Fire Alarm Systems

Buying a fire alarm system is one of the most important things you can do to keep your home safe. In case a fire occurs, you aware to become aware of it as soon as possible so that you can either put it out or escape.

The first step to protecting lives and property from the consequences of fires is setting up a high-quality fire alarm system. After installing it, you must keep the system well-maintained to make sure it’s always working at its best.

Fire alarm is a unit made of several devices, which use visual and audio signalization to warn people about a possible fire, smoke, or carbon monoxide occurrence in the area of coverage. Fire alarms are usually set in fire alarm systems to provide zonal coverage for residences and commercial buildings. The warning signal is either a loud siren/bell or a flashing light, or it can include both. Some fire alarm systems use additional warnings, such as sending a voice message or making a phone call.

Fire alarms found in Offices, Factories, and public buildings, are a part of our everyday routine. They are often overlooked until there is an emergency at which point, they might just save our lives.

Fire Alarm Componets

Whatever the method of detection is, if the alarm triggers, sounders will operate to warn people in the building that there may be a fire and to evacuate.

Fire alarm system may also incorporate a remote signal system which could then alert the fire brigade via a central station.

The “Brain” of the fire detection system is the Fire Alarm Control Panel. It is the central hub for all of the detector signals wired to and provides a status indication to the users.

The unit can also be set up to simulate an alarm for use in routine Fire and evacuation drills. This helps all staff know what action to take in the event of a real fire.

Fire Alrm Systems in Kenya

How a Fire Hubtech limited Alarm System Works

Contemporary fire alarm systems use automatic functions to detect the occurrence of an event that may result in a fire. They receive a signal from a fire sensor (smoke, heat, or carbon monoxide detector) and automatically transmit it to the fire alarm panel.

In wireless systems, the signal from the detectors to the control panel transmits with radio frequency. Heat detectors usually have built-in thermistors to sense the heat. Carbon monoxide detectors use integrated chemical, electrochemical, Opto-chemical, or biomimetic cells to trace the gas. Smoke detectors use photoelectricity or ionization to detect smoke or combustion particles. Combined detectors use several mechanisms.

The fire alarm panel activates the flashers or the sounders, turns on sprinklers, or makes a call to the authorities or the occupant If the fire alarm system is addressable. The source of the occurrence points on the control panel. Users on separate floors or in connected buildings notified in several ways: by horns, gongs, and loudspeaker messages. This advises appropriate action for each department.

The 3 States of Fire Alarm Systems

As mentioned above, our fire alarm panel monitors and indicates what state the system is in at all times. For most systems, there are three states of operation: Normal, Alarm, and Trouble.

When all devices, appliances, wiring, and circuitry are operating correctly, and alarms inactive, the system is operating in a Normal State.

When an initiating device activates, the system goes into an Alarm State. The indicating appliances will sound, alerting building occupants to the danger. The alphanumeric display on the control panel will indicate from which zone of the building(s) the alarm is originating. This allows the emergency personnel to quickly respond to the correct area.

Should a short or open wiring develop in the circuits connecting the fire alarm panel and initiating devices, or within the panel’s wiring or zone cards, or if the system’s phone line connection is not functioning, then the system goes into Trouble State. This is also displayed on the control panel. The panel will indicate which zone the issue is in, and a buzzer will sound to alert maintenance personnel to the problem. While the buzzer is loud enough, it is not as loud as the indicating appliances.

How Do Hubtech limited Fire Alarm Systems Detect a Fire?

The fire alarm panel connects to the system’s initiating devices through either 2- or 4-wire circuits. This circuitry allows the control panel to monitor the state of its initiating devices, usually by zones, identifying whether the devices are in normal or alarm mode. The control panel shows these readings on its display panel.

When a fire starts, the smoke or heat will activate one of the initiating devices. Someone can also activate the manual pull station, alerting the fire alarm system to the fire and putting it in alarm mode.

What Happens Once our Fire Alarm System Activates?

Once the system goes into alarm mode, two things should happen:

The indicating appliances should sound the alarm, notifying everyone in the building of the danger.

A call should go out via the system’s telephone lines to the monitoring company.

In some fire alarm systems, it may also activate fire suppression systems to help fight the fire until emergency personnel arrives.

How Do You Disarm a Fire Alarm?

It is important for the building manager or maintenance crew to understand the use of the fire alarm panel, especially if it is in troubled fencing with false alarms.

On the touchpad of the control panel, there are alarm and trouble silence options as well as a system reset option. This is used once the source of the alarm or notification gets identified and can be correctly addressed.

Different Types of Fire Alarm Detectors

Fire System Equipment

At the core of a fire alarm system are the detection devices, from sophisticated intelligent smoke detectors to simple manually operated break glass units. There are a wide array of different types, but we can divide them into groups including:

– Heat detectors

– Smoke detectors

– Carbon Monoxide detectors

– Multi-sensor detectors

– Manual Call Points.

