Emergency Communications

When most of us in the fire alarm industry think of MNS we think one-way communications. The truth of the matter is, under NFPA 72, 2010, and in real practice, there are two types of emergency communications systems (ECS): one- and two-way.

One-way systems usually involve the use of audible/visual notification means, such as horn/strobes, strobe-only or speakers. MNS also includes textual displays (e.g. LCD text board) where messages can display the status of critical systems as well as provide important MNS commands.

As an example where one-way communication can be beneficial, when a fire breaks out on the 12th floor of a 24-story high-rise, it may not be practical or advisable to evacuate the entire building at the same time. Instead, a one-way EVAC system can assist management, firefighters and other first responders by allowing them to deal with occupants in real-time. In many cases this would be done on a floor-by-floor basis, beginning with those above and below.

MNS is all about conveying specific information to the right spots through verbal and textual means. As to the use of strobes and other traditional single-output devices: “This Section does not apply to bells, horns, or other sounders and lights except where used in conjunction with the desired operation of emergency messages and signaling” (A24.3.6, NFPA 72, 2010).

Two-way communication systems allow both building occupants and firefighters to communicate in a number of ways. For example, firefighter phones provide first responders a means of communication on a floor-by-floor basis. This is especially helpful when traditional radios cannot penetrate throughout a structure, most often due to metal content within walls.

An area of rescue assistance intercom is a good example of a two-way communication system designed so handicapped occupants can obtain a means of escape from the upper floors of a building. This is more desirable than attempting to remove them while evacuating the more mobile occupants of a building.

“Two-way emergency communications systems are used to both exchange information and to communicate information such as, but not limited to, instructions, acknowledgement of receipt of messages, condition of local environment, condition of persons, and to give assurance that help is on its way” (A24.3.6, NFPA 72, 2010).

The Need for Integration

Integration between traditional fire alarm EVAC systems and MNS is an important part of UFC and NFPA 72, 2010. Through integration it’s possible to assure safety and successful passage of occupants during emergency situations. Integration is necessary so messages are clear and concise – without conflict.

During an event the last thing authorities want is the fire alarm system to say one thing and the MNS to say another. A good example of this is where an EVAC system attempts to evacuate the building and an MNS component instructs people in specific areas to proceed to a safe area within a building.

Another example where fire alarm technicians may take exception is in the area of precedence. UFC and NFPA 72, 2010, both stipulate MNS take priority over fire alarms.

“The communications systems shall be capable of interfacing with existing fire alarm systems, existing PA systems, and existing telephone dialing systems on the DoD installation. The communications systems shall be designed with an established protocol that is provided to the DoD installation to allow existing and future individual building MNS from other manufacturers to interface with the wide area MNS. The wide area MNS manufacturer shall provide a standard interface method (such as an audio line-level output and multiple relay contacts) or supply the necessary digital communication protocols to permit the DoD installation to select more than one manufacturer of individual building MNS” (Section 3-7.6, UFC 4-021-01, 9 April 2008 Revision).

In order to do this, fire alarm manufacturers, such as Honeywell, Simplex, ADT and others, have worked to create an integrated platform through which both functions can work without conflict, especially where both functions activate at the same time.

Al Colombo is a technical writer in the electronic security and fire protection markets, providing technical direction for security dealers since 1986. Al has held a number of positions within the security and life-safety markets over a period of 32 years.

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