Video fire detection for warehouses
Though warehouse fires usually result in few casualties or fatalities, such blazes have severe repercussions for business owners and their employees. All too often the outcome is not only total loss of content, but a total loss of building also, especially in the case of unmanned facilities. Without early fire detection technology the immensity of warehouse fire loads often results in firefighters arriving on the scene too late - the fire has already become too hazardous and too large to risk entry. Video based fire detection technologies enable faster and more accurate detection, helping firefighters limit the level of damage.
Most warehouses are characterized by high ceilings and very large areas - with huge volumes of air. It is this air volume, which presents a major challenge for traditional fire detection technologies. Usually, such technologies have been developed to discover the presence of smoke, heat or flames. In warehouse environments, heat detection by means of sprinklers is a commonly used technology, but even fully compliant sprinkler systems may not be able to extinguish the fire they detect. Using sprinklers also bears the potential of the water doing more harm than the fire itself in that they are designed to save the building, not the contents.
Smoke detection is considered to be a reliable option for early fire detection. Smoke is usually produced way before any flames become visible. However, traditional point smoke detectors need the smoke to migrate to their location, which is a challenge in large warehouses. Mounted at ceiling level, the detectors are usually far away from the source of the smoke. Moreover, given the large volumes of warehouses, the smoke is heavily diluted. A starting fire may therefore not produce enough smoke to be detected or may not have enough buoyancy to drive the smoke upwards to the ceiling where the detectors are located.
Video based technology does not have this problem. In order to provide timely detection, such technology does not need the smoke to migrate to the sensor. Video based smoke detection is basically a set of algorithms in an intelligent camera. These algorithms process the camera image to determine whether smoke is present, and can detect a fire as soon as the smoke enters the camera’s field of view. Such cameras can cover larger areas and volumes than point, beam or aspiration detectors, making them a much more affordable solution for warehouse environments. Further, in such environments video is much faster than conventional smoke detection. It can detect a starting fire within 10 to 30 seconds, while other technologies require minutes due to the slow smoke migration. When it comes to fire, these valuable minutes can mean the difference between a nuisance and a disaster.
Detect smoke and flames
Video can also do more than just smoke detection. If you use one set of algorithms to identify smoke, another set can be used to deal with the flames. Flame characteristics of different fires are well understood, and thus flame detection through intelligent algorithms is just as reliable as smoke detection. Using video to detect flames adds additional value by way of full video visualization of the scene. The operator can therefore precisely determine the location of the seat of the fire as well as of contents, potentially saving valuable time for firefighting. The video image can also be used to verify alarms in the first place, avoiding the cost of false alarms.
However, video-based fire detection (VFD) is by itself highly immune to such false alarms. Intelligent algorithms within the camera allow for very precise differentiation between a real fire and other values such as movement, reflections or changing lighting conditions. In internal tests, Bosch Security Systems has therefore achieved highest detection reliability in all test fires (TF1 through TF8) as specified in EN54.
Video-based fire detection systems scale well from a single camera to a whole networked system of distributed cameras with a central console and management system. They can transmit alarms via Ethernet to the monitoring center or even a mobile device, but can just as easily relay it to an existing fire alarm panel. Cameras cover broad areas, need little maintenance and do not even require individual power supplies. With Power over Ethernet (PoE), power and video signals use the same cable, even allowing the camera to benefit from uninterruptable power supplies (UPS) in the Ethernet switches. Video-based solutions therefore come with low cost of ownership.
Video combines safety and security
While video-based fire detection can be more reliable and more affordable than other technologies in most warehouse scenarios, it offers an additional benefit that no other option can. It enables the possibility to combine safety and security.
Having installed a video-based fire detection system, the operator of a warehouse can use the very same cameras for video surveillance. There are lots of reasons to monitor a warehouse, theft being the most obvious one. But just as intelligent algorithms can identify smoke or flames, others can detect unusual movements as well as blocked aisles or emergency exits, thus increasing safety and operational efficiency. Finally, many fires in warehouses are actually induced by intentional arson, and here video surveillance can be a very efficient means of prevention.
In the United States, the National Fire Incident Reporting System (NFIRS) and the National Fire Protection Association (NFPA) have published surveys indicating that arson accounts for 13% of all warehouse fires (second only to electrical problems with 14%). And being designed for destruction, arson causes much more damage than incidental fires. Representing 13% of the fires, arson resulted in 21% of the damage done. In the UK, the Fire Protection Association (FPA) have also published data indicating that arson was responsible for 46% of all large fires in warehouses in the late 90s. Video surveillance, combined with video-based fire detection can therefore not only offer fast and reliable detection of warehouse fires, but potentially also prevent many of them from happening or help with root cause analysis.
Two approaches to VFD
There are two different approaches to video-based fire detection. VFD can complement existing technologies such as sprinklers or smoke detectors, greatly increasing the speed and accuracy of fire detection. Warehouses aside, there are many other scenarios where solutions exist, but are unsatisfactory. These include environments with high rooms, dusty and humid areas or very large open spaces. On the other hand, VFD can be a solution for applications where no other solution exists. Think of saw mills with their extreme fire load - according to the NFIRS and NFPA sawdust is also the most common material to ignite in warehouses. Hangars, or large monitoring areas such as generator halls in power plants are other common examples.
Preconditions for VFD
Although video-based fire detection offers many benefits including additional safety, it must be noted that it so far cannot replace EN54 installations. This is an Active Work Item in ISO, however, and so certification can be expected in the not so distant future. FM3232 and UL286B are available as it stands today. However, VFD is one of the best available options where no EN54 compliant solution is in place. In some situations VFD can also improve the chances of obtaining insurance coverage for properties that were previously uninsurable. In other scenarios it provides an excellent complement to existing fire alarm systems, increasing the safety level and integrating video surveillance.
Another challenging condition for video fire detection is of course light. Flames and/or smoke must be visible to make it possible for the video camera to actually detect a fire. Bosch currently offers VFD on its IP camera starlight 8000. The company’s starlight series is specifically built for extreme low light conditions, which will, once integrated, offer video-based fire detection in very unfavorable lighting conditions.
