When it comes to temperature sensors used in industrial furnaces, there are no one-size-fits-all solutions. The right sensor must be selected depending on the application and the anticipated budget. The three most common types of temperature probes used in heating equipment are:
thermocouples
resistance temperature detectors (burns RTDs)
thermistors
Thermocouples are measuring devices that determine temperature based on differences in the voltage created by two conductors, made of different metals, connected at the end.
These thermoelectric sensors are often used to measure the temperature inside furnaces and boilers, due to their accuracy and versatility and wide temperature range.
K-type thermocouples, consisting of nickel combined with alumel or chromium, are very popular temperature sensors for furnaces. This is influenced by their relatively low price and their ability to be used over a wide temperature range, even from -200 to 1250°C.
High oven temperatures are also well tolerated by L, J, S, B and N type thermocouples.
When using thermocouples, suitable thermowells must not be forgotten. Temperature shocks and destructive properties of the medium under test, such as corrosive vapours, have a bad effect on the delicate wires. In order to prevent this, we recommend the use of thermowells made of, among other things, ceramic or corrosion-resistant steel.
RTD temperature sensors operate on the principle that the resistance (resistivity) of the metal from which the conductors are made changes under the influence of the temperature being measured.
The temperature dependence of the resistance of some metals is repeatable and relatively linear, making RTD sensors highly desirable for applications requiring a high level of accuracy. Like thermocouples, these sensors can detect a wide temperature range. These features make them a very good choice for industrial furnaces.
Choosing the right temperature sensors for a particular furnace application can lead to significant savings and increased process efficiency, including reduced system uptime. Simply put, when the furnace system has better data, it will be able to make better decisions. In addition, the right temperature sensor can help:
detect potential hot spots, faults, leaks and temperature imbalances
increase the quality of the end product
reduce fuel costs
reduce electricity costs
The highest quality of industrial furnace operation can only be achieved if not only the measuring sensors, but also the regulation of the measured parameters, are highly accurate.
Precise temperature curves are indispensable in complex processes, which include, for example, the firing and annealing of various materials. This objective, in both through- and batch-fired furnaces and irrespective of the type of heating, is effectively met by PID controllers.
They enable:
accurate depiction of firing curves and display of process screens
recording and analysing of measurement data for each batch
communication via fieldbus interfaces using the JUMO visualisation software.
PID controllers, such as the JUMO ditraTRON and dTRON , are recommended for less complex processes. These units have modules prepared by us that you can use for your heating process.
Manufacturers of industrial furnaces for the aerospace and automotive industries will find JUMO equipment compliant with the requirements of the AMS2750/ CQI-9 directives. On request, components can be supplied with a certificate of conformity.
PID controllers may not be sufficient for more complex processes, e.g. when the furnace has two zones or multiple measuring points. In such cases, we recommend the JUMO variTRON 500 PLC controller, which allows you to create any programme individually tailored to your process in the Codesys programming environment.
In combination with monitoring control and process management software, these controllers offer almost unlimited possibilities for automation.
JUMO offers for industrial furnace manufacturers
JUMO offers the complete equipment needed to build and operate a furnace, from sensors and safety temperature limiters, to control devices and automation systems. In addition, we offer test and SAT and TUS test equipment to meet the requirements of AMS2750 and CQI-9. Contact us and equip your furnace with reliable and versatile components!