When a thermographer reports temperatures obtained with an imaging radiometer, maintenance personnel will frequently attempt to cross-verify reported temperatures with a spot radiometer. In such situations, discrepancies are common as the spot sizes of imaging radiometers and spot radiometers often vary widely. In order to ensure measurement accuracy and avoid discrepancies, one should bear the following in mind:

• For accurate temperature measurement, radiometers must be operated correctly and in accordance with manufacturer’s instructions
• Radiometer accuracy can degrade over time or with physical stress
• Spot radiometers will generally have spot measurement sizes that are larger than imaging radiometers
• When spot measurement sizes vary between instruments, reliable cross-verification may not be possible

To avoid discrepancies, personnel who utilize infrared radiometers should be trained in the proper use of their test equipment along with its limitations. Personnel must also understand how the characteristics of infrared instruments affect the accuracy of observed temperatures. Lastly, cross-verification of temperatures should be avoided when radiometer capabilities differ from each other.

• Accurately document when an inspection was performed
• Easily store and uniquely reference image files
• Record the duration of a thermal event

It is always good practice to consciously check your imager’s clock each time you start your imager and make any necessary adjustments. Be certain to check the clock periodically during each inspection and whenever the imager is restarted, such as after a battery change or power interruption.

If your imager frequently displays incorrect time, it may be indicative of a defective or dead internal battery. To avoid this problem, arrange for replacement of internal clock batteries whenever you have your imager serviced or repaired.