Definition
Video smoke detection is the recognition of the characteristic movement and change in air transparency within a camera view that indicate smoke. The method works at a distance and does not require smoke to reach a measurement point, which sets it apart from a point detector.
Where it beats a point detector
A point detector reacts once smoke reaches it. In a hall over ten metres high, in a space with strong draughts or in an open yard, that can take a long time or never happen at all.
A camera watches the whole area at once and reacts to smoke anywhere in it. It proves useful in high-bay warehouses, car parks and bulk material yards.
Limitations and false alarms
Detection is confused by phenomena that look like smoke: water vapour, dust during transfer, exhaust from combustion forklifts, fog at a gate on a cold morning. Each has to be accounted for while tuning the system.
The method does not replace a fire alarm installation where regulations require one. It is an early warning layer operating below the threshold of the primary system.
Frequently asked questions
Does it detect fire or only smoke?
Both, though smoke usually appears first and gives the earliest warning. Flame is recognised by its characteristic flicker and colour.
Is a thermal camera required?
Not for smoke detection. A thermal camera helps detect overheating before visible smoke appears.
Does it work outdoors?
Yes, although a stable background is harder to obtain in the open, so tuning takes longer and an observation period should be expected.