During the 1960s, a significant advance in infrared temperature measuring came about with the introduction of ratio or two-colour infrared thermometry.
This technology uses two infrared sensors within the transmitter, each sensor being sensitive to a specific and different infrared wavelength. The output from the sensors is fed into a microprocessor where an energy 'ratio' is calculated by dividing one sensor signal by the other.
Standard or single-colour infrared thermometers are greatly affected if the IR energy is obscured or attenuated, because they rely for accuracy on the total amount of infrared energy emitted from the product reaching the sensor. In the case of molten metals, specifically irons and steels, the emitted infrared energy tends to be nonlinear and changes with temperature and wavelength, thus making standard thermometers inaccurate for these applications.
Ratio thermometers measure a ratio function or 'slope' between the infrared energy detected by two sensors and are not affected by atmospheric sighting problems, ie dust, steam or particulates which reduce the amount of energy transmitted, because the slope between the sensors does not change.
Since the accuracy of a ratio thermometer is not affected by a reduction in the amount of IR energy reaching the unit, the target field-of-view of the thermometer does not have to be filled, ie the temperature of a product that is smaller than the field-of-view is measured accurately with excellent resolution.
Similarly, when measuring the temperature of products with nonlinear emissivities, the slope is not affected.
There are many two-colour Raytek units installed in South Africa, measuring difficult and demanding applications. Some of these applications are:
* Monitoring klinker temperature and refractory in cement kilns where dust is a problem.
* The nonlinear emissivity problem of monitoring the temperature of steel when poured from a furnace has been solved at two major plants. This solution has also reduced the usage of dip thermocouples.
* A ferro-silicate plant where the sighting of the product is difficult and where there are also problems of nonlinearity of emissivity.
* A ceramic insulation fibre plant where the field-of-view of a stream of 'molten ceramic' at 2000°C is only 5 mm in diameter.
The above are a few examples where ratio (two-colour) infrared thermometers have solved problems that would be impossible for standard (one-colour) thermometers.
Proven indicators monitored in three dimensions ifm - South Africa
Temperature Measurement
The VVB30x continuously detects vibrations in three measurement axes and uses them to calculate proven indicators for evaluating machine condition.
Read more...Three ways to conduct thermal inspections Comtest
Temperature Measurement
There’s no universal solution for all infrared inspections with a Fluke thermal camera, also known as a thermal imager. You need to match your method to the type of equipment you’re inspecting and the level of detail you require.
Read more...Modern N1020 temperature controller
Temperature Measurement
Temperature control is a fundamental aspect of maintaining the integrity and quality of products in industries such as food processing, pharmaceuticals and healthcare. The N1020 temperature controller, designed for precision and reliability, addresses the stringent requirements of these sectors by offering advanced features and robust functionality.
Read more...Safer, simpler temperature measurement ABB South Africa
Temperature Measurement
ABB has launched an enhanced version of its NINVA TSP341-N non-invasive temperature sensor, delivering safer and simpler temperature measurements for applications in the chemical, oil and gas industries.
Read more...Smart high-precision pyrometers
Temperature Measurement
LAND, a business of AMETEK, has expanded its range of SPOT+ smart high-precision pyrometers with the launch of the M390, M3-5 and TMT for wider temperature measurement capabilities.
Read more...Detecting lubrication issues in gearbox testing by IR monitoring
Temperature Measurement
Lubrication is crucial for every transmission gearbox. Thermal imaging cameras such as Instrotech’s PI 640i can quickly and accurately detect temperature variations to ensure that gearboxes are appropriately lubricated.
Read more...Is the HVAC market in SA missing the big picture? Iritron
Temperature Measurement
The South African HVAC market is currently grappling with a pervasive mindset that prioritises lowest cost over value for money and technical excellence. However, this approach overlooks the significant benefits that come with investing in high-quality HVAC solutions.
Read more...Temperature monitoring in dairies ifm - South Africa
Temperature Measurement
Milk is a natural product whose processing requires precise temperature settings. The Berchtesgadener Land dairy uses innovative temperature sensors from ifm in key process areas.
printer friendly version