Addressable Systems Help Save Lives, Time
The fire detection industry has made some spectacular advances in the way fire alarm control panels (FACP) operate. For example, through the miracle of addressable and analog-addressable technology, the FACP is now able to quickly identity the exact source of alarm, trouble and supervisory conditions.
The difference between addressable and analog-addressable systems is rather simple, but the technology itself is anything but. A strict addressable system acts to provide the exact location of a device that has gone into alarm, supervisory, or trouble. Analog-addressable systems, by contrast, will provide the FACP with raw environmental data that relates to a sensor’s immediate surroundings.
“Addressable panels give the client a wealth of information to base decisions and courses of action on at a price much lower that a custom-built system,” says Tom Glendinning, president of Savannah, Ga.-based Global Security Industries. “It can indicate the type of alarm and exact location, and it can open doors that need to open and close those that need to close. It can turn off fans that blow and turn on fans that vent. It can provide notification devices in just the affected area of large systems.”
Fire alarm equipment manufacturers have included a baker’s list of helpful features within today’s addressable and analog-addressable fire alarm systems that are appreciated by fire technicians and firefighters alike.
In addition to being able to pinpoint trouble spots, addressable systems can also provide more specific information about the nature of the fire as well as the detection equipment itself, in terms of performance and maintenance. All of these capabilities also make these systems better equipped to avert false alarms.
Addressable vs. Conventional – The Former Has Many Advantages
Early conventional FACPs consisted of one or two indicating device circuits (IDCs) and a notification appliance circuit (NAC). These systems were effective in warning occupants in a small structure of a fire.
Larger panels with multiple IDCs and NACs eventually took their place, allowing fire technicians to better pinpoint alarms and problem situations, as well as target specific areas or floors of large facilities when evacuation became necessary. The use of multiple NACs also allowed for specific voice and tonal messages that require occupants to move to specific safe locations within a burning building.
Multiple IDC and NACs alone, however, have not solved the industry’s incessant need for detail. Knowing which end of a building the fire is in, or which floor, is not always enough. Firefighters and fire technicians often need to know the exact location of a sensor in trouble or one that has errantly gone into alarm.
Addressable and analog-addressable technology provides a solution for such needs. In the case of a hood fire in a kitchen on the 17th floor of a 50-floor high-rise office complex, an addressable system can tell management and firefighters the exact location of the fire. The same situation using a conventional system would require a physical search of the floor in question until the fire was found.
The addressable connection is made with a special hazards system using an addressable dry contact input module. The fire technician connects the module’s input terminals to the suppression system output relay. The module’s output is then connected to one of the signaling line circuits (SLCs) that comes from the addressable FACP.
At least one SLC will be found to travel throughout the building, but there may be more, depending on the size of the installation. The addressable dry contact module is used to transmit a unique identifier to the FACP panel, along with a variety of other data. Addressable systems can also save fire technicians an inordinate amount of time and effort when it comes to servicing fire alarm problems.
“Our tech went to a jail where five smoke heads were indicating supervisory,” explains Glendinning. “We were able to determine the wire route and the last working sensor. When we went to the cell in question, we found that the prisoners were trying to arc the wires so they could light a cigarette, only they did not get much of an arc from 24VDC. I can tell you, analog-addressable saved us hours of wire tracing.”
Systems Go Above and Beyond Detection to Provide More Details
Some fire technicians mistakenly believe that the main function of a fire alarm system is to detect a fire in progress and notify the occupants. Although this is certainly one of the primary objectives, it is by no means the only one.
The simple fact is that firefighters need as much information on a fire’s location as possible. Once they arrive on the scene, it is also important to be able to discern the fire’s direction of travel and velocity. Having a wealth of information will help them locate and quickly extinguish the blaze. More importantly, it increases the likelihood of a successful search and rescue operation as firefighters look for trapped survivors.
The multiple-layer communication potential of the technology used in analog-addressable fire alarm systems is what makes all of this possible. No longer must the FACP rely on only one environmental characteristic when determining whether a fire is present in the building. No longer must firefighters enter an involved structure without knowing more than the general zone.
Using multiple-sensor detection devices, for example, FACPs can glean a variety of data from an analog-addressable smoke detector and process it in a variety of ways. A multiple-sensor smoke detector, for example, may contain a photoelectric smoke chamber and a thermal detector. In addition to these elements, it may contain an ionization chamber.
“Today you have sensors that look at two or three characteristics. If you put all of these into an analog sensor and you send the data back, the control panel does not look at just one, but it takes them all into consideration,” says Michael Minieri, a consultant for Los Angeles-based TRCsolutions.
Instead of preset points with a single characteristic to trigger an alarm, multiple-sensor detectors provide real-time environmental data. “When it sees a pattern with these characteristics developed, it is indicative of an actual fire,” adds Minieri.
Multiple-Layer Technology Minimizes Unwanted Alarms
Multiple-sensor detectors can also help fire technicians avoid false and unwanted fire alarms.
“No fire alarm system today is capable of actually detecting a fire. Instead, all of these systems rely on the detection of environmental data that usually accompanies an actual fire,” states Minieri. “The problem is that no one characteristic used for the detection of a fire can be reliably used to indicate the existence of a real fire.”
For this reason, fire alarm systems often go into alarm without just cause. Yet, many times these systems have truly detected something that caused them to sound the alarm, even though it was not a real fire.
For example, if the ambient temperature in the vicinity of a conventional rate-of-rise heat detector rises too quickly, a false alarm will occur because air inside the rate-of-rise portion of the sensor cannot vent fast enough to avoid closing the alarm contacts. Of course, there is no way for the sensor itself to know whether the rapid rise in temperature originated from an actual fire or some other source, such as a plumber’s torch applied to a nearby copper pipe.
Thus, an alarm goes up, the arriving assistant fire chief is unhappy and the client pays a hefty fine.
Another example of an unwanted, or mistaken alarm can be witnessed when the local cigar-a-month club meets in a rather small room. Unfortunately, the nearby smoke detector has no way of knowing that the minute particulates it has detected are that of cigar smoke -rather than a legitim
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