How Do Fire Alarms Work?


Fire alarms are installed and work to save lives. These alarm systems work to detect early signs of fire and alerts occupants, allowing everyone in the building to evacuate the property and contact the emergency services.

There is a wide variety of fire detection systems on the market, each can vary hugely in technology and what locations they are most suitable for. Here we are going to briefly go through how some fire alarm works which may help you understand why some system are more suitable for your property than others.


Optical Smoke detector

These work by pulsing IR (infrared) LED lights into a sensor chamber. 

When a fire starts, it releases smoke into the air and into the detector. The smoke particles will disrupt or scatter these pulsing lights and cause the detector to sound. 

Where to place these detectors:

These are suitable for bedrooms, living rooms, hallways, and offices. These detectors should not be installed in kitchens as any smoke from cooking will cause it to sound. These are also unsuitable for placement in bathrooms


Heat Detectors

A heat alarm is designed to detect heat instead of smoke. When a fire starts the temperature in the room will rise and enter the heat chamber in the detector.

When the temperature in the detector reaches over a certain level the detector will sound.

Where to place these detectors:

These detectors can be installed in kitchens, this prevents false alarms from cooking. These can also be installed in dusty spaces such as workshops as they are less likely to false alarm from the dust and dirt inside. 


Ionisation Smoke Alarms

These alarms work by creating a small current through the device. When a fire occurs, it will cause smoke to rise into the detector. These particles like an optical smoke detector, will disrupt the current in the detector and cause it to sound. 

Where to place these detectors:

Whilst these detectors have been extremely popular technology in the past, they are slightly radioactive and bad for the environment. These detectors are rarely fitted new now. 

These detectors will be suitably installed in similar locations as an optical smoke detector.


Aspirating System

Different to the devices we have mentioned above, aspirating systems are set up as a large network of pipes. These systems operate by constantly drawing air in and sampling air to test for smoke particles. 

Where to place these systems:

Due to their high sensitivity, these systems work well in places with high ceilings such as commercial warehouses. 

Read our case study where we installed one of these systems in National Trust’s Tyntesfield House.


As mentioned above, all these systems work in different environments. Although here we have had a brief discussion about how the systems work and where they work best, it is preferred to speak to an expert when deciding to install a life safety system. 

Here at A.P.E Fire & Security, we have a team of expert surveyors on hand to assist assess the property and discussing what fire safety system would be preferred and needed. From here they will go away and design the system. 

We design, install, and maintain fire alarm systems for a range of building types, uses, and sizes across the UK. We are a BAFE accredited company assuring you of our competence to design, fit and service your fire alarm system to the highest standard in the industry. 

Get in touch today for your FREE, no-obligation survey today!!


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