How Do Fire Alarms Work – Brief Overview

If you are looking for a fire warning system you may be asking yourself how do fire alarms work? But before we look at that, let’s look a little bit into how they are built and which is the role of each component of a fire alarm system.

A fire alarm includes the following components:

  • The Detection Devices: these are the parts that detect an unusual amount of smoke or an extreme heat in the room.
  • The Audio Devices: this is the device that makes the alarm noise, so people can get notified about the potential presence of fire in the building.
  • The Visual Device: this is either a beacon or a strobe used in areas where the ambient noise level is quite high.
  • The Fire Alarm Control Panel: this is the brain behind the system that monitors all devices to make sure everything is okay and if any detectors are activated will identify the location either by zone or exact location dependent on system type.
  • Additional equipment: such as the call Points for raising the alarm or interface units to turn off gas supply or open roof vents etc.

Smoke Detectors

The smoke detectors can be either optical or with ionization. Optical smoke detectors “see” the smoke through infrared light sensors. Smoke particles entering the sensor, light gets scattered. This is what triggers the alarm. Ionization detectors have a different working principle: smoke particles reduce the air ionization, thus triggering the alarm.

Heat Detectors

Heat detectors monitor the environmental temperature. In case of an extremely abrupt rise, they trigger the alarm. Some heat sensors will have a pre-set for the maximum allowed temperature in the room. Once this threshold is exceeded, it causes the alarm to go off, regardless of any other parameter.

Fire Alarm Control Panel

Now that you know what’s inside, it’s easier to understand how fire alarms work. Each time the smoke or heat sensor detects an abnormally high level of smoke or temperature, it sends signals to the fire alarm control panel making that part of the system start its job and raise the alarm. The sounder alerts humans in the building, so they can call the fire brigade and direct themselves and others towards the emergency fire exit.

If you wanted to know how fire alarms work, now you have the basic knowledge. Nonetheless, you should be aware that there are multiple types of alarm systems, so if you want to install one in your building, you should probably contact a specialist who could give you more details about what’s available. For instance, modern fire alarms may have an automatic dial out function that calls the emergency services in case the alarm goes off out of hours. If you have this function then it is essential that the system is set up correctly and maintained sufficiently as false call-outs to the fire service are expensive and can potentially distract them from a real fire. This is expense is being passed to the business owner in an increasing number of places around the UK from the start of 2014.

Regular Maintenance

All alarm systems should be periodically checked and tested in order to make sure they are functional. Periodical tests are needed because fires are rare, therefore you can never know whether your alarm system is still working or not.

If you want to know more or need to buy an alarm system please contact us at Fire & Electrical Safety Ltd and we will be happy to help. If you want to look in more depth at any particular alarm system please take a look here at our engineer’s corner.