P/N 595224-01 Rev E 7/12Page 6 of 32
THEORY OF OPERATION
Thermal imaging cameras only show temperature differences between objects and
not an optical image of the objects. Experience and training are required to correctly
interpret the thermal image.
WARNING
THIS IS NOT, NOR IS IT INTENDED TO BE, AN EXHAUSTIVE LIST OF THE
BEHAVIORS OF INFRARED ENERGY THAT DIFFER FROM VISIBLE LIGHT. USE OF
THIS THERMAL IMAGING CAMERA MUST BE PART OF A COMPLETE TRAINING
PROGRAM. INTERPRETATION OF THE THERMAL IMAGE REQUIRES TRAINING
AND EXPERIENCE. DO NOT USE THERMAL IMAGING CAMERA IF YOU HAVE NOT
BEEN THOROUGHLY TRAINED IN ITS USE AND OPERATION. USE OF THIS DEVICE
WITHOUT PROPER TRAINING AND UNDERSTANDING OF ITS OPERATION MAY
CAUSE ERRORS IN JUDGEMENT BASED ON MISINTERPRETATION OF THERMAL
IMAGING INFORMATION WHICH MAY RESULT IN SERIOUS INJURY OR DEATH.
Interpretation of the thermal image depends on a variety of issues including, but not
limited to the following:
• The thermal imaging camera cannot see through walls. A source of heat behind a
wall will not be evident if it does not heat the wall itself.
• The heat from some high temperature objects or sources of high heat may be
blocked, obscured, or made less distinct in the thermal image display by any of the
following:
– Water mist, spray, or highly saturated fog
– Some chemical substances in a concentrated cloud or vapor
– Extremely dense smoke
– Heated smoke or a layer of heated gases
These are some other circumstances which could result in misinterpretation:
• If a concrete oor and a hole in that oor have the same temperature, there will be
no apparent difference in the thermal image display to indicate the presence of the
hole.
• Visually transparent or reective materials such as glass, shiny plastic, or water
can reect infrared radiation from an actual source of high temperature. The user
must be able to distinguish and identify when the image in the display could be a
reection and not the actual source of high temperature. For example:
– When viewing a window or other shiny surface at an angle, a source of high
temperature reected in the surface will be at some angle opposite and away
from the apparent location.
– When viewing a source of high temperature through a clear window with a ther-
mal imaging camera, the camera display will only show a reection of the user
holding the camera and not the source of high temperature behind the window.
– When viewing a hole lled with water, the thermal imaging camera display will
show a reection of any heat sources above and away from the water surface.
• Molten or boiling substances will appear hot in the thermal image display, but it may
be difcult to identify their physical nature and the hazards they present based on
the thermal image alone.