Encoding Fire Systems

Fire protection and security, including mass notification, access control and surveillance, are natural candidates for systems that should be converged. For instance, when a fire alarm goes off, a number of security functions exist that are mandated by code, and in addition, there are functions that are not mandated but would enhance life safety. So, having the systems integrated makes sense from both practical and code-compliant reasons.

NFPA 72-2010 has been renamed “The National Fire Alarm and Signaling Code.” “Signaling” was added to the title to recognize integration of emergency notification systems with fire alarms. Past editions of the code allowed the emergency alert system to be used for other purposes, such as the public address system, but mandated that fire alarms must have the highest priority. The code now allows other emergencies to take precedence under certain limited conditions. A designated person at a local command center would originate the signal to transfer the system to a microphone, so verbal announcements could be made. The code does not permit it to be done automatically.

Fire alarm and security systems

If a particular smoke detector triggers an alarm, dampers, fan controls and smoke doors in the heating, ventilating and air conditioning (HVAC) system should be electronically activated to prevent the flow of smoke from entering unaffected areas. Fire doors might be locked to prevent the spread of the fire, and/or security doors might be unlocked to permit people to evacuate and/or firefighters to enter. Since it’s possible to know the location of a sensor that triggers an alarm, one can activate a voice message to instruct occupants to move away from that location.

As an example of integrating fire alarm systems with other building systems, NFPA 72 requires elevators to automatically switch to firefighters’ recall mode or be sent to an alternate floor, and the system might shut down the elevators completely prior to automatically activating sprinklers. All these actions and interactions can be programmed locally or remotely in the fire alarm control panel (FACP).

“There are two ways to send such commands: the old-fashioned way, with relays, and the modern way, with software,” said Tom Hammerberg, executive director of the Automatic Fire Alarm Association.

Systems such as Notifier’s Onyx Works are software-based. They communicate using proprietary protocols over Ethernet, which uses either a copper or fiber pair. Onyx Works can be loaded onto a computer that already runs building-management system software, or it can be run on a computer provided by Notifier as part of the system. That way, the condition of all parts of the fire alarm network can be monitored on a single computer screen.

Networks need to be fast and accurate. They need to clearly communicate important information. To accomplish this, there have to be multiple network loops. Various sensors and manual pull stations report back to the FACP and initiate a preprogrammed response. To take advantage of modern networking technology, ideally there should be a fast Ethernet local area network connection and probably wide area network and Internet connectivity.

The major alarm companies, such as Honeywell’s Notifier and Gamewell/FCI; Siemens Industry USA’s Building Technologies; Tyco’s SimplexGrinnell; and GE Security, all provide systems that can be networked.

While the components of the fire alarm system can be easily networked, a gateway is needed to connect the fire alarm system to the building automation system. For example, using a BACnet or Modbus gateway, closed-circuit television (CCTV) surveillance cameras can be switched from intermittent to live coverage, and the lighting control system can be commanded to set all lights to maximum.

Implementing convergence

The technology for integrating fire alarms with building systems is not very different than for other systems, but actually implementing it is more difficult because of its critical nature. Fire alarms are more closely regulated by code, and since they involve life safety, the interaction with other systems has to be controlled very carefully. Therefore, experienced experts must do the integration.

“We integrate on a daily basis using BACNet, RS-232 and other protocols,” said Rodger Reiswig, SET, director, industry relations, SimplexGrinnell. “We routinely integrate to elevator controllers, lighting, HVAC, security CCTV cameras and access control systems,” Reiswig said. He went on to say that this is especially common for detention facilities, hospitals and college campuses.

Larger engineered systems distributors often handle integration. Companies such as Johnson Controls and Panduit also often handle it. Johnson Controls offers complete packages based on its Metasys building automation control system, ranging from designing the overall building management system, including fire alarms and emergency messaging, obtaining the components, and guaranteeing the ultimate system performance.

As with any building system, proper commissioning, regular testing and maintenance is key. For integrating fire alarm systems, however, the code mandates regular testing and maintenance.

BROWN is an electrical engineer, technical writer and editor. For many years, he designed high-power electronics systems for industry, research laboratories and government. Reach him at ebeditor@gmail.com or www.writingengineer.com, an independent professional writing service.

About the Author

Edward Brown

IBS Columnist and Freelance Writer
Edward Brown is an electrical engineer, freelance writer and editor who draws on his years of practical experience designing industrial processing and high-power electronics systems. In addition to writing the Integrated Building Systems column for E...

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