Is Fire Networking Ready for Prime Time?
The emergence of network-like technology in the fire alarm industry is already underway. Although progress is somewhat slow and the degree of implementation varies from manufacturer to manufacturer, overall the industry is moving in the direction of a network-based solution with information technology (IT) clearly in view. A handful of fire equipment manufacturers have recently given us a peek at what tomorrow’s fire alarm network might look like. Although no one can render an exact prediction, I believe it’s safe to say some resemblance to traditional IT is assured simply because it represents one of the most logical and efficient ways the industry can better accomplish its life-safety goals.
The idea of using existing network resources with an already installed cable infrastructure makes perfect sense, but it is not quite ready for field use. The fact is before LAN involvement can take place in the fire alarm trade, major changes in IT must occur. Until then, fire technicians and their clients will have to settle for a network-like environment where fire alarm equipment manufacturers utilize manageable elements contained within the IT realm.
Why LAN Involvement Is Limited
One of the most significant hurdles IT/fire alarm proponents must jump involves the issue of fire codes and listings. In order for FM, UL and the National Fire Protection Association (NFPA) to sign on to the use of conventional network technology, certain things will have to be addressed.
“There is no technical difficulty with the implementation of an Ethernet-based network today as fire alarm data communication is the same as IT data. The main problem is in regulatory concerns such as National Fire Protection Association, Factory Mutual and Underwriters Laboratories requirements,” says Dick Aldrich of Gamewell-FCI by Honeywell.
One issue that impedes the use of IT in fire alarm systems involves fault-tolerant technology — or the lack thereof in this case. Although there are ways to build fault tolerance into today’s LANs, the cost of implementation can be prohibitive. And a relatively large percentage of fire officials continue to see fire detection in a more traditional sense. Many of these inspectors are likely to disallow the use of traditional network technology where it involves transporting critical fire alarm and trouble data.
The other aspect of this involves the issue of network technology itself. For example, in a traditional Style 6 signaling line circuit (SLC), NFPA 72 detection is to take place even when a single open or ground condition exists. Style 7 SLCs must achieve this, plus operate in the face of a wire-to-wire short, all without missing a single beat. It’s not that it could not be done, but it’s not yet realistic to expect a traditional LAN to achieve the same level of survivability as a common code-compliant fire alarm system.
Another problem network technology faces is transmission distance. The allowable distance between network nodes in a typical LAN is approximately 300 feet, whereas a common fire alarm system can transmit signals for several thousand feet.
Today’s Fire Detection Network
Although the fire industry cannot yet use a building LAN for critical fire detection and command and control functions, there are aspects of network technology the fire alarm industry can use. This is especially true of high-end fire alarm systems, often referred to as enterprise-grade systems. But perhaps the first order of business is to develop standards within the fire alarm industry itself, which would make the advent of IT in this arena more likely.
“The fire alarm industry has not yet agreed upon and established an acceptable standard covering modern networking technologies. Those manufacturers delving into distributed networked systems have all developed proprietary networks and protocols. Performance of these networks varies as much as the data communication rates which span from 9,600 baud to 1 megabit,” says Aldrich.
In the case of Gamewell-FCI, its network infrastructure relies on a two-conductor configuration. A single pair of wires allows fire technicians to carry detection signals right alongside emergency voice alarm communication (EVAC) information, system status data, and more.
Digital Security Controls (DSC) of Concord, Ontario, Canada, produces a commercial fire panel called the MaxSys that incorporates a network-style data bus (called a combus by DSC). In much the same way routers and switches can be placed on an Ethernet circuit, DSC provides input/output (I/O) modules that can be connected to the combus to perform a variety of tasks. Power supplies to relay output modules, keypads to zone expanders, these modules can be connected to this common data circuit to receive command and control signals. The technology itself is also built on distributed intelligence where local fire control nodes (panels) are used to manage fire safety functions right along with EVAC and detection. The benefits associated with this approach include advanced survivability. Here each node continues to operate as programmed event when communication with the head-end (fire alarm panel) is severed. This is a common occurrence in times of emergency, such as electrical storms or an explosion.
Interconnecting With Networks
There are times when it’s possible to bring traditional network technology into a fire alarm environment. “Fire manufacturers are trying to come up with ways to use [conventional] network technology that relates to Ethernet-based TCP/IP, even the Internet. But in most cases you will find hybrid systems where they use technologies between 9,600kbps and 1Mbps data rates, and they somehow use a gateway to tie it to a PC,” says Aldrich.
The use of conventional network technology to monitor fire alarm status and real-time functions does not violate NFPA 72 or 101. That’s because the PC or network head-end is not in control of fire detection. “The primary command and control remains within the FACP [fire alarm control panel] as of today and the Ethernet-based TCP/IP connected equipment is relegated to the classification of auxiliary controls,” says Aldrich.
LAN technology can be used to monitor the status of fire alarm control panels as long as critical functions continue unimpeded by faults and other problems that may occur on the LAN side of the I/O interface.
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