Fire Protection

Shaping-Up Surveillance

Advent of technologies doesn't mean tried-and-true techniques are all washed up

• By Tom Hauder
• Sep 01, 2006

ALTHOUGH smoke detection in homes and commercial buildings has been in use since the 1960s, there have been few significant advancements in the technology until recently. With the advent of newer technologies that combine fire and smoke detection methods, it seems many of the staple technologies of the industry, such as photoelectric detectors and beam detectors, are being seen as less effective, because of the limited sensing technologies.

Developers of photoelectric smoke detectors have recently added features that help extend the life of the detector and cut down on the chance of a false alarm.

These tried-and-true smoke-detection techniques are still effective for applications, such as spot and area smoke detection. The modifications that have taken place inside the detector within the past few years have radically changed standard technologies while bringing new innovations to the table.

A trend in the fire detection and safety industry -- especially in commercial, business and residential applications -- is the desire for aesthically-pleasing detectors designed to blend in with the architectural integrity of a building or facility. These significant changes, stemming from both the detectors themselves, as well as from market demands, have led to the recent advancements in smoke-detection technologies.

Breaking Down the Industry's Ion
The ionization detector, which once was the detector of choice, has lost popularity in recent years, especially in commercial applications, for two important reasons: false alarms and environmental concerns. The ionization detector excels at catching fast-flaming fires, but is susceptible to detecting elements in the environment that are not smoke, leading to numerous false alarms. The principal of operation has only changed slightly in the many years since its invention, and the ionization detector is still more prone to false alarms than comparable technologies.

From an environmental perspective, although the ionization detector contains a small amount of radioactive material (Americium 241), in order for the detection chamber to work, there is still concern surrounding the manufacture and disposal of the detectors. Even though the radioactive material is considered a low alpha emitter, it is safely trapped in a gold matrix. Public concern surrounding this type of material makes the ionization detector a very unpopular choice. Since safer options are available, several smoke detector manufacturers have eliminated ionization detectors from product lines.

A Lighter Approach to Smoke Detection
With its advances in technology, photoelectric smoke detection has come to dominate many of the detector designs in commercial applications.

Early photoelectric smoke detectors were primarily used in tandem with ionization detectors, since the two different types of detection covered the whole range of particle size: photoelectric for smoldering-type fires and ionization for flaming fires. But the technology of today's photoelectric chambers provide a detection range very close to ionization characteristics.

Developers of photoelectric smoke detectors have recently added features that help extend the life of the detector and cut down on the chance of a false alarm. The new, drift-compensation function that offsets dirt build-up in a detector chamber, allowing the chamber to accurately detect smoke for a longer service life than ever before, is just one example. Previously, as dirt would collect in a non-compensated chamber, the detector's sensitivity would increase and eventually set off a false alarm. In the new, compensated detector, the chamber adjusts for contamination and can stay in service for a much longer period. And when the chamber gets too dirty to be compensated, many detectors can signal the panel for service instead of triggering a false alarm.

The combination of photoelectric detection technology with other technologies, such as heat or carbon monoxide (CO), is another advancement in smoke detection technology that helps cut down on false alarms. One example of this combined technology is Bosch's FCP-500-C smoke detector, which integrates a CO element used solely for the purpose of false alarm rejection. By using the presence or absence of CO, the detector can adjust its sensitivity to rapidly capture a true fire, but reject other types of interference, such as steam, cooking smoke and airborne pollutants from chemicals and sprays that would normally cause a false alarm.

Advances in smoke detection have come a long way, especially on the inside of the detector, and false-alarm rates from equipment malfunction or contamination have dramatically improved. Still, some end users will balk at having active fire protection because of cost or impact on the looks of the covered space. This is where some newer, alternative technologies can provide additional benefits.

New Detectors Beam with Results
Because early beam detectors were bulky, difficult to install and hard to keep aligned and in service, this method of smoke detection has not always received the attention it deserves as a cost-effective, unobtrusive method of smoke detection.

Beam detection now comes housed in a variety of small packages. When it comes to protecting large, open areas, such as auditoriums and gymnasiums, it's tough to beat beam detectors for coverage per dollar and minimal visual impact. Newer reflective models employ only one transceiver and a reflective panel, making the units even more unobtrusive in the space versus standard beam detectors that have a box of electronics at both ends, such as a transmitter and receiver hooked together. In addition, alignment, the most difficult part of keeping a beam detector working, has undergone dramatic improvements that enable beam detectors to be used as "set and forget" detectors.

Spotting the Benefits of Newer Technology
Flush-mount, spot detectors that improve system aesthetics while maintaining the quality of the system have recently been developed. These new detectors have no physical chambers mounted to the ceiling, and only a smooth plastic plate is visible. Flush-mount detectors can operate and are specified like standard, spot-smoke detectors. This type of detection lends itself well to environments where architectural integrity is a concern, such as in hotels, upscale apartment complexes and corporate offices.

Bringing Fire, Safety Closer Together
One of the most recent changes in smoke detection methods doesn't necessarily involve the advancement of detection technologies, but rather the incorporation of a different security measures to help in smoke and fire detection. By integrating standard CCTV cameras into a system to help monitor smoke and flames, users gain an added visual perspective to the nature of the fire. Several cameras can cover a wide area and provide both fire and security coverage. The combined fire and safety technology is proving especially useful in areas not typically manned by security personnel, including transportation tunnels, train stations and fuel depots.

As technologies advance and techniques combine, the smoke detection industry continues to improve its products. So, when specifying or designing a fire alarm system in the future, be sure to check the advantages of new technologies for a specific application to see how design, and ultimately the level of fire safety, will benefit.