FIRE SECURITY SYSTEM

Most people have experienced a fire alarm system in action, whether it was during school, as part of a planned evacuation drill, or an accidental alarm during an event. But rarely do people think about how a fire alarm system actually works. The basic fire alarm system has four main purposes:

• Detect a fire
• Alert occupants of the fire condition
• Activate safety control functions
• Alert the local fire department

Some of the functions require complex design and engineering to accomplish, but in all cases these serve as one of the four primary functions.

All the functions of a fire alarm system are accomplished by a series of inputs and outputs. The system inputs consist of fire detection devices and system monitoring devices that activate the control panel and the outputs are responsible for occupant notification and control functions associated with life safety.

FIRE DETECTION

Most of us are familiar with smoke and heat detectors because these devices are installed in our homes. Detecting a fire is typically accomplished by installing smoke and/or heat detectors, manual pull stations and automatic sprinkler system water flow switches. Another important detection device is a water flow switch that detects movement of water in the sprinkler piping, typically done by a paddle-type device that is activated by water moving through a pipe when a sprinkler is activated.

OCCUPANT NOTIFICATION

When it comes to warning building occupants of a fire, you need both audible and visible alarms. Audible alarms include horns (the appliance that produces that loud and very annoying sound) or speakers that play a pre-recorded message and/or allow emergency responders to provide spoken instructions to the occupants. Visual notification appliances, or strobes, can provide notification to occupants that are hearing impaired. Each building type will require a different type of occupant notification system.

CONTROL FUCTIONS

There are many different types of control functions that the typical fire alarm system performs. The activation of a duct mounted smoke detector will shut down the heating ventilation and air conditioning (HVAC) equipment to prevent the migration of smoke to non-affected areas of the building. A smoke detector in an elevator lobby will automatically recall the cars to a designated floor.