What is a Temporal-3 System?

MeyerFire University | FA304.01

By Al Yakel, SET

RESOURCES

• One-Page Summary [PDF]
• Notes Page [PDF]

CODE & STANDARD REFERENCES

• NFPA 72 – 2022: 18.4.2.1 Fire Alarm Signal to be distinctive in sound and not used for any other purpose
• IFC – 2021: Section 907.5.2.1 Audible Alarm required to emit a “distinctive” sound unique to fire alarm

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TRANSCRIPT

What is Temporal-3 System? 

NTRODUCTION

In this series, we will be discussing the different types of fire alarm system notification. To kick off the series, we will discuss the most common type of notification in the industry, temporal code 3. 

What you just heard is the standard alarm evacuation signal from smoke alarm which is now used internationally to indicate the need for evacuation. The signal consists of a three-pulse temporal pattern which meets the American National Standards Institute Standard S3.41. 

The S3.41 standard was developed in 1987 and became part of the National Fire Alarm Code on July 1st of 1996. Prior to the adoption of this standard, most fire alarm systems had a constant steady sound generated by bells or mechanical horns.  

IFC

IFC Section 907.5.2.1 requires audible alarm notification appliances to emit a distinctive sound that shall not be used for any other purpose. 

NFPA 72

NFPA 72 Section 18.4.2.1 defines a distinctive evacuation signal as a standard alarm evacuation signal consisting of a three-pulse temporal pattern in accordance with ANSI S3.41. 

THE PULSE

Three pulses with a half second on phase and a half second off phase followed by a one and a half second delay off phase, it doesn’t matter if it is a bell: (bell sound)

A chime: (chime sound)

Or the most common, a horn: (horn sound)

Regardless of the type of notification appliance, the temporal code 3 signal shall be repeated until the fire alarm system is manually silenced or reset by authorized or emergency personnel. The minimum signal duration is 180 seconds.  

The national fire alarm code does allow interruption of the signal for mass notification messages which is a topic we will discuss later in our series on notification appliances. 

TEMPORAL-3 (HORN/STROBE) & EMERGENCY VOICE/ALARM COMMUNICATION (VOICE OR EVACS)

Fire alarm systems have two methods for notification – temporal-3 and voice. Systems that exclusively use the temporal-3 pattern are usually called horn/strobe systems. This is a traditional commercial-type fire alarm system.  

The other type of fire alarm systems use voice, and are called emergency voice/alarm communication systems or voice systems. Evacs system will use the temporal-3 pattern and voice instruction in the messaging. These are slightly more complex systems that make use of speakers instead of horns. We’ll talk about those in the next segment.

SUMMARY

In summary, temporal code 3 is the standard evacuation signal used throughout the world to indicate the need to evacuate. All fire alarm notification appliances including horns, horn/strobes, bells, chimes or even speakers must initiate this signal upon alarm activation throughout the building or notification zone and maintain the signal until it is manually silenced or reset by authorized or emergency personnel.  

If you are in a building and you hear the three pulses calmly make your way to the nearest exit and if in a multi-story building, do not use the elevator… 

In our next video, we will discuss emergency voice evacuation systems or evacs system. 

Until next time, I am Al Yakel and this is MeyerFire University.