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1.3
OPERATING NOTES
Interpreting The Image - Relative Temperatures
.
The image displayed is simply a black and white picture of the infrared energy
entering the lens. The camera displays relative temperature differences between
individual objects and their surroundings, irrespective of overall ambient
temperature.
The camera is set up to display objects at various shades, from black for cooler
items to white for hotter bodies, i.e. in a room at 20 8C a cold drink would
appear black whilst a hot radiator would appear white. In a room at 250 8C,
however, it is possible that the same hot radiator may appear darker than, for
example, burning materials.
Identification of Fire and Hotspots
.
The camera will represent zones of very high temperature as white zones within
the picture. Very small fires or smouldering material will cause the automatic iris
to close down slightly, but the image of surrounding objects will remain clearly
visible.
Hidden Fires
.
It is possible that fires may be burning or smouldering behind doors, in ducting
or indeed in wall or floor cavities. In such circumstances, the operator should
look for areas which appear whiter when compared with the surroundings. For
example, a fire behind a door will cause the door to appear whiter against the
background. Similarly, a white area on an otherwise dark wall could indicate the
area of fire behind the masonry.
8
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