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From NFPA 72, 2002 Edition: “7.4.2.1* To ensure that audible public mode signals are clearly heard, unless otherwise permitted by 7.4.2.2 through 7.4.2.5, they shall have a sound level at least 15 dB above the average ambient sound level or 5 dB above the maximum sound level having a duration of at least 60 seconds, whichever is greater ...
an alarm clock that sounds an alarm at a pre-set time, often used to wake a person up or remind them of an event. a fire alarm which is used to give occupants of a building early warning of a potential fire and give them time to evacuate. warning devices on a vehicle that sound when it is moving in an unexpected direction, such as reversing,
A fire alarm control panel Fire alarm speaker and pull station. Fire alarm systems are composed of several distinct parts: Fire alarm control panel (FACP), or fire alarm control unit (FACU): This component, the hub of the system, monitors inputs and system integrity, controls outputs, and transmits information.
When the box is activated by turning a knob or pulling a hook, a spring-loaded wheel turns, tapping out a pulsed electrical signal corresponding to the box's number. [1] A receiver at fire headquarters announces the alarm through flashing lights or tones, or via a pen recorder, and the box number is matched to a list of box locations.
Many modern fire alarm pull stations are single-action and only require the user to pull down a handle to sound the alarm. Other fire alarm pull stations are dual-action, and as such require the user to perform a second task before pulling down, such as lifting or pushing in a panel on the station or breaking a glass panel with an attached hammer.
In the United States, the National Fire Protection Association sets standards for PASS devices in NFPA 1982. [ 1 ] The PASS device is normally used in conjunction with breathing apparatus; it is a small, battery-powered device attached to the self-contained breathing apparatus (SCBA) harness which enables the firefighter to summon help by ...
However, in most fielded systems, unwanted clutter and interference sources mean that the noise level changes both spatially and temporally. In this case, a changing threshold can be used, where the threshold level is raised and lowered to maintain a constant probability of false alarm. This is known as constant false alarm rate (CFAR) detection.
The system uses a distinctive "WHOOP" tone that was originally produced for Federal Signal's line of fire alarms. The system is tested on the second Monday of every month at 6:00pm. [6] Alaska has many Federal Signal Modulators and Eclipse 8s on their All Hazard Siren System. They sound for tsunamis as well.