical industries. Here, these thermocouples are used to monitor and control temperatures in reactors, distillation columns and other process plants. The combination of high resistance to chemical attack and simple integration into control systems makes them ideal for these applications.

Mineral-insulated thermocouples with connection heads are also widely used in power generation. They are used in power stations to monitor the temperature of turbines, boilers and other critical components. The connection head enables a fast and secure connection to the monitoring systems, which increases the operational safety and efficiency of the systems.

These thermocouples are also indispensable in metal processing. They are used for temperature measurement in melting furnaces, foundries and during heat treatment. The robust design of the sheath and the simple connection via the connection head ensure precise and reliable measurements under extreme conditions.

Accessories for thermocouples

To ensure the proper operation and longevity of thermocouples, the right accessories are essential. Thermocouples are precise measuring instruments that are used in various industrial and commercial applications. The right accessories play a key role in ensuring measurement accuracy, extending sensor life and enabling efficient integration into existing systems. The most important accessories include extension cables, compression fittings and display units.

Important accessories at a glance

1. extension cables

Extension cables are crucial for connecting thermocouples to evaluation or control devices over long distances. These cables are made of special alloys that correspond to the materials of the thermocouple in order to transmit the thermal voltage correctly and minimise signal losses. High-quality extension cables also offer good insulation against electrical interference and mechanical stress. There are different types of extension cables that should be selected depending on the environment and application:

– Standard cable: For general applications in non-extreme environments.

– High temperature cables: For applications where the cables are exposed to high temperatures.

– Shielding cables: To minimise electromagnetic interference and improve signal quality.

2. compression fittings

Compression fittings are important accessories that ensure a secure and tight connection between the thermocouple and the process connection. They allow easy mounting and dismounting of the thermocouple and ensure that the sensor is correctly positioned and fixed. Compression fittings are available in different materials and sizes to meet the specific requirements of different applications. Some important features of compression fittings are

– Pressure resistance: For applications with high process pressure.

– Chemical resistance: For use in aggressive media.

– Temperature resistance: For high temperature applications.

3. indicating devices

Indicators are essential for visualising and evaluating the temperatures measured by thermocouples. They convert the voltage generated by the thermocouple into easily readable temperature values. Modern display units often offer additional functions such as data storage, alarm functions and interfaces for connection to higher-level control systems. The following aspects should be taken into account when selecting display devices:

– Display accuracy: For precise temperature measurements.

– Ease of use: For simple configuration and operation.

– Compatibility: With various thermocouple types and connection options.

Choosing the right accessories

Selecting the right accessories depends on the specific requirements of your application. Here are some factors that should be considered:

– Environmental conditions: High temperatures, chemical influences and mechanical loads require special accessories.

– Accuracy requirements: Applications that require high measurement accuracy benefit from high-quality extension cables and precise indicators.

– Duration of use: Durability and reliability of accessories are crucial for applications where continuous operation is required.