Fire Detection Systems
Fire Detection Systems are essential to your building to protect life and property, and all alarms should comply with the recommendations set out in British Standard BS5839-1 2017. The Standards recommend various system categories set out the spread of automatic detection, which impacts the speed at which a fire is likely to be detected, along with recommendations regarding suitable alarm and warning devices such as audio and visual alarms to trigger all out or phased evacuation strategies.
Categories of Fire Alarm Systems
Fire Detection Systems fall under three categories: M, L , and P. Each has a different purpose and requires various levels of interaction to work.
Category L
Category L systems are automatic fire detection and alarm systems with the aim of protecting life. There are 5 levels within this category, each offering a different level of fire protection.
Category L1 Fire Alarm Systems
Category L1 fire alarm systems offer the highest level of life protection. They recommend the installation of both manual call points (MCPs) and automatic fire detection (AFD) throughout the entire premises, including roof spaces and voids. The objective is to provide the earliest possible warning in the event of a fire. Certain low-fire-risk areas, such as stairways, lobbies, and small cupboards, may be exempt from protection.
Category L1 systems are typically found in residential care premises and large office blocks.
Category L2 Fire Alarm Systems
Category L2 fire alarm systems enhance the level of protection provided by Category L3 systems. They include additional detection in areas with a high risk of ignition, identified through a fire risk assessment. Automatic detectors are installed in escape routes, rooms adjoining escape routes, and high-hazard rooms like kitchens, boiler rooms, and plant rooms.
The system aims to provide occupants with sufficient time to evacuate before escape routes become impassable due to smoke and flames.
Category L2 systems are suitable for medium-sized premises accommodating up to ten residents.
Category L3 Fire Alarm Systems
Category L3 fire alarm systems incorporate manual call points (MCPs) at defined positions and automatic fire detection (AFD) in all escape routes, rooms, corridors, and compartments that open onto escape routes. The objective is to provide early warning to occupants beyond the room in which the fire originates, allowing them to utilise escape routes before they become filled with smoke.
Category L3 systems offer broader coverage compared to Category L4.
Category L4 Fire Alarm Systems
Category L4 fire alarm systems feature manual call points (MCPs) placed throughout the building, along with automatic fire detection (AFD) along escape routes, including stairwells. The purpose is to alert people to the danger before corridors become smoke-filled, enabling safe evacuation.
While Category L4 provides detection within escape routes, Category L3 covers not only these areas but also all rooms leading to the escape route.
It is important to note that a Category L4 system does not meet the legislative requirements for buildings accommodating sleeping individuals.
Category L5 Fire Alarm Systems
Category L5 systems are designed to meet specialised fire safety objectives, deviating from the standard recommendations where strict adherence may not be feasible. These systems could include automatically closing metal shutters on shopfronts to contain the fire or computer rooms equipped with an extinguishing system triggered by automatic detection.
The decision to implement a Category L5 system is typically based on recommendations from a fire risk assessment (FRA) and is tailored to address specific risks and client requirements.
Category M
Category M fire alarm systems are primarily focused on places of employment without sleeping risks. These systems rely on manual call points (MCPs) installed on all exits and corridors where individuals are not expected to walk more than 30/45 meters to operate them.
There is no automatic detection in Category M systems, as they depend on the occupants to discover the fire and activate the system. Category M systems are commonly found in workshops or factories.
Category P1 Fire Alarm Systems
Category P1 fire alarm systems focus on protecting the entire building and providing the earliest possible fire warning. Detectors and alarms should be strategically placed in all areas of the building to promptly alert the fire and rescue service upon the outbreak of a fire, thereby minimising property damage.
Conducting a fire risk assessment is crucial in designing Category P1 systems, as it helps identify specific risks present in each room and determines the appropriate detectors.
Category P
These types of systems are purely for the protection of property and fall into two classifications, Category P1 and Category P2.
Category P1 is designed to protect the whole building, Category P2 is installed in defined parts of the building only, which may have a high risk or hazard.
Category P2 Fire Alarm Systems
Category P2 fire alarm systems provide fire detection in specific parts of the building where focused coverage may be required. These areas typically entail a higher risk or hazard, or there is a need to minimise business disruption and protect valuable content.
Audio Visual Fire Alarm Systems
Fire Detection Systems have two methods of alerting their occupants of a fire; these are audio and visual.
Audible Alarm Systems - Audible Fire Detection Systems are the most common type of alarm. Sounds pressure levels will range up to 120dB, depending on the activities occurring within the building and the size of the rooms. In a normal office environment, a lower level of alarm can be installed – whereas a busy factory must have a higher volume. If your premise includes sleeping accommodation, extra sounders must be fitted here to minimise sleeping risks.
Visual Fire Detection Systems - Visual Fire Detection Systems are most used to alert those with impaired hearing or in areas of high volume where occupants may be wearing protective earwear. These can be used instead of, or in combination with audible alarms to ensure maximum effect. Visual alarms most commonly display red lights that are placed high to attract attention but do not impair sight.
The government recommends that both visual as stand-alone alarms and when used with audible Fire Detection Systems should comply with 54 standards.
Smoke detectors utilise one or both of the following principles:
Ionisation Chamber
Ionisation alarms are extremely effective at detecting fast-burning fires. They detect smoke by the reduction it causes in current flows across the electrodes in the ionisation chamber. These types of detectors are typically used in intrinsically-safe or hazardous environments.
Optical Detection
Optical smoke detectors detect smoke by means of the light scatter emitted from the device. These types of alarms are the mainstay of the vast majority of detection systems and are an efficient and cost effective system. Optical smoke detectors can be supplied as a point detection device and a beam detection device which uses a light source with reflector plate to protect larger areas.
How can our team with your fire alarm system planning?
Our Fire System Designers will attend your site to survey the building and discuss your objectives regarding the output of your fire system. Choosing the right detector for the right environment is critical – whether it be heat detectors in places where the air is heavy with steam or dust, or beam detectors when large spaces need to be continual monitored. Our team aims to provide fully specified quotations based on the design elements identified and will also provide feedback on the system’s design, highlighting issues to adapt and maximise the protection of your system.
All the technology that we recommend is compliant with the EN-54 standard which governs the quality of devices and alarms, and our team is constantly on the lookout for new and cutting-edge technology to provide our customers with the earliest possible detection in the event of a fire.
Contact Us
We’d love to hear from you, so drop us a message via the form below or give us a call today!
info@attentivefire.co.uk
02089310468
Unit 4,
297-303 Edgware Road,
NW9 6NB