FIRE ALARM SYSTEMThe Basics

NFPA 72 National Fire Alarm Code® 2007Not a Code unless adapted by AHJ

NFPA 101 Life Safety Code® 2006Not a Code unless adapted by AHJ

FIRE ALARM SYSTEM

NFPA 101 Life Safety Code®2006 “The purpose of the code is to provide minimum

requirements, with regard to function, for the design, operation and maintenance of buildings or structures for safety of life from fire”

This is accomplished by: 1.) Protection of occupants not intimate with the

Initial fire development 2.) Improvement of the survivability of occupants intimate

with the initial fire development.

FIRE ALARM SYSTEM

NFPA 72 “The purpose of this code is to define the

means of signal initiation, transmission, notification, and annunciation; the levels of performance; and the reliability of the various types of fire alarm systems.”

“The purpose of fire alarm systems shall be primarily to provide notification of fire alarm, supervisory, and trouble conditions; to alert the occupants; to summon aid; and to control fire safety functions.”

Audible Signaling Terminology

dBFrequencydBAAmbient Noise

Audible Signaling Terminology

dB= Measurement of loudnessFrequency= Pitch, Bass vs High pitch squealNarrow Band= A small range of frequencies- usually called an octave banddBA= Loudness measurement adjusted to how we hear and perceive the relative loudness of different frequenciesAmbient Noise- The normal sounds during normal occupancy. Not temporary sounds.

Notification Terminology

SignalingArouse/AlertNotificationInformation

Notification-How?

Use the human senses Visual- Previously

discussed Audible Other

Audible System Goals

How loud must the fire alarm be for the given noise information? NFPA 72.4 Audible Characteristics

Public Mode Audible Req.

NFPA 72.4.2.1 15dB above average ambient sound 5dB above maximum sound level of

60 seconds.

Private Mode Audible Req.

Private mode-Staff is part of the overall fire protection strategy Minimize fire alarm Use voice Combine systems Text Messaging Eliminate audible tones and voice in

some areas

Sleeping Area Req.

NFPA 72.4.4.1 Public mode Requirements or 75dBA minimum

Whichever is greater

Sound Attentuation

Sound is measured in dBA which is logarithmic scale Double distance= reduction of ½ of

sound pressure (or 6dB)

Design of Audible Signaling

Distance Sound level(from device) (dBA) 10’ 95dB

20’ 89dB40’ 83dB80’ 77dB

Design of Audible Signaling

Using fewer appliances results in some locations being very loud.Using more appliances at a lower level results in even distribution without loud spots.

Next Presentation

Audible Signaling Noise Coefficients (NC) Sound Transmission Coefficients

(STC) Locating devices. Initiation Basics

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