This type of equipment employs an infra-red camera and produces a thermal image (photograph) which may be either directly observed or computer analyzed for anomalies.
Thermal imaging is a very useful tool for close monitoring of hazards such as bunkers and silos; however, it is not usually practical for long distance monitoring of large areas such as aircraft hangars and power stations.
 

These are designed to detect sparks and very small visibly glowing embers. These types monitor for short IR wave lengths that are at or near the solar band and are mainly intended for installation in ducts where there is a zero level of ambient lighting.
Spark detectors are not solar blind and the IR filters (e.g. 0.4 to 1.6 microns) do not permit detection of IR emissions from relatively low temperature abnormalities such as pre-ignited PRB coal.
 

This infra-red sensor type employs IR filters that select longer wavelengths (eg >5 micron) and is truely “blind” to the visible spectrum. These detectors can register both the high energy emissions from very hot / burning objects, and those from abnormal but relatively low temperature material transiting the field of view. The Patol Series 5000 detectors are of this type and are particularly suited to the close monitoring of harards such as coal conveyors.  See links at page top and bottom for more information.

The Patol Series 7000 detectors monitor for the peak IR emissions that occur at about 4.3 micron due to the combustion of hydrocarbons. These emission spectra are not the same as for “black body” radiators as defined by Planck.
The 7000 units also monitor for emissions in the 5 to 14 micron band.
A condition where IR emissions occur at 4.3 micron but not in the broad band above 5 micron is a signature unique to a hydro-carbon flame.
The Patol 7000 detectors analyse and respond to this condition.

It is this type of detector that is best suited to monitoring of large
spaces such as aircraft hangars and power station turbine halls.
 PATOL 7000 SERIES ARE FLAME DETECTORS