How to Determine Slope and Emissivity for Infrared Thermometers
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 is equal to 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, i.e. the correct emissivity is obtained.
2. If a part of the surface of the object can be coated, the surface of the object can be blackened with non-glossy carbon black, at which time the emissivity is about 0.98. Set the emissivity to 0.98 and measure the temperature of the blackened part. *Set the emissivity to 0.98 and measure the temperature of the blackened portion. Then 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.
3Optimize the surface temperature measurement 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 has a high temperature, 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. Do not let the angle between the axis of the sensing head and the object surface normal is greater than 45 °!
