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image also shrinks; this may lengthen the flame detection time, or even fail to detect the
flame.
Please refer to appendix I to find the example of the whole design flow.
The required protection region in picture 2.7-4 can either be the whole region, or only the
region with combustible (smaller region). However, the flame source may not be at the
region with combustible, hence the whole region to be set as the required protection region is
highly recommended.
Pic. 2.7-4 Camera focal length and viewable angel relation
(a) Wide viewable angle
but short detection
distance –
inadequate
protection area.
(b) Fix viewable angle but
change camera’s position -
inadequate
protection area.
(c) Decrease viewable
angle and increase focal
lenth -
inadequate
protection
area.
(d) Add cameras and adjust
cameras positions -
Adequate
protection area.
Enabled detection area
required protection region
required protection region
required protection region
required protection region