21st century fire safety

Building Operating Management, May 2000 by Carrigan, Jim

Advances in technology have produced reliable, intelligent fire safety systems that have the flexibility to meet a wide range of facility needs

UNTIL THE EARLY PART of the 20th century, building fire alarm systems consisted of human occupants with sensitive noses and booming voices. Unfortunately, they could not prevent the tragedies that eventually prompted development of uniform building codes and standards requiring electromechanical fire alarm systems. The first was a conventional, 110-plus volts fire alarm system comprising manual pull stations and bells, which remained "state of the art" through the 1960s. Today, intelligent analog addressable systems provide owners with unsurpassed reliability and flexibility.

First, let's take a look at some of the milestones in the development of sophisticated fire alarm systems. These are pertinent not only from a historical viewpoint, but also because older systems are still in use today.

The first early warning devices were high-voltage smoke detectors, which were incorporated into existing conventional, highvoltage fire alarm systems in a separate system connected to the bell circuits.

Next came multiplex system. These "modern" fire alarm systems allowed the distribution of system transponders which decreased riser cable quantities. However, like the conventional systems, multiplex systems require a separate circuit or zone for each type of device. A detection device sets off a zone alarm, yet the precise source of the alarm can only be identified by searching the area.

A real milestone was the development of addressable systems in the mid- to late1980s. Addressable systems comprise multiple "intelligent" devices - pull stations, smoke detectors, heat detectors, etc. - on a single circuit. , These systems not only pinpoint an alarm source on the control panel, they also substantially reduce the amount of wiring required for installation.

Today's analog addressable systems have an even "higher IQ" than their parents. Not only are they reliable and flexible for customized applications, they also allow sensitivity-adjustable devices to be adjusted from the control panel. These devices are beneficial in reducing nuisance alarms from food storage or dusty environments. Analog addressable systems are recommended for virtually all applications.

Many other developments are now standard features of today's systems:

* Low voltage systems. Introduced as 12v or 24v DC multiplex systems, these systems eliminate the need for conduit on field circuit installations in many jurisdictions, dramatically reducing the time and cost of installation.

* Combination devices. Integrated smoke and heat detectors cost less than buying and wiring two individual devices.

* Central station transmitters. A microprocessor-based transmitter, usually connected to two dedicated building telephone lines, transmits information from Il,the fire alarm system to a central station service, which relays it to the fire department, identifying the source of the alarm in the building. Point annunciation can also enhance the fire department's response.

* Network and campus-type fire alarm systems. Standalone systems can be networked into one or more central monitoring locations serving a multiple-building campus. These systems can enhance the response of fire safety personnel, while making semi-annual maintenance easier.

* Graphic and remote annunciators. Particularly beneficial in large buildings or a campus setting, graphic annunciators display the building floor plan on a CRT when an alarm sounds, highlighting the exact device in alarm on the CRT. This can be printed out and given to fire fighters.

* Self-diagnostics. Analog addressable systems indicate devices that are dirty and reaching an alarm threshold. This enables the owner to spend maintenance dollars where they really count.

* Wireless systems. Obviously, their development was a milestone, with the potential to produce dramatic savings in installation. However, they are subject to many sources of radio frequency type interference. Battery maintenance is high and supervision is not as reliable when compared to a hard-wired system. They are not approved by many jurisdictions.

Liabilities of Old Systems

It is still very common today to find 30- to 40-year-old conventional high-voltage systems in use. These old systems have a lot of liabilities, both practical and legal. First and foremost, these systems are outdated and do not match the level of life safety of the newer systems. Available maintenance is costly because few companies support these systems; parts, if they are available, rarely carry the UL seal.

Most of the multiplex systems installed in the 1970s and '80s are still operational. These are maintenance problems as well. Fortunately, some manufacturers' new systems maintain a level of "backward compatibility" with multiplex-type systems, enabling an owner to phase an upgrade, based on budget constraints.

In either case, there usually are creative ways to phase in upgrades. Consider a current project in a facility with a 40-year-old high-voltage system. Because there is no budget to upgrade all buildings at once, a phased replacement has been proposed to coincide with the modernization. A new infrastructure will be installed now for the fire alarm system, but individual floors will not be fitted out with devices until renovations begin.