Measurement Preparations

The emissivity of an object depends on the material and the structure of its surface. This specifies how much infrared thermal radiation the object emits compared with an ideal radiant warmer (black body, emissivity ε = 1) and accordingly has a value between 0 and 1.

To determine the surface temperature, the tool performs a contactless measurement of the natural infrared thermal radiation emitted by the object at which the tool is aimed. To ensure correct measurement, the emissivity setting on the measuring tool must be checked before every measurement and adapted to the measuring object if necessary.

The preset emissivities in the measuring tool are reference values.

You can select one of the preset emissivities or enter an exact numerical value. Set the required emissivity via the <Measurement> → <Emissivity> menu see Main Menu.

  • Temperature measurements will only be correct if the emissivity setting and the emissivity of the object match.

The lower the emissivity, the greater the effect of the reflected temperature on the measuring result. Always adjust the reflected temperature when changing the emissivity. Set the reflected temperature via the <Measurement> → <Reflected temp.> menu see Main Menu.

Temperature differences allegedly shown by the measuring tool may be caused by different temperatures and/or different emissivity levels. If the emissivity levels are very different, the depicted temperature differences may differ considerably from the actual temperature differences.

If there are multiple objects made of different materials or that have different structures in the measuring range, the displayed temperature values are only accurate for the objects that match the emissivity setting. For all other objects (with different emissivity levels), the displayed colour differences can be used as an indication of temperature relationships.

Highly reflective or shiny surfaces (e.g. shiny tiles or polished metals) may significantly distort or impair the results shown. If necessary, mask the measuring surface with a dark, matt adhesive tape that conducts heat well. Allow the tape to briefly reach the correct temperature on the surface.

Make sure that a favourable measuring angle is used on reflective surfaces in order to ensure that the thermal radiation reflected by other objects does not distort the result. For example, the reflection of your own emitted body heat may interfere with the measurement when measuring head-on from a perpendicular position. On a level surface, the outline and temperature of your body could therefore be displayed (reflected value), and these values do not correspond to the actual temperature of the measured surface (emitted value or real value of the surface).

Measuring through transparent materials (e.g. glass or transparent plastics) is fundamentally not possible.

Consequently, the more suitable and stable the measuring conditions are, the more accurate and reliable the measurement readings are. Not only do significant fluctuations in the temperature of the environmental conditions have an impact, the accuracy can also be impaired by significant fluctuations in the temperatures of the object being measured.

Infrared temperature measurement is impaired by smoke, steam/high humidity or dusty air.

Information for achieving improved measurement accuracy:

  • Move as close as possible to the object to be measured to minimise interfering factors between you and the surface to be measured.
  • Ventilate indoor areas prior to measurement, especially when the air is contaminated or extremely steamy. Once ventilated, allow the room to reacclimatise a while until it returns to the usual temperature.

A scale (g) is shown on the right-hand side of the display. The values at the top and bottom end are oriented to the maximum (f) and minimum (h) temperature recorded in the thermal image. For the scale, 99.8 % of the total pixels are evaluated. Colours are assigned to temperature values with a uniform distribution in the image (linearly).

Different shades can therefore be used to assign temperatures within these two limit values. For example, a temperature that is exactly between the maximum and minimum value is assigned to the centre colour range of the scale.

To determine the temperature of a specific area, move the measuring tool so that the crosshairs with temperature display (k) are aimed at the required point or area. In the automatic setting, the colour spectrum of the scale is always distributed linearly (= uniformly) across the entire measuring range between the maximum and minimum temperatures.

The measuring tool displays all measured temperatures in the measuring range in relation to one another. If heat is displayed as blue in the colour palette in an area, for example in a colour representation, this means that the blue areas are among the colder measured values in the current measuring range. However, these areas may still be in a temperature range which could cause injuries in certain circumstances. You should therefore always note the temperatures displayed on the scale or at the crosshairs themselves.