It is common knowledge that smoke detectors are critical tools in saving lives and property. They provide early warning that enables occupants to quickly evacuate a facility. With the advent of video image detection (VID), there are now ways to detect smoke and flame at the early stages of fire development. Today, video image smoke detection (VISD) and video image flame detection (VIFD) are most commonly used in critical infrastructure and unique applications. These include power generation, manufacturing, warehouse and distribution, transport, aircraft hangars, tunnels and prestige buildings — to protect people, property and production operations. VISD and VIFD are also useful where the aesthetics of a space does not warrant standard spot type detection. It’s important facilities know how VID works and what the key advantages are for video fire detection.
How Do Video Images of Smoke and Flame Detection Work?
Today’s video image detection systems rely on the resolution and accuracy of standard network security cameras (CCTV). Either a central analyzing computer or stand-alone video smoke detection camera with internal processing and relays can be installed. Images are passed through carefully developed software algorithms that use different techniques to continuously analyze the video images in real time to locate the fire incident within the field of view. In case of an event, an alarm output is sent to the fire alarm system control panel. Depending on field of view, obstructions, movement of smoke, reflections of flames, the VID may not show where a fire originates. However, both types of systems can provide control room operators with 24/7 situational awareness. Control room operators can monitor the video images in real time and assess the severity of the fire as the situation develops.
Advantages of Video Image Fire Detection
In certain applications VID technology can provide rapid detection compared to spot smoke detectors. VID detectors can detect a fire within a broad field of view of the camera, which can include very large floor areas and vertical heights. This is an advantage as typical spot type detectors are installed to protect the area directly below the device (typically 900 square feet for smoke detectors and 400-2,500 square feet for heat detectors). Also, performance of spot type detectors degrades as ceiling heights increase. Unlike many other fire detection technologies, video analytics do not need to make physical contact with smoke and can immediately ‘see’ the danger in the field of view.
In large facilities with tall ceiling heights, designers find it impractical to use conventional smoke detection devices due to maintenance and testing challenges as well as performance and smoke movement concerns in these unique spaces. Video detection systems can show higher sensitivity in detecting a growing fire faster than conventional detection — ultimately limiting the impact of serious fire incidents and minimizing the potential for high damage costs.
For aesthetically sensitive buildings such as historic structures or ornate buildings like churches or courthouses, VID provides a unique solution to provide a concealed fire detection system. A VID system can take the place of multiple spot type detectors and provide fire detection without detracting from the fire protection design intent.
How Does Video Image Detection Fit into Fire Codes?
The National Fire Alarm and Signaling Code, NFPA 72, recognizes the use of flame and smoke VID systems. The installation of these systems requires a performance-based design. Due to the variability of VID system capabilities and the differences in alarm algorithm technologies, NFPA 72 requires that the systems be inspected, tested and maintained in accordance with the manufacturer's published instructions. Numerous reliability challenges can arise due to changing ambient lighting, airflow, facility use and exposure to unexpected stimuli. VID should be very closely monitored to ensure proper operation in each unique operating environment. It is important to consult with experts who can help ensure that the technology you invest in today does not in any way compromise existing fire and life safety regulations.
Looking Ahead
While fire protection designers have used VID systems in critical infrastructure, there continues to be new applications for these systems including nuclear research facilities and automotive plants. As machine learning algorithms for smoke are being explored and new fire characteristics are being investigated, these systems are helping to make smoke and flame detection more reliable and efficient.