Understanding Infrared Thermography Reading 3

■ Liquid and Compressed Gases
Some instruments in the field use liquid or compressed gases for detector
cooling. The handling of these materials can be hazardous and it is the
thermographer's responsibility to learn safe practices and to adhere to
them. In general, these procedures are included in the safety regulations
for each facility. They can also be found in the operator's manuals for
these instruments. Some instruments use liquid nitrogen LN as a detector
coolant Liquid nitrogen is not very hazardous but some safety precautions
should be observed. The following four guidelincs for using and storing
liquid nitrogen are taken from the AGEMA Model 782 Operator's
Handbook:
1. Never store the liquid in sealed containers. Liquid nitrogen and similar
cryogenic liquids are always stored in Dewar flasks or the equivalent
insulated containers, with loosely fitting covers that allow the gas to vent
without building up dangerous pressures,
2. Never come into direct contact with liquid nitrogen. Serious frost bite injury
(similar to a bum) can result if the liquid is allowed to splash in to the eyes
or onto the skin.
Charlie Chong/ Fion Zhang