Addressing Superior Fire Detection
Saving Money by Monitoring Smoke Sensor Sensitivity
Analog addressable systems also can save time and expense by conducting routine sensitivity tests. According to Sections 10.4.3.2.1 and 10.4.3.2.2, NFPA 72, National Fire Alarm Code, 2002 Edition, sensitivity testing must be conducted one year after installation and every other year thereafter.
“Where the AHJ [authority having jurisdiction] requires a [smoke detector] sensitivity report, we can do a complete rundown on the sensitivity of each smoke detector that will show the range of every single device,” says Wolk.
Section 10.4.3.2.3 and its two subsections allow fire technicians to extend sensitivity testing to a five-year cycle, providing 1) the detector(s) has proven stable for the past two years, and 2) a detailed report of all events related to said detector(s) is maintained. Addressable systems equipped with network connections or printers are able to do just that.
“If the system has a printer, a detailed history of each detector can easily be maintained,” says Wolk.
Section 10.4.3.2.4, NFPA 72, 2002, allows for several kinds of sensitivity tests. In 10.4.3.2.4(3) it calls for “Listed control equipment arranged for the purpose,” and in 10.4.3.2.4(4) it calls for smoke detectors designed to send a maintenance warning to the fire alarm panel. These smoke detectors have the ability to test their own sensitivity and then adjust the alarm threshold, accordingly.
Another potential cost-savings feature in some addressable systems relates to placement of the notification appliance circuit (NAC) devices on the same SLC with the initiating devices, just as relay output modules do.
In this case, each NAC device has a built-in addressable module that connects to the SLC. This module, just as an initiating device or relay output module, must be addressed. This allows the fire alarm panel to interrogate and determine status.
When configured in this manner, an additional set of conductors must be installed to each NAC device. In many cases, despite the additional power cable, this practice saves time while providing a level of control over NAC devices that a common NAC circuit cannot provide.
Analog Addressable Panels Adjust for Environmental Conditions
Another helpful feature that analog addressable systems are known for is the adjustment of smoke detectors found outside their rated sensitivity range.
During routine sensitivity testing by the main fire alarm panel, if a smoke detector’s sensitivity to smoke has changed, the panel can adjust the detection threshold for that detector.
“One of the key features of an analog addressable system is to monitor the health of each sensor. As a sensor gets contaminated, over time the panel can adjust the sensitivity of the device so it’s still providing the same level of protection as when it was first installed,” says Notifier’s Ebersold.
This is a powerful feature because it prevents what would normally have been a false alarm. Upon such an adjustment in sensitivity, today’s analog addressable systems will then issue a warning, both locally at the annunciator(s) and remotely at the supervising station.
“If you service them correctly and efficiently, false alarms should never be a problem. But if you do nothing to fix the problem, the system will eventually go into alarm,” says Wolk.
Addressable to Become de Facto Standard in Fire Detection
Because of the power inherent within addressable technology, and because the price tag is dropping, many experts believe addressable systems are poised to become the predominant alarm technology in the fire detection market.
“I do believe that addressable will become the status quo as we’re selling our smallest 50-point addressable in the six- to 10-zone conventional area,” says Jeff Hendrickson, director of marketing for Silent Knight of Maplegrove, Minn. He says the only thing conventional panels are still holding onto is the small two- to four-zone applications.
“I think that, over time, the price point will take over. There may always be conventional panels out there, but they will be the minority. It’s only a matter of time until the price point is such that it puts conventional panels out of business,” Hendrickson adds.
“We’re seeing a decline in conventional panel sales because people recognize the advantages of analog addressable, as cost is not that much of a factor anymore,” agrees Ebersold. “In fact, the cost of an addressable system is not that much more than a conventional system.”
Another issue is scalability where conventional panels have a limit as to how large the system can be built. According to Ebersold, the Notifier line of addressable systems goes as low as 50 points and as large as 3,180. But, “our larger addressable panels can be networked together, so you can do systems that consist of thousands of points of protection.”
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