the discussion turns to temperature sensing, thermocouples get most
of the attention. For determining surface temperature, however, especially
when the surface may be moving, rotating, or inaccessible, no high-tech
instrumentation outperforms phase change indicators.
to electrical or electronic instrumentation include vulnerability to
external factors such as static electricity, ionized air, humidity ,
and being dropped. Electronic devices also require trained operators
with technical understanding and skill. Remote-reading infrared sensors
present fewer problems but still need skilled operators.
indicators, in contrast, take advantage of precise melting points of
different materials and are easy to use. Tempil's phase-change temperature
indicators are made of materials with melting points calibrated to a
guaranteed accuracy of 1%. There are more than a hundred temperatures
between 100 and 2500F (38 to 1,371C) available to be chosen. The indicators
do not read out an exact temperature. But by melting they let users
know exactly when a preset minimum or maximum has been reached.
react within milliseconds, unlike thermocouple or probes that must reach
equilibrium with the surface and have to compensate for heat conducted
away from the region being tested. Phase-change materials, on the other
hand, are in intimate contact with the surface being measured, and only
need someone who can see that a dry chalk mark has melted or a label
include no set-up, calibration or recalibration periods. They are also
relatively immune to abuse, unlikely targets for pilferage.