How the infrared thermometer determines slope and emissivity
How to Determine Slope
Effective methods for determining slope include measuring the temperature of an object using a probe (such as an RTD), thermocouple, or other suitable method. Once the actual temperature is obtained, the emissivity setting is adjusted until the temperature reading from the sensing head equals the actual measured temperature, i.e. the correct slope value is obtained.
How to determine the emissivity
1. Determine the actual temperature of the object using a probe (e.g. RTD), thermocouple, or other suitable method. Adjust the value of emissivity until the temperature reading of the sensing head is the same as the actual temperature, then the correct emissivity is obtained.
If a portion of the surface of the object can be coated, the surface of the object can be blackened with a non-glossy carbon black, at which point the emissivity is approximately 0.98. Set the emissivity to 0.98 and measure the temperature of the blackened portion. *Afterwards, measure the area adjacent to the blackened portion of the object and adjust the emissivity until the temperature reading is equal to the actual temperature. The correct emissivity is then obtained.
Optimise the measurement of surface temperature according to the following guidelines:
1. Use a measuring instrument to determine the emissivity of the object.
2. Avoid reflections as much as possible; shield the object from high temperature heat sources in the surrounding environment.
3, When the object is hot, if several partially overlapping wavelengths are available, select the shorter wavelength.
4, for translucent materials, such as glass; temperature measurement should ensure that the background temperature is uniform and lower than the object temperature.
5, when the emissivity is less than 0.9, the sensing head and the surface of the target object should be kept as perpendicular as possible. Don't let the angle between the axis of the sensing head and the normal of the object surface is greater than 45 °!
