Motion Detection Technology Searches For Earliest Indication Of Emergencies
Vol 20 No 4
Smoke is often the earliest indication of what might become a major industrial emergency. Utilizing sophisticated software joined with closed circuit television surveillance, Fire Sentry's Visual Smoke Detection (VSD) system can deliver an early warning of fire at the incipient stage, long before the actual flames are visible.
VSD employs technology originally developed for video motion detection systems, Simek said. "Smoke makes a unique pattern when its aspirated and we're able to detect that pattern. The system samples several video frames per second and then compares each frame with the next, pixel by pixel."
The system can distinguish smoke from steam, fog, airborne dust and other debris that might be suspended in the atmosphere, Simek said. Speed of response varies based on the type of smoke, weather conditions, and how sensitive the system is set-up. "I've witnessed our smoke detection system respond before I could see the smoke," Simek said.
Distance is a major advantage that visual systems that detect smoke have over conventional sensors.
"Say that you are using a camera and a point device to monitor the same room," Simek said. "The smoke has to migrate to that point device for it to be sensed. With a video camera, all the smoke has to do is appear within the field of view of the camera. Our system detects the smoke much closer to the source than conventional sensors."
Unlike with conventional sensors, the camera does not have to be placed in a hazardous area to detect hazardous conditions, Simek said.
"The National Electric Code has a criteria for specifying hazardous locations depending on the severity of the hazard," he said. "Class 1, division 1 is the least safe of all the areas they specify. Generally, to be able to put any electrical equipment into a classified area you need to have it tested and certified by an authoritative body. Cameras that are placed outside of the hazardous area don't require the same type of certification."
Using a dedicated computer and equipment including proprietary hardware and software, the VSD systems can "piggyback" on existing security surveillance systems already in place, Simek said. Fire Sentry does have Factory Mutual approval on its VSD control systems.
"We do have some minimum requirements for the camera but any new CCTVs manufactured today exceed those requirements," Simek said.
Currently, a single Fire Sentry VSD system can accept up to eight video feeds simultaneously. However, the signals must be fed through the VSD system before it is multiplexed.
Also, the system can be optimized to allow for the variations in lighting throughout the year and even in a single day. "Optimization is something that happens over a period of time," Simek said. "Each location is different. If you have someone on your staff who is fairly knowledgeable about cameras it doesn't take much to bring them up to speed about optimizing a camera."
Although the system does work under low-light conditions, some areas may require additional illumination for the best results. The use of infrared cameras and lighting may be an option, he said.
Rather than installing the VSD system and then testing, Fire Sentry can take the preliminary step of analyzing the video feed from the existing surveillance system. "Just tape 10 to 15 minutes of video feed from the particular location and send it to us," Simek said. "We plug it into our VSD system just like it was a live camera. That way we may be able to tell the customer whether the system is suitable or not and give the reasons why."
VSD does have its limiting factors. The camera in use must be fixed on one location. No automatic panning, zooming or tilting is allowed. "We're trying to detect a moving object or a pattern of smoke so the camera has to be looking at a fixed position," Simek said.
No detection system is perfect, Simek said. However, VSD technology offers a very high degree of accuracy.
Smoke will never be a welcomed sight at plants and refineries. However, video smoke detection systems represent a powerful new tool in the fight against the type of property loss and injury that usually follows its arrival.o
To contact Fire Sentry, call (714)671-1100 or e-mail them at firstname.lastname@example.org.