Cartridge Heaters has been a reliable source of modern heating sensors and elements for a number of years. Here at Cartridge Heaters, we firmly believe that quality, flexibility and an attention to detail are all key components that should be addressed at all times. As this is a rather specific industry, it it a good idea to briefly examine the main purposes behind temperature sensors as well as how they function. There are a number of different variants and the thermocouples used will primarily depend upon the unique heating requirements. Let’s look at these concepts in a bit more detail.
Defining the Modern Temperature Sensor
The first concept to appreciate is that the terms “temperature sensor” and “thermocouple” can be used interchangeably. Their main purpose is to detect temperature variations within a closed system. This information can then be passed on to other mechanisms such as fans, compressors or a thermostat within the common household oven.
Thermocouples are comprised of two different types of metal wires and what is known as a junction point. As the temperature within a system changes, the metal wires will expand or contract at a different rate. This generates a small magnetic field at their mutual point of contact (the junction mentioned previously). This is also known as the Seebeck effect. Variations within this magnetic field can be used to determine a change in temperature. As individual metals will expand and contract at a uniform rate, it is possible to be provided with very exact readings. Such accuracy is an obvious concern when more complicated components need to be monitored during their operation.
Still, this is just the basic principle behind temperature sensors. There are a number of different variants on the market and each is intended to be used for a specific application. Let us now take a look at two of the most widely used sensing devices.
J Type Thermocouples
J-type thermocouples are also known as “iron-constantan” units. Many consider this variety to be more sensitive when compared to K-type units, as the temperature range is smaller and the lifespan at higher temperatures is likewise reduced. However, these are economical alternatives and they are highly reliable. This greater sensitivity is also a key advantage when used in extremely delicate electronic devices. As a rule of thumb, this thermocouple is able to measure temperatures ranging from -40ºC to +750ºC.
K Type Thermocouples
A K-type thermocouple is the most common utilised on the market today. Two alloys known as “chromel” and “alumel” are used in the construction of the wires. As this type was manufactured during an earlier stage of metallurgy, it is not as accurate as the previous version. It is able to measure temperatures ranging from -200ºC to +1,350ºC. Another benefit of this variant is that it can work quite well within oxidising atmospheres (such in the outdoors or a corrosive environment). So, K-type instruments enjoy a wide variety of domestic and industrial uses. One drawback is that the alloys employed within the wires are sensitive to the presence of hydrogen. Over time, this can cause both the unit and its accuracy levels to degrade.
Putting the Information Together
Of course, this is only a general overview of how a thermocouple functions and the two main types which are used within the modern world. Determining the exact variety will depend upon the intended use as well as the unique temperature requirements. If you are looking for reliable temperature sensors or should you have any additional questions revolving around how such units are installed, please feel free to contact us at your earliest convenience.