A UV detector
can detect almost every fire,
Hydrocarbon as well as non-Hydrocarbon. An IR
detector based on 4,4µ radiation (CO2
emission of a fire)
can only detect Hydrocarbonfires like burning Wood,
Paper, Petrol or Natural Gas. Non-Hydrocarbons
like Hydrogen, Magnesium or Sulfer burn without CO2
emissions and cannot be detected with a traditional IR
or UV/IR (AND) detector.
Spark detectors are able
to detect sparks or embers
within a few milliseconds. The SenseTronic spark
detection systems are ATEX
approved for use in Hazardous areas.
It means that when the distance from the detector
to the fire is doubled
the fires needs to be four times larger. E.g. a detector detects a
0,09 m2 (1 sqft) petrol fire
at 15 meters (45 ft). In order to see the fire at 30 meters (90 ft) the size
of the fire needs to be at least 0,36 m2 (4 sqft).
An inhibitor is a substance or vapour that
blinds the flame sensor.
E.g., a UV detector will
be blinded by oil or grease on the lens, Hydrocarbon vapours
like Xylene and Toluene, Chloride based vapours etc.
An IR detector will be
blinded by fog, water and ice or a salt layer on the lens (salt takes up water).
A multi IR detector can
be blinded or masked by black-body radiation from hot machinery or
direct sunlight.
The user looses faith and maybe a real fire
alarm is discarded out of disbelieve. A UV
detectorfalse alarms to the radiation of Arc Welding,
Halogen lamps or high pressure mercury lamps (without the protective
glass), corona en static arcs. An IR
detector may false alarm to chopped black body radiation and
in some cases direct chopped sunlight. Multi
IR sensors are less susceptible to black body radiation or
chopped sunlight but may get insensitive.