718 Fire Prevention Plans

Audible Alarms

Only temporal signals or voice signals are approved by NFPA 72 for new audible alarm systems because they are the most effective alarm systems.

Temporal Coded signals

Temporal coding is accomplished by interrupting a steady sound in the following manner:

• Use the following repeating cycle: .5 sec ON; .5 sec OFF; .5 sec ON; .5 sec OFF.
• Use a distinctive three-pulse temporal pattern to signal an immediate emergency evacuation. The signal must consist of a "three-pulse" temporal pattern described in ANSI/ASA S3.41, Audible Emergency Evacuation Signal, American National Standard Institute (ANSI)
• Only use this signal pattern to notify personnel of the need to immediately evacuate the building. Total evacuation is not always desirable or necessary during an emergency therefore there should be a different signal pattern assigned to signify the need for relocation of the occupants from the affected area to a safe area within the building or for a "shelter in place".

Voice Signals

A workplace announcement system using speakers can be used to play a live or recorded voice message. They are often ideally suited for large workplaces where phased or guided evacuations are needed.

Bells, Horns, and Sirens

The following bells, horns and sirens, are only permitted in existing systems. They are not approved for new systems.

• Bells: Vibrating bells are the most common signal device. Bells are commonly used in schools for fire alarms.
• Horns: Horns produce a very loud distinctive sound that immediately attracts attention. Horns can be useful to call attention to critical situations.
• Sirens: Sirens produce a loud piercing wail that makes them ideally suitable for initiating a site-wide evacuation.

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