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.

Press up or down on the multi-function button (12) to call up the set emissivity in the emissivity indicator (c) (together with the reflected temperature indicator (e)). Both values also appear for a few seconds on the display after switching on the measuring tool and after exiting the main menu.

You can change the emissivity via the main menu  see Main Menu at any time. You can select one of the preset emissivity levels or enter an exact numerical value.

The preset emissivities in the measuring tool are reference values.

Note: If there are several objects with a different emissivity being measured within the measured area identified by the laser, the temperature measurement can be distorted.

The lower the emissivity of the object to measured and the more thermal radiation the object to be measured reflects, the greater the effect of the reflected temperature on the measuring result. For this reason, set the correct reflected temperature particularly at low emissivity, as otherwise the measuring result may be significantly distorted.

In some situations (especially in indoor areas), the reflected temperature corresponds to the ambient temperature. However, the reflected temperature may also be significantly affected by objects with greatly deviating temperatures: For outdoor measurements, the sky may be reflected in the object to be measured, for example, when the sky is clear at a temperature as low as −40 °C.

Press up or down on the multi-function button (12) to call up the set reflected temperature in the reflected temperature indicator (e) (together with the emissivity indicator (c)). Both values also appear for a few seconds on the display after switching on the measuring tool and after exiting the main menu.

You can change the reflected temperature via the main menu  see Main Menu at any time.

The laser points generated by the measuring tool border the exterior circular measured area. The measured value (n) shows the average surface temperature within this area.

Increasing the distance between the measuring tool and the object  see Technical Data you are measuring will increase the distance between the laser points and consequently the size of the area measured.

Highly reflective or shiny surfaces (e.g. shiny tiles or polished metals) may significantly distort or impair the results shown due to their often very low emissivities.
In this case, completely mask the measuring surface with a dark, matt adhesive tape that conducts heat well. When masking, bear in mind that the measuring surface increases with increasing measuring distance.
Allow the tape to briefly reach the correct temperature on the surface. Set the typically higher emissivity of the adhesive tape on the measuring tool.

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 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:

• Select the measuring surface so that the interfering factors are minimised. Bear in mind that the measuring surface increases with increasing measuring distance.
• 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.