Fire detection and alarm systems are installed in buildings to comply with one or two of the main objectives, namely the protection of life and the protection of property.
A fire alarm system is a number of devices that all work together to detect and warn people in the event of an emergency. If any of the components detect smoke or heat or if someone operates the break glass unit otherwise known as a manual break point, then the sounders or bells operate. They sound like a siren, with alternating frequencies, and operate to warn others in the building that there may be a fire and to evacuate. Some alarm systems incorporate a signalling system which will automatically alert the fire brigade e.g. hospitals.
What is a Fire Alarm System?
The choice of a fire alarm system will depend on the building purpose, its structure and use and current legislation. In new or altered buildings the enforcement body is the local building control and fire safety building regulations. All existing buildings except domestic premises are subject to The Regulatory Reform (Fire Safety) Order 2005. Under the regulations a responsible person should conduct a fire risk assessment. A fire risk assessment can be requested by the Fire and Rescue service or even the Ministry of Housing, Communities and Local Government. The main standard for fire alarm systems is BS5839.
Alarm systems are divided into three types of systems M, L and P Systems: –
- Category M systems are manual systems which do not have an automatic fire detection.
- Category L systems are automatic systems which are intended to protect life.
- Category P systems are automatic systems which are intended to protect the property.
Fire Alarm System Components
Fire Alarm Control Panel
A fire alarm control panel is the heart of a fire alarm system and has many roles to play. The panel monitors the system for any detector activation, for faults, it activates warning devices when needed and it generally provides power to the devices in the fire alarm system. The panel is also used to control the components and to reset or test the system, some panels have a time-delay to allow to check for a false alarm before the full alarm is activated.
There are two types of control panels addressable and conventional fire alarm panels.
- Addressable control panels are considered the most advanced and each device on the system will have a unique identifying address. The panel will be able to identify which device has triggered the alarm, whether it was a smoke detector, a call point or heat detector.
- Conventional control panels are considered the most basic and therefore more economical detecting devices e.g. smoke detectors are connected on wires forming a loop. If there is an activation of the alarm it is difficult to highlight where the alarm originates from as a single zone can have up to 32 detectors attached to the panel.
Manual Call Points
Manual call points are used to trigger an alarm in the event of a fire. They are operated by a simple button press or when the glass is broken revealing a button to activate the alarm system.
A call point should be installed at a height of 1.4m above floor level at an easily accessible and visible position. Usually, this includes exit routes, staircase landings and at all exits to the outside.
Fire detectors are designed to detect one or more of the characteristics of a fire whether it is from heat or smoke. There are different types of fire detectors i.e. heat, ionisation, photoelectric and ionisation/photoelectric. The difference between these detectors is how they detect fires, heat being from temperature, the other three from smoke. The best detector is the combination ionisation/photoelectric unit. There are various types of detectors: –
- Heat detectors include a sensor that responds to the rate of rise of temperature.
- Smoke detectors use one or both of the two principles of detection ionisation and/or optical
- Optical beam detectors are detectors which comprise of a light source operating at infrared frequencies and a receiver.
- Combustion gas detectors that respond to one or more of the gases produced by a fire.
- Flame detectors detect the infrared and/or ultraviolet radiation that is emitted by the flames.
- Multi-sensor detectors contain more than one sensor, each of which responds to a different characteristic of a fire.
- Video fire detectors are video cameras that monitor the protected area.
A correctly designed and working fire alarm system will give enough warning to save lives, so if you are considering a fire alarm system for your premises ask us for a full site survey which will indicate your needs before you commit to a system that might not be fit for purpose. We also provide periodic fire alarm system maintenance to ensure that your system meets with the current British Standards.
For more information about Fire Alarm Systems and how we can help specify, install or maintain them call us on 0330 6600264 or email [email protected]
Until Next Time… Stay Safe!