If you get one with adjustable emissivity (like the ThermoWorks one in the previous link) you can correct for different surfaces. The emissivity is a number from 0 to 1 that says how efficient the surface is at radiating heat (in this case in the infrared, where these devices make their measurements). The default setting of that one is 0.95, essentially saying that the surface is assumed to be very black, and thus a very good absorber/emitter. (Both go together.) If the surface is shiny, it doesn’t radiate as effectively at a given temperature. So the IR gun measures less emission from that surface, and interprets it as a lower temperature, rather than as a different surface at the correct temperature.I've used a few at work, and see no difference in them. They all work. But I believe there are some problems with reflective surface.
^^That. Otherwise you are reading numbers, but they don't mean anything. Temps read out can vary a LOT if emissivities are wrong for the material (and surface) used. There are many tables online with emissivities for different materials and finishes.If you get one with adjustable emissivity (like the ThermoWorks one in the previous link) you can correct for different surfaces. The emissivity is a number from 0 to 1 that says how efficient the surface is at radiating heat (in this case in the infrared, where these devices make their measurements). The default setting of that one is 0.95, essentially saying that the surface is assumed to be very black, and thus a very good absorber/emitter. (Both go together.) If the surface is shiny, it doesn’t radiate as effectively at a given temperature. So the IR gun measures less emission from that surface, and interprets it as a lower temperature, rather than as a different surface at the correct temperature.
Figuring out what emissivity to use to measure a shinier surface is a little tricky, but in principle you could do something like this:
- Put some black tape on your shiny surface (when it’s not too hot!).
- Measure the temp of that tape.
- Measure the temp of a non-taped part of the shiny surface; it should read too low.
- Adjust emissivity setting in the thermometer until it reads correctly on the shiny surface.
- Make a note of that setting for future use on that particular surface (but be sure to change it back for use on other, darker surfaces).
Alternatively, if you know the surface is at room temperature, you could do the above adjustment without having to put tape on it - just compare to a darker room-temperature surface.
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