Components of a Fire Alarm System?

MeyerFire University | FA001.02

By Tyler Mobley, PE

< PREVIOUS

NEXT >

RESOURCES

FA100 SERIES

RESOURCES

NOTES

• Notes Page [PDF]

FA100 SERIES

1. What is a fire alarm system?
2. Components of a fire alarm system?
3. What questions does an AHJ want concerning fire alarm?
4. What are the different types of fire alarm systems?
5. Different types of Protected Premises Systems?
6. What is a Municipal fire alarm system?
7. What is single- and multi-station fire alarm?
8. Crossword Challenge: Fire Alarm Terminology
9. What are household and combination systems?

---

TRANSCRIPT

What are the components of a fire alarm system?  

Well, a fire alarm system is comprised of a variety of panels, devices and appliances connected together through pathways to create an integrated system.  

These components include initiating devices, notification appliances, and control equipment.  

Beginning with initiating devices, there are two different categories of initiating devices. Devices that initiate alarm signals and devices that initiate supervisory signals.  

Beginning with alarm initiating devices.

We start with manual pull stations.  

Manual pull stations can be either double-action or single-action.  

Double-action require two means of operation to activate an alarm and single-action only require one operation to activate an alarm.  

Smoke detectors.  

Smoke detectors come in a variety of types.  

There's photoelectric spot type smoke detectors, ionization spot type smoke detectors, projected beam smoke detectors, air sampling or air aspirating smoke detectors.  

Each one has a specific application that they're typically used in.  

Your most common smoke detector is your photoelectric spot type smoke detector.  

Areas of large volume  

Projected beam smoke detectors are typically used to project a beam across that space, and when that beam is obstructed it activates an alarm.  

Air sampling or air aspirating smoke detectors are typically used in sensitive spaces. They take air samples from the space through sampling tubes to detect particles of combustion early on, these devices are typically highly sensitive.  

Then we move on to heat detectors, heat detectors or either fixed temperature rate of rise or rate compensated your fixed temperature or heat detectors.  

Activated a set temperature rate of rise and re-compensated heat detectors detect a rapid increase in temperature, then there's flame and spark detectors.  

These detect radiant energy. For instance, a flame detector may be called a VAR. If it detects ultraviolet radiation in infrared radiation.  

And last we have water flow switches. Water flow switches are initiating devices.  

It's part of the fire alarm system that are integrated with the automatic sprinkler system to detect water flow and activate an alarm signal.  

Moving on to supervisory signals, we start with the duct smoke detector.  

Duct smoke detectors are smoke detectors either installed within ductwork or mounted adjacent to the ductwork with sampling tubes into the ductwork to detect smoke moving through ductwork. These can activate an alarm, or a supervisory signal.  

Carbon monoxide detectors, carbon monoxide detectors do exactly what their name says. They detect carbon monoxide. These are typically supervisory, but in some instances they may be required to be alarm signals.  

Now valve supervisory switches, or tamper switches. This is also another initiating device that is integrated with the automatic sprinkler system or a fire suppression system.  

That detects an off-normal position of a valve. For instance, if you have an open normally-open valve that is off normal or closed, it's going to activate a supervisory signal.  

Fire suppression systems such as dry pipe, automatic sprinkler systems and pre-action systems have pressure supervisor switches.  

These switches detect off-normal pressure, for instance low pressure or high pressure, some clean agent, special application fire suppression systems may have an abort switch abort switch when activated prevents the system from discharging and creates a supervisory signal.  

These same type of systems may have a maintenance bypass switch. So when the system is being maintained it prevents the system from discharging and when that says the switch is in the bypass mode, it creates a supervisory signal.  

All right, moving on down to notification appliances, there's two primary categories for your notification appliances.  

We have audible notification appliances and visible notification appliances.  

Audible notification appliances may include bells, chimes, horns, low frequency, Sounders and speakers.  

Bells aren't typically used anymore. Occasionally they will be required on the exterior of buildings for specific applications.  

Chimes are primarily used in private mode applications such as institutional occupancies and horns.  

Your standard notification, audible notification in most commercial buildings that do not have voice evacuation.  

And then low frequency Sounders are what's required in sleeping units. These operate at 520 Hertz and are intended to wake up sleeping occupants and then last speaker.  

Speakers are used to deliver live or prerecorded voice messages.  

Now visible notification appliances. The primary visible notification appliances is strobe.  

Some industrial applications may have a beacon and some mass notification application.  

Actions may have a textual message notification appliances. 

And then there are combinations of audible and visible notification appliances 

Now moving into control equipment, we're going to start with the fire alarm control unit.  

This is the brains of the fire alarm system. If you think of it, it's the computer and everything else is peripheral to the fire alarm control unit, such as a keyboard or a malusis peripheral to a computer. All signals are received or transmitted and transmitted through the Fire Alarm Control Unit.  

There's also the Emergency Communication Control Unit. These control units control voice evacuation systems. The live messages go through this. The prerecorded messages are saved in the system.  

In addition to that, there's voice audio distribution panels. These are integrated or in addition to an emergency communication control unit to help deliver or push the live messages or prerecorded messages throughout the building or campus.  

Then there's notification appliance circuit power supplies. These are in addition to your fire alarm control unit and these power your notification appliance circuits that your horns, chimes or strobes may be connected to.  

And last, there's your communication transmitters. These take your signals that are received through the Fire Alarm Control Unit in a building and transmit them out to the supervisory supervising station.  

Some of these panels include a cellular dialer and IP digital alarm communicator transmitter, a radio transmitter, and depending on the requirements, these may vary in depending on the capabilities within the area.  

These type panels will vary from project to project.  

And last, the pathways that bring all these panels and components together are our circuits. 

To start you have a signaling line circuit. Signaling line circuits are included in an addressable fire alarm system in all initiating and control devices in the field are connected to the signaling line circuit.  

Then there's the initiating device circuit and that's exactly what the name says. All the initiating devices and a conventional system may be connected to initiating device circuit or the circuit from a addressable monitor module to initiating device is an initiating device circuit.  

Then there's the notification appliance circuits. Again, same thing as the name says, it connects all your notification appliances, so your speaker circuits your strobe circuits, your horns circuits and these will be. These are considered your notification appliance circuits.  

Then there's the network circuits. Network circuits connect panels together. Especially if you have an intelligent nodal fire alarm fire alarm system, your fire alarm control units are all connected on a network data circuits data circuits are used such as your RS485 to connect annunciators panels.  

Those are the components of a fire alarm system.  

This is a very high level overview and you'll learn more and more about these components as you move through the modules. 

I am Tyler Mobley, this is MeyerFire University.