Understanding the Effects of Emissivity Changes on Infrared Temperature Measurement
Emissivity changes can significantly affect the accuracy of infrared temperature measurement in industrial applications. When surface properties vary—due to oxidation, material differences, or environmental conditions—so does the emissivity, which in turn influences the sensor’s ability to provide precise readings. This article explores how emissivity changes impact non-contact temperature sensing and what engineers and technicians can do to mitigate these effects for more reliable process control.
Video Overview: Effects of Emissivity Changes on Infrared Temperature Measurement
Detailed Breakdown: What the Video Demonstrates and Why It Matters
Effect of color, shape, and chemical composition (Emissivity) changes on non-contact temperature measurement
Dependence of profile emissivity from profile shape
Aluminum Profile measurements with AE3000 / A4-IN / A5-IN pyrometer
Working distance- 1000 mm, Measurement spot diameter- 10 mm
Emissivity= 0.08-0.11
Real temperature readout thermocouple
(T measured min=360C)
Emissivity= 0.04-0.06
Readout: T-2% (T measured min=400C)
Emissivity= 0.16-0.25
Emissivity= 0.1
Emissivity= 0.1-0.14
Correct readout for each emissivity
Emissivity= 0.10-0.20
The average readout for all small profiles is in the field of pyrometer view.
Small profiles measurements with measurement spot 5mm diameter
T measured min=400C – for a)
T measured min=450C – for b)
“Out of range” state – for c)
- Brightness Temperature (TB)
- 1st wavelength Brightness Temperature (TB1).
- 2nd wavelength Brightness Temperature (TB2)
- When measuring with two wavelengths, we will get two different signals.
- Using the two measured signals and the AST’s calculation algorithm
- The pyrometer will calculate the real temperature for each emissivity.
This algorithm allows accurate measurement for each type of target: flat, cylinder smooth, or bright surfaces, and for different shapes of aluminum profiles.
AST developed special pairs of analytical coefficients, allowing accurate measurements.
Different coefficients have been developed for each of the below applications:
- Profile measurement
- Hot forging
- Billets measurements
- Continuous strip and bar casting
- Hot rolling
- Molten Aluminum
Accuracy of aluminum profile temperature measurements– Most measurements are within a 1% error
Practical statistics of profiles measurements accuracy- difference between pyrometer to reference thermocouple readout in % aluminum profiles measurements
Accuracy of aluminum billets temperature measurements– Most measurements are within a 1% error
Practical statistics of AL billets measurements accuracy The difference in % between pyrometer to reference thermocouple readout aluminum billets measurements.
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