Thursday, July 31, 2008

Fire Detection and Life Safety: The PAST and Future Progress

Since the birth of the fire alarm industry in 1852 in Boston when the first municipal fire telegraph system was put into operation, an industry concerned with saving lives and reducing property loss was soon looking to expand and improve on this much anticipated device. The first municipal electric alarm system incorporated call boxes and automatic signaling, ushering in a profound change from hand-held clackers running through the streets and bell ringers perched in church steeples on watch for fires. A look at what has taken place over the last 30 years has been just as astonishing as the industry made a quantum leap from low-intelligence systems just a few decades ago.

Since the 1970s, when the industry relied on the technology of switcher and relay controls, which incorporated "big, old" electric relays, similar to an on/off switch, this low intelligence design was soon headed for a makeover. "Prior to the 1970s everything was still working off revised older technology, the relay operated systems," said Ralph Sevinor, president of Wayne Alarm Systems, in Lynn, Mass.

During this decade, digital alarm communication transmitters (DACT), discrete and solid state components were introduced, providing expanded use of a new feature to the fire alarm called zoning. "Up until this point zoning was being introduced only in very large applications and the technology was fraught with problems in many instances." According to Sevinor problems existed such as the wiring in the walls receiving signals of all kinds either real or conducted from the airwaves back to the main panel. "All the wiring that had to be there for the horns, smoke and heat detectors turned out to increase conductivity, especially during lightning storms when surges would happen."

Historically, the advancements in fire alarm systems have often been the result of a tragedy, where lives and property could not be saved. "This is a code driven industry, unlike the security industry, when there is a major tragedy it creates a knee-jerk reaction to fix what could have been mitigated or to correct what went wrong," stated Sevinor. An example of this reaction he said can be traced back to the 1970s when regulations in many states mandated that there be heat detectors and smoke detectors in closets and bathrooms in residential housing. "This was a great idea at the time as the theory was to catch the fire early enough to allow for the residents to get out safely and contain the incident. Unfortunately, the technology at the time employed ionized detectors and every time a resident turned on the hot water or took a shower, a plume of steam would trip the smoke detectors," he explained. As a result, he said, what was anticipated to be a life saving device actually created widespread false alarms. Now, the industry hadn't solved the problem it set out to but instead created another.
When microprocessors were introduced into the computer industry, the advancement was seen as possibly benefiting other industries as well. "The industry went from the old relay controls to solid state to microprocessors which opened a whole new world," explained Steven Rossi, vice president of Communications for Honeywell Fire Systems, Northford, Conn. The world's first single chip microprocessor introduced by Intel in 1971 was within months developing marketing plans to encourage other applications for the new invention which could perform hundreds of millions of calculations each second. The fire alarm industry eagerly embraced this advancement.

Industry experts agree the biggest change in fire alarm technology happened when microprocessing increased the intelligence in the fire panel. "Without a doubt the addressability of the fire alarm has been a big step forward," stated Rossi. The future continues to look bright as manufacturers offer more features. "We can actually watch the migration path of a fire on a monitor," he added. "We can look at the map overlay and relay information back to the fire fighters alerting them to potential additional hazards they may encounter. Firemen no longer have to pull up to a building, unaware of what is in their path."

Heat and smoke detectors
These devices began gaining in popularity as life saving tools beginning in the late 1960s. "As a result of tragedy, the codes were changed and the emphasis on life safety grew, as it should," said Richard Kleinman, president, of AFA Protective Systems located in Syosset, N.Y.
"Smoke detectors are much more efficient than they were long ago," said Mike Henke, product manager for the Sprinkler Division of Potter Electric Signal in St. Louis. "They are less prone to false alarms because they incorporate photoelectric and better ionization features." Kleinman concurred, "The technology behind the smoke detector has changed. There is greater sensitivity for the various types of smoke that can be detected and the pinpointing of the location of smoke has been enhanced."

Sprinkler systems
The concept is a fairly straight-forward one: a heat-sensitive element that opens and sprays water. "The sprinkler system was designed for property protection," said Kleinman. When the sprinkler system lets go and the water is released, a signal is sent to put out the fire and to limit the water damage. After all, following heat and smoke detectors this is the next line of defense in a fire. "A lot has happened over the last 30 years. The increase in the types of sprinklers has been ten-fold. Early models would have a soldered element that would heat up and melt away allowing the water to spray out," said Henke. While that particular model is still in operation today, Henke said the choices in performance are nearly endless with quicker opening sprinkler heads to extended spray heads to meet the demands for many applications.
Sprinkler design and performance has benefited from being tweaked over the years and available options set them apart from their earlier counterparts. "Sprinklers can now spray an array of either small or large droplets depending on the type of fire; they can also spray in a particular pattern and the response time has increased allowing for earlier egress," added Henke.
Where the industry is headed will include improvements such fewer false alarms, increased compatibility with other building controls and increased communication capabilities between the fire panel and the central station.

"In the future I see more microprocessor control interfacing with the fire alarm which will communicate with the building's HVAC and air handling systems. I also see switching over to the Internet as the preferred method of communications over using phone lines,"

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