Fluke TiR1 FE Ti10-25-Tir-1 Users Manual - Page 19

Thermal Imagers Setting Emissivity (Ti25 and TiR1 only) the object's surface. The Imager detects the infrared energy from an object and uses this information to estimate the temperature of the object. Most of the objects measured such as painted metal, wood, water, skin, and cloth are very efficient at radiating energy and it is easy to get very accurate measurements. For surfaces that are efficient at radiating energy (high emissivity), the emissivity factor is estimated to be 95% (or 0.95). This estimate works for most purposes. This simplification does not work however, on shiny surfaces or unpainted metals. These materials are not efficient at radiating energy and are classified as having low emissivity. To accurately measure materials with a low emissivity, an emissivity correction is necessary. The easiest correction method is to set the Imager to the proper emissivity value so the Imager automatically calculates the correct surface temperature. If the Imager uses a fixed emissivity value (meaning that it is set to one value and the user cannot adjust it), then the Imager's measurement must be multiplied by a value found in a look up table to get a more accurate estimate of the actual temperature. The TiR1 and Ti25 have the ability to set emissivity by directly entering a value or using a table of built-in values. The TiR and Ti10 have emissivity that is permanently fixed at 0.95, which works well for most surfaces but can provide very inaccurate reading if used directly on a shiny metal surface. A significant amount of information is available on emissivity. Further study of this topic is recommended to get the most accurate temperature measurements using the Imager. Setting Emissivity (Ti25 and TiR1 only) Setting your Imager with correct emissivity values is critical to making accurate temperature measurements. To set the emissivity value: 1. Press a until Emissivity appears over c. 2. Press the softkey labeled Emissivity. At this point, emissivity can be set directly as a value or selected from a list of emissivity values for some common materials. To select from a list of common materials: 1. Press the softkey labeled Table. 2. Press the softkey labeled Up or Down to move between the materials in the list. The emissivity value for each material is shown on the screen as the selection moves between the different materials 3. Press the softkey labeled Done to select the highlighted material. 13