A Guide to Fire Alarm Basics
A fire alarm system is a crucial part of the fire and life safety of a building and its occupants. There are many functions that are served by the fire alarm system and it all may be a bit confusing to someone new to fire alarms, so I decided to create a visual guide to fire alarm basics. The objective of this blog is to share that visual guide and to discuss some of the major components and functions of a fire alarm system.
FACU – Fire Alarm Control Unit
The fire alarm control unit serves as the brain of the fire alarm system by monitoring all the inputs and controlling all the outputs. Some may also refer to this as a fire alarm control panel or fire alarm panel. The different types of conditions that can be seen at the fire alarm control unit are Alarm, Supervisory, and Trouble, these conditions can also result in a signal being sent to the supervising station.
Alarm – An alarm condition means there is an immediate threat to life, property, or mission. An example of this would be a smoke detector sending a signal to the fire alarm control unit that there is a presence of smoke, which would initiate notification to the occupants to evacuate.
Trouble – A trouble condition means there is an issue or fault with the fire alarm system. An example would be a break in an initiating device circuit. This would show up as a trouble signal on the control unit.
Supervisory – A supervisory condition means there is an issue with a system, process, or equipment that is monitored by the fire alarm control unit (see supervision section). An example of this would be a sprinkler system valve being closed, this would show up as a supervisory signal on the control unit. Here is a blog discussing some of the places you may find a fire alarm control unit.
The initiation of a fire alarm system includes all the devices and circuits that send a signal to a fire alarm to provide the status of a protected space or the existence of a fire. Initiation devices include, but are not limited to heat detectors, smoke detectors, water flow switches, manually actuated devices, and pressure switches. Depending on the system, the signal from an initiating device can create an alarm condition or a supervisory condition. Based on the type of detectors and fire alarm control unit, the signals can be sent over an initiating device circuit (IDC) for conventional systems, or a signaling line circuit (SLC) for addressable systems. For more information regarding fire alarm initiation, take a look at this blog I created diving deeper into fire alarm initiation.
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