1. Heat Detectors

Heat detectors can either work on a fixed temperature basis, where it will trigger an alarm if the temperature exceeds a pre-set value. They can also work on the rate of change in temperature change detectors work in a similar way to an electrical fuse. The detectors contain a eutectic alloy which is heat sensitive. When a certain temperature reaches the alloy turns from a solid to a liquid which in turn triggers the alarm.

2. Smoke Detectors

There are three basic types of smoke detectors including:

– Ionization

– Light Scattering

– Light Obscuring

2.1. Ionization Smoke Detector

An ionization smoke detector contains two chambers. The first is a reference to compensate for changes in ambient temperature, humidity, or pressure.

The second chamber contains a radioactive source, usually an alpha particle, which ionizes the air passing through the chamber where a current flows between two electrodes.

When smoke enters the chamber, the current flow decreases. This drop in current flow initiates an alarm.

2.2. Light Scattering Smoke Detector

The light scattering smoke detector operates on the Tyndall effect; a photocell and light source separate from each other by a darkened chamber such that the light source does not fall on the photocell.

The passage of smoke into the chamber causes the light from the source to scatter and fall on the photocell. The photocell output is being used to initiate an alarm.

2.3. Light Obscuring Smoke Detector

In the Light obscuring smoke detector, smoke interferes with a light beam between a light source and photocell. The photocell measures the amount of light it receives.

The variation in photocell output is being used to initiate an alarm.

This type of fire detection equipment protects large areas with the light source and photocell positioned some distance apart.

3. Carbon Monoxide Detectors

Carbon monoxide detectors known also as CO fire detectors are electronic detectors used to indicate the outbreak of fire by sensing the level of carbon monoxide in the air. This is a poisonous gas produced by combustion.

In this instance, these detectors are not the same as Carbon monoxide detectors used in the home for protecting residents against carbon monoxide produced by incomplete combustion in appliances such as gas fires or boilers.

Carbon Monoxide fire detectors use the same type of sensor as those in the home but are more sensitive and respond more quickly.

The detectors also have an electrochemical cell, which senses carbon monoxide, but not smokes or any other combustion products.

4. Multi-Sensor Detectors

The Multi-sensor detectors combine inputs from both optical and heat sensors and process them using a sophisticated algorithm built into the detector circuitry.

When polled by the control panel the detector returns a value based on the combined responses from both the optical and heat sensors. They are sensitive to a wide range of fires.

5. Manual Call Points

A Manual Call Point or Break Glass Call Point is a device that enables personnel to raise the alarm by breaking the frangible element on the fascia; this then triggers the alarm.

Different Types of Fire Alarm Systems

Fire Alarm Systems consist of four main types;

– Conventional

– Addressable

– Intelligent

– Wireless.

1. Conventional Fire Alarm Systems

Conventional Fire Alarm System

In a Conventional Fire Alarm System, physical cabling interconnects several call points and detectors, the signals from which wire back to the main control unit.

Call points and detectors arranged in “Zones” help to simplify locating the cause of the alarm, this is important for both the fire brigade and general building management.

Each zone indicates at the Fire Alarm Control Panel either with an indicator lamp, a text display, or in some cases both.

It makes sense that the more we can divide a building into zones, the more accurate locating the alarm trigger will be.

The Control Panel is wired to a minimum of two sounder circuits which could contain bells, electronic sounders, or other audible fire alarm devices.

It is these devices that sound the alarm when triggered.

2. Addressable Fire Alarm Systems

The detection principle of an Addressable System is the same as a Conventional System except that each detector has a set Address (usually using a dip-switch) and the Control Panel can then determine exactly which detector or call point has initiated the alarm.

The detection circuit wires as a loop and up to 99 devices connect to each loop.

It is common for the loop to fit with Loop Isolation Modules so that the loop sections ensure that a short circuit or single fault will only cause the loss of a small part of the system; allowing the rest of the system to function normally.

In the previous two systems, the “Conventional Fire Alarm System” and the “Addressable Fire Alarm System” the detectors are not considered “intelligent” as they can only give output signals representing the value of detected phenomena.

It is up to the Control Unit to decide whether there is a fire, fault, pre-alarm, or other.

3. Intelligent Fire Alarm Systems

Intelligent Fire Alarm Systems

However, in our next type of System, which is an Intelligent Fire Alarm system, each detector effectively incorporates its computer which evaluates the environment around it and communicates to the Control Panel whether there is a fire, fault or the detector head needs cleaning.

Essentially Intelligent Systems are far more complex and incorporate far more facilities than Conventional or Addressable Systems. Their primary purpose is to help prevent the occurrence of false alarms.

Intelligent Fire Alarm Systems are available in 2, 4, and 8 loop versions which mean one single panel monitors large premises.

4. Wireless Fire Alarm Systems

The final type of system we will consider is the Wireless Fire Alarm System.

These are an effective alternative to traditional wired fire alarm systems for all applications. They utilize secure, license-free radio communications to interconnect the sensors and devices with the controllers.

It is a simple concept, which provides many unique benefits and is a fully intelligent fire detection system without the need for cabling.