6
perform detection at night, the cameras with night vision should be chosen.
（
IR illuminator or
halogen lamp is required for night vision. IR emission distance should be suitable for the
environment.
）
Different environments will affect night vision, such as cement wall, cement
ground, green plant which could absorb IR light source. The IR range chosen should be
longer than the real hazard Detection distance. For example, for 15 meter IR range needed in
setting environment, 30meter IR range camera should be chosen, in case environment absorb
light or light spread.
）
Field background color
VFDS™ system bases on the image processing to detect fire and smoke. When the
background color is similar color to the possible flame or smoke hazard, it may effect
VFDS™ detection. For example: in figure 2.2 below, the color of the surrounding detection
environment is black and gray, in a hazard that produces black smoke, the smoke detection
will be effected. Normally, white smoke is much easy to be detected than black smoke, so
please be mindful when designing and recommending VFDS™ systems and where possible
ensure a contrast between the surroundings and the possible fire properties of the specific
flammable product.
(a) Color background (Suggest) (b) Black & gray background (Not suggest)
Picture 2.2-1Suggest for space color
