fire alarm system_ne-audible_signaling[1]
TRANSCRIPT
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
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