False alarms and the unpredictable nature of fires are a dangerous combination. However, advances in technology have cleared the way for new products and approaches.
In recent years, designers and manufacturers of fire alarm systems have pushed beyond conventional technologies into the realm of distributed intelligence. Like most revolutionary ideas, distributed intelligence rests on a deceptively simple premise: spread the computing power of a life safety system among its devices to free the control panel from mundane processing tasks and decentralise the system's core processing functions.
In itself, distributed intelligence is nothing new. The Internet, for example, was originally conceived decades ago to provide a kind of life safety system to support military communications in the event of war. On a smaller scale, modern fire alarm systems provide the same fail-safe back-up that enables them to continue to provide basic life safety functions, even if the control panel or network node is knocked out of action.
Today's intelligent life safety devices have the capacity to do more than simply send information to the control panel. The result is something that is both subtle and complex. Intelligent systems monitor their surroundings and adjust themselves to compensate for naturally occurring environmental conditions. This means they have the ability to differentiate between smoke and something that may look like smoke.
The driving force behind this development has been the need for a design that is more reliable and less susceptible to nuisance alarms. This has been accomplished through modifications in the way information is processed, rather than the way it is gathered: although tremendous gains in detector reliability have been made over the past few years, the basic principles of detection have remained virtually unchanged. Ion, photo and heat sensors - the mainstays of any fire alarm system - still have their own specific applications for which they are best suited.
Trade-offs characterise past approaches
As fires have unpredictable natures, manufacturers have found it necessary to modify detectors to perform reasonably well under a range of conditions. For example, a photoelectric detector must also be able to respond to a smouldering fire. The result is a device that operates reasonably well, but not optimally.
The trade-off has come at a price and false alarms have become the nature of the beast. The problem is that detectors sensitive to smoke are also sensitive to dust; those sensitive to heat can also be affected by humidity.
Intelligent systems have found ways to overcome this problem. With the introduction of the analog detector a few years ago, and addressable devices before that, manufacturers were able to assign sliding alarm thresholds to devices. This made it possible for the device to monitor its own sensitivity and understand its environment.
Onboard microprocessors have also provided a way of addressing another concern; the perennial problem of choosing the best type of detector for a particular application. With the advent of multisensor detectors, photo, ion and heat sensors have been incorporated into a single unit. Independently, these different types of sensors have conflicting conclusions concerning the same environmental conditions. When they are combined in a single smart detector however, they can be monitored over time, reducing the chance of the device reacting to the wrong set of circumstances.
This is where the system's sophistication comes into play. True multisensor detectors compare values received form the onboard independent sensors to a preset algorithm. The device's microprocessor can then determine whether there is an actual danger, or if one of the senors is reacting to a nonthreatening environmental condition, such as dust or humidity. This data filtering process means the detector will only initiate an alarm when conditions match the characteristics of a fire exactly.
Refinements simplify installation and maintenance
While all of this marks a great leap in the dependability of fire alarm systems, refinements as complex as this raise serious questions about how far technology has brought the industry, and where it will eventually lead. As technology becomes more sophisticated, so must its application. Installing and maintaining these systems requires a higher level of skill than ever before.
Developers have begun to turn their attentions to refining what already works, and customers themselves are exhibiting more know-how when it comes to assessing new equipment. Today's customers are less likely to be dazzled by the technology and more inclined to question its place if the system is made unduly complicated. They are demanding a sophisticated system which is amply tempered for ease of use.
Manufacturers are listening. New software streamlines system set-up and verification, mimicking the familiar Windows interface. Control panels are becoming easier to operate. Touchscreens offering graphical displays of building plans are rapidly replacing rows of buttons and switches.
Opportunities to merge with other building systems
The future of life safety is without a doubt inextricably entwined with the technology driving it. Approaches are constantly being reworked and reinvented. Some believe that all building systems will eventually merge into one almost organic circulatory system that consolidates HVAC, security, life safety and communications.
But wherever the industry goes, one thing is certain: people and property are a lot better protected that they were just a short time ago.
For more details contact Progressive Systems Technologies on tel: (011) 285 0056, or e-mail: pstjhb@mweb.co.za
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