Fire Suppression design

Designing the fire detection, for a fire suppression system is similar to what would be required for a standard building fire alarm system.
When designing a fire suppression system, the type of detector to use used is as follows:
The selection of detectors of the fire alarm panel should be in accordance with the recommendations given in BS 5839-1 and, where applicable, BS 6266.
In some circumstances, fire detection considerations might dictate the
need for use of two different principles of detection (e.g. optical smoke
detectors and ionization chamber smoke detectors) to ensure the
earliest warning of fire and give the fire suppression system the maximum amount of time to extinguish the fire. In such circumstances, an even distribution of each type of detector should be provided throughout the protected
space. Where coincidence is used, normally it should be possible to
achieve coincidence from two detectors of the same operating
principle. In these cases, if, for example, two independent circuits are
used to achieve coincidence, there should normally be an approximately equal number of detectors of each principle connected to each of the independent circuits. For example, where four detectors are required to protect the space and these comprise two optical smoke detectors and two ionization chamber smoke detectors, there should be one optical smoke detector and one ionization chamber smoke detector on each circuit.
However, it is not always necessary to use two different principles of
fire detection. For example, given the type of fire anticipated and the
speed of detection required, it might be acceptable to use detectors of a single type.
See a video of a Fire suppression system in action.

Fire alarm design - Zones

Fire alarm design should take into account the recommendations applicable to fire detection zones that contain non-addressable automatic fire detectors. The following recommendations are applicable.
a) The floor area of a single fire alarm zone should not exceed 2 000 m2.
b) The search distance (the distance that has to be travelled by anyone responding to a fire alarm signal after entry to the zone in order for the location of the fire to be determined visually,should not
exceed 60 m.
Having entered the zone, the person responding to the alarm signal need not reach the seat of the fire within the recommended search distance; it is only necessary to become aware of the location of the fire.
In measuring search distance, the worst case, in which the fire is located at the furthest concealed area from any likely
point of entry to the zone, should be considered.
Automatic fire detectors within any enclosed stairwell, liftwell or other enclosed flue-like structure should be considered as a separate detection zone. Manual call points located at final exits to open air
from stairwells may be incorporated within these detection zones ,but may alternatively, be incorporated within the detection zone.

Fire Alarm Zones

In many buildings, the evacuation strategy will be very simple; on operation of any fire alarm manual call point, or detection of fire by  automatic fire detection, fire alarm sounders will operate throughout the building to indicate the need for evacuation of the entire building.
In larger, more complex buildings, the fire “Evacuate” signal may, in the first instance, be restricted in extent (e.g. to a single floor, a limited number of floors or a limited area of the building). In other areas, an fire “Alert” signal may be given to warn occupants of the fire alarm signal, without any requirement for those occupants to
evacuate.

In order to support such arrangements, it is necessary for the building to be divided into a number of individual alarm zones and for the installation of an addressable fire alarm system.  The operating state of fire alarm sounders in any alarm zone is independent of the operating state of fire alarm sounders in all other alarm zones. The fire alarm sounders control by the addressable fire alarm are thus grouped, so that, at any point in time, all alarm sounders within any given alarm
zone are in the same state (i.e. silent, giving an “Alert” signal or giving an “Evacuate” signal).
The need for sub-division of a building into discrete alarm zones may arise for a number of reasons,
including:
1.the use of phased evacuation.
2. to avoid unnecessary disruption when false alarms occur.
Any other circumstances in which a two stage alarm arrangement applies.
Since it will be the case that, when occupants of one alarm zone are required to evacuate, occupants of one or more alarm zones above, below or adjacent to that zone will be expected to remain in the building, every alarm zone needs to be separated from all other alarm zones by fire resisting construction. (In some complex
public buildings, such as shopping centres, alarm zones are designed to coincide with smoke control zones,
which are separated from each other by smoke curtains, rather than fire resisting construction. However, in this case, the audible signal is normally given by a voice message, rather than audible fire alarm devices.)
As the sub-division of a building into alarm zones implies that, in the early stages of a fire, occupants in
certain areas will not be expected to evacuate, the configuration of alarm zones might require approval by
the authority responsible for the enforcement of fire safety legislation in the building.

