Understanding Infrared Thermography Reading 3

Moisture in Airframes
The detection of moisture in airframe sections can be accomplished
thermographically because of the endothermic process that takes place when
there is moisture ingress in an airbomc structure and this water freezes.
When thermal images are taken immediately after the aircraft lands. the skin
above the sections where moisture has entered show up as cool spots on the
thermogram, as seen in Figure 5.2. (does the heat capacitance qualified as
endothermic process?)
In chemical processes, an example of an exothermic reaction is the
installation of foam-in-place polyurethane insulation. As the liquid chemicals
are released into the cavity, they solidify into a foam and release heat. This
heat is conducted into the walls of the cavity wherever the foam is produced.
As a result. the cavity walls are uniformly heated by a successful blow. A
thermographic investigation can evaluate the effectiveness of this process by
mapping the uniformity of the temperature distribution on the outside walls
cool spots would indicate sections where the foam had not migrated.
Charlie Chong/ Fion Zhang