Fire Alarm Design
Fire Alarm design – which design category, is right for my property?
When deciding on a new fire alarm system or upgrading an existing system, an important aspect that will be discussed is how many smoke detectors, manual call points and sounders do I need in my building?
This question is usually decided by a fire risk assessment. The assessment will consider the fire risk associated with the property and suggest a fire alarm design category as stated within BS5839-1:2002
Within the standards there are six categories for protecting life:
- M: Manual call points at all exists to the outside and a change of floor level.
- L4 – Protection of escape routes (Category L4: systems installed within those parts of the escape routes comprising circulation areas and circulation spaces, such as corridors and stairways.) The objective of a Category L4 system is to enhance the safety of occupants by providing warning of smoke within escape routes;
- L3 – Protection of the escape routes, plus rooms off of the escape routes. Detectors are installed as per an L4, on all escape routes, plus rooms coming off of the escape routes. Systems designed to an L3 give a warning of fire at an early enough stage to enable all occupants, other than possibly those in the room of fire origin, to escape safely, before the escape routes are impassable owing to the presence of fire, smoke or toxic gases.
- L2 – Is the same as L3, put additional detection is added to areas deemed of a high risk, such as electrical intake areas, kitchens, Boiler rooms etc.
- L1 - Highest level of protection all rooms (The highest possible enhancement of life safety is provided by a Category L1 system. In a Category L1 system, all areas and rooms of the building are protected by automatic fire detectors.)
Fire Alarm Sounders and Bells
The quantities of how many fire alarm sounders or bells that may be required is decided on how many are needed to achieve the minimum sound levels as required by the fire code. The fire code BS5839-1, states a minimum of 65 decibels in open areas, there are some conditions whereby this level can be reduced to 60db, but it is best to aim for 65db as a minimum. Where the back ground noise is above 60db, the fire alarm sounder is to achieve a sound level 5db above the ambient noise level.
Sleeping areas are to achieve not less than 75db at the bed head.
However when speaking about a minimum level, there is a maximum level of 120db.
Choosing a competent Fire Alarm company to design your system.
It is important to ensure whoever is designing your fire alarm system has the necessary experience and qualifications to design a system in accordance with the categories as define in fire code BS5839-1.
A BAFE accredited company such as Fire Systems Ltd, has the required certification to design, install and commission fire alarm systems. We have been designing and installing fire alarms since 1992. If you require advice on a fire alarm, why not contact our office on 020 8541 5646 or complete the contact form.