Fire alarm control panel – Fire Systems Ltd

Below is information for convention fire alarm panels used by Fire Systems Ltd.
Detection zone wiring
The detection zones from our convention fire alarm panel, provide a nominal 24V DC to power the conventional fire detection. The fire alarm wiring is monitored for open and short circuit fault conditions by removing the 6K8 end of line monitoring resistors that are supplied fitted to the fire alarm control panels’ terminals and placing them across the last device that is wired to the zone circuit.
Fire detection zone circuits must be wired as a single, radial circuit with no spurs or T junctions to enable the monitoring circuit to work correctly.
On T series fire alarm panels, polarised sounders must also be wired across the detection zone but in reverse polarity to that shown by the zone terminals. At least one sounder should be fitted to each fire detection zone. Each zone can be configured individually as a 2-wire type zone or a non 2-wire type zone using configuration options C1 to C8.
For non 2-wire fire alarm system that are required to comply with BS5839 Part 1: 2002 detector removal requirements, detector bases fitted with a Schottky diode should be used and the end of line resistor replaced with an LCMU active end of line monitoring device.

Radio linked fire alarm systems

Some of the recommendations, applicable to wired fire alarm systems, are unsuitable for, or cannot be applied to, radio fire alarm systems. These include, in particular, those relating to power supplies and fault monitoring.
Additional recommendations apply to radio-linked fire systems in order to address the integrity and performance of the radio communications link between components and the fire alarm control and indicating equipment.
In practice, no fire systems can have total reliability, but one of the objectives of good fire system design is to reduce the probability of the fire alarm system being inoperative in the area of a fire when the fire starts. It is useful that the advantages and disadvantages between the two technologies, hardwired and wireless fire alarms and radio linked systems, are different because this allows for a system to be installed that suits the site. Great care needs to be taken when assessing a site and choosing the technology to use, as neither the wireless fire alarm nor hardwired system is singularly suitable
for every site.
Components of a fire system interconnected by radio-links may include fire alarm devices, such as fire alarm
sounders, as well as detectors and manual call points. However, exercising the fire system with testing and evacuation drills in excess of those recommended by the manufacturer can reduce the life of the radio-linked fire alarm sounder batteries. Automatic silencing of radio-linked sounders on wireless fire alarm systems, is sometimes employed to overcome the potential for undue discharge of sounder batteries. However, sounders with this facility need to reactivate with any new fire or phased evacuation command. Such a facility ought not to impair the system’s ability to provide an adequate audible warning to the occupants of the building in the event of fire.
Other components of a radio fire alarm system may include radio relay units, which are installed remote from
the control and indicating equipment so as to extend the range of the system. Where such relay units are separate control and indicating panels, this is a form of networked system .
Radio communications may also be used to link a small number of detectors and other components to what is essentially a wired system. The recommendations of this standard apply equally to integral radio-linked systems of this nature.

Wireless fire alarm systems

Radio fire alarms, or also refer to as wireless fire alarms are becoming more popular as the technology improves.
A Radio fire alarm/Wireless fire alarm should comply with all recommendations BS EN 54-25.
In accordance with BS5839-1, clause 27 All fire alarm radio-linked components should be supplied from at least two independent power supplies. These can be either:
i) the normal mains supply plus a reserve battery (primary or continuously charged secondary); or
ii) a primary battery plus a second primary battery; or
iii) a primary battery plus a secondary battery.
Components, other than fire alarm control and indicating equipment, may utilize batteries to provide the normal power supply;
Wireless fire alarm/Radio fire alarm, that use power supplies incorporating one or more primary batteries should give 30 days warning of impending battery failure". This should be indicated as a low battery warning condition at the control and indicating equipment;
At the point at which the power supply(ies) to any radio-linked component can maintain