High-Rise Buildings Call for High Safety Standards
To firefighters, just as the tenants of a high-rise structure, time is of utmost importance when a fire breaks out. According to experts, if fire department response is 15 minutes or more in this type of setting, it’s likely that the fire will quickly advance to where firefighters can only control the burn from inside the stairways. “After 15 minutes of response time for a fire in a high-rise building, firefighters may discover the fire is too large to extinguish. The fire spreads out of the room along the ceiling and forces them to withdraw off the floor out into the stair enclosure” (Iklim Ltd. STI, an Ankara, Turkey-based contractor, www.iklimnet.com).
Therefore, it is imperative that the fire alarm control panel in a high-rise building quickly detect developing fires, interface properly with fire safety protection systems and notify a central station or remote supervising station of some kind as quickly as possible so firefighters can be swiftly dispatched to the scene. Panels Control Safety Functions
Historically, the proper operation of fire safety systems is of special importance to the high-rise community when a fire takes place. The alarm control panel used in this setting must be capable of full or partial integration with the various fire protection functions. “One of the most important aspects of installing fire alarm systems in high-rise buildings is the interface of fire safety control systems with the fire alarm control panel,” says Tim Creenan, fire engineer with Amherst Alarm Inc. of Amherst, N.Y.
Fire safety functions involve a number of systems that act together to increase the chances of survival among the occupant/resident population. “Examples include door holders, HVAC shutdown, smoke dampers and smoke control systems,” says Creenan. The idea is to quickly and efficiently compartmentalize such a facility when a fire is detected. Electric door holders are designed to automatically close when a fire is detected. Fire dampers contained in ductwork must also be closed to limit the future spread of smoke. Additional fire safety functions often include stair pressurization equipment; the unlocking of stairway doors to allow rapid, ready egress; the control of emergency lighting; and the deactivation of electric locking mechanisms as found in access control and other types of door control systems.
Provisions and properly engineered and listed hardware must be inherent in the fire alarm control panel in order to make all of these things happen. HVAC, Smoke Control Is Imperative
Another aspect associated with control panel design and performance is HVAC system control. Systems contained in a typical high rise must either be shut down or reversed in order to remove smoke, all of which must be part of the integral design of the HVAC system.
Frankly, if a failure should occur between the control panel outputs and the HVAC system, wholesale death and injury can easily result, as took place at the MGM Grand hotel and casino in Las Vegas in 1980.
“It was just after 7 a.m.; they (the tenants) might have been asleep, still groggy. They may have retained a semblance of calm, awaiting rescue. But they were doomed anyway, doomed by the very thing that made mass tourism possible in Las Vegas: air conditioning. It filtered out the smoke but pumped deadly carbon monoxide, a silent killer, into their rooms” (www.iklimnet.com).
The MGM fire resulted in 84 deaths, 679 injuries and more than $300 million in property damage. It also changed the way high-rise buildings are constructed and how fire protection systems are installed.
To assure the proper operation of inherent fire safety functions, a fire alarm control panel must be equipped with a number of auxiliary relays, usually made available by output modules that come with one, four, eight or more Form C relays. Using the right relay module is also important so the relay contacts provide the correct current carrying capacity. When dealing with a common control circuit in another building subsystem, such as a fan or HVAC controller, a low-current relay will usually suffice. A heavy-duty relay module, however, is required when a relatively large current must be controlled, as is often the case when supplying power to a fan motor or controlling emergency lighting. Voice Evacuation Required by Code
According to NFPA 101, 2000 Edition, high-rise buildings require the use of a voice evacuation system. Section 18.104.22.168 says, “A fire alarm system using an approved, emergency voice/alarm communication system shall be installed in accordance with Section 9.6.”
Creenan says when voice evac is part of the fire alarm control panel design, the software programming includes features you may not realize with the add-on approach. One example is the ability to send different messages to different floors based on input from field devices.
“Such special programming features include the ability to send one message to the occupants on the floors below and above and still another message to those on the floor where the fire is,” he says.
This capability is valuable in situations where the situation does not warrant evacuating everyone in the building. It’s also possible to order the evacuation of the occupants in a gradual manner, avoiding injury and death in congested, packed stairways and hallways.
Add-on voice evacuation systems are also available for retrofit applications. This is especially helpful when working with existing fire alarm systems that are still viable and not yet in need of replacement. In this case, the audible portion of the system’s conventional notification appliance devices must be converted into audio circuits with speaker notification devices.
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