Introduction
A Notification Appliance is any device that alerts building occupants of a fire or emergency through audible, visible, or tactile signals. These appliances are essential components of fire alarm systems, ensuring timely evacuation and awareness in emergencies.
This comprehensive guide explains the design, types, and best installation practices for all types of notification appliances used in modern fire alarm systems.
Types of Notification Appliances
1. Audible Notification Appliances
- Common types: Horns, Bells, Speakers, and Buzzers.
- Evacuation signal pattern: Temporal Three (T3) – three half-second pulses followed by a 1.5-second pause.
- For sleeping areas: low-frequency sound 520 Hz ±10% is recommended to awaken sleeping occupants.
- Sound level should be at least 15 dB above ambient noise or 5 dB above the maximum sound lasting 60 seconds.
2. Visible Notification Appliances (Strobes)
- Provide flashing light for hearing-impaired occupants.
- Light intensity measured in candela (cd) per room size and height.
- Mounting height: typically 80–96 inches (2.03–2.44 m) above floor.
- Multiple strobes in the same field of view should be synchronized.
3. Tactile Notification Appliances
Used for individuals with visual and auditory impairments, tactile devices vibrate to provide emergency alerts. Commonly used in sleeping areas of accessible facilities.
4. Textual and Graphical Notification Appliances
Include LED signs, displays, or monitors that show text or graphical evacuation messages. Often part of Mass Notification Systems (MNS).
Installation and Performance Requirements
- Use devices that are properly listed for fire alarm applications.
- Mounting height: place wall-mounted devices high enough for visibility/audibility while respecting ceiling clearances.
- Avoid mixing different tones in the same space to prevent confusion.
- Ensure uniform coverage—both audible and visible—throughout occupied areas.
Spacing and Synchronization Requirements
- Strobe placement and candela rating depend on room size and mounting height.
- Each occupant should see at least one strobe flash per activation cycle.
- All strobes in the same field of view should be synchronized.
Inspection and Testing
- Inspection: verify operation and location regularly.
- Testing: confirm SPL (sound) and candela (light) meet design values.
- Acceptance testing: perform before handover.
Practical Examples
- Stairwells and Exits: Horn/strobe units near each exit and stair enclosure.
- Sleeping Areas: Low-frequency 520 Hz sounders.
- Open Offices: Combo horn/strobe units.
- High-Noise Areas: High-candela strobes and supplemental tactile devices.
Conclusion
Correct selection, installation, and testing of notification appliances are essential for life safety. A well-designed system ensures clear, effective, and synchronized emergency alerts for all occupants.