The detection of smoke, radiation, and chemicals is of great importance in industrial
processing not only as it relates to the safety of humans and the control of
environment pollution both atmospheric and ground, but is also used in process
control applications to detect the presence, absence, or levels of impurities in
processing chemicals.
Smoke detectors and heat sensors (automatic sprinklers) are now commonplace
in industry for the protection of people, equipment, and monitoring and
control of chemical reactions. Low-cost smoke detectors using infrared sensing
or ionization chambers are commercially available. Many industrial processes
use a variety of gases in processing–such as inert gases (nitrogen)—to prevent
contamination from oxygen in the air, or conversely, gases or chemicals can be
introduced to give a desired reaction. It is therefore necessary to be able to