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Heat seeker: Surveillance offers viable alternatives to smoke detectors


June 26, 2019
By Colin Bodbyl


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When most people think of fire detection, they think of traditional smoke detectors that seem to false alarm every time someone burns a piece toast.

There are, however, other methods for detecting fires that many do not know of, one of which is surveillance cameras. Traditional sensors work well in home and office environments but outdoors or in large open spaces like factories or stadiums they are not a good solution. For these applications, integrators often look to specialized video surveillance cameras purpose built for fire detection.

There are several methods of detecting fires using a camera. The first is using video analytics designed to identify smoke in a scene. Smoke is typically the earliest sign of a fire as objects often smoulder and generate smoke before flames appear. For indoor applications, this technology can be very effective. Using smoke detection analytics outdoors can increase the likelihood of a miss, and in many cases, manufacturers do not recommend using smoke detection outdoors. Strong winds can quickly clear smoke from the air, making it difficult to detect. Other environmental factors, like poor lighting or fog, can further confuse the analytics.

Another analytic for detecting fires that is less prone to the effects of wind and lighting is flame detection. Similar to smoke detection, flame detection analytics are designed to identify the unique appearance of flames in a scene. Since flames generate their own light and are less affected by weather, flame analytics can be very effective. The obvious downside is that the camera needs to have a line of sight to the flame. It is also possible that by the time a flame is detectable, the fire has grown significantly from the time it first began to generate smoke.

If smoke or flame analytics will not meet the requirements of a site, thermal cameras could be a better choice. The simplest way to understand thermal cameras is as a camera that detects the temperature of objects in a scene. Since thermal cameras can measure temperatures, they can also be set to trigger an alarm when objects heat up past a certain threshold. Not all thermal cameras are capable of measuring or alarming on high temperatures, so specific models need to be selected in order to monitor for fires.

As with fire and smoke analytics, thermal cameras are not perfect. Thermal cameras also need a line of sight to the heat source in order to detect it. This can be particularly problematic in the case where an object like a house or building is on fire inside and generating smoke, but the outside of the facility has not warmed past the set threshold yet.

Combining any of the above solutions can be the best defence against fires, and many vendors do offer cameras that support combinations of the above three technologies. Whether using an individual technology above or some combination of the three, false alarms are to be expected. Not unlike the smoke detector in your home that cannot distinguish between smoke from the toaster and smoke from your furniture, fire detection cameras will also false alarm on anything that appears to be a fire. Hot machinery, exhaust smoke, and other innocuous activity can trick fire detection cameras into generating false alarms. Regardless of false alarms, however, video surveillance cameras can create an effective fire detection system, particularly in large open spaces where traditional smoke detectors simply will not work.

Colin Bodbyl is the chief technology officer of Stealth Monitoring (www.stealthmonitoring.com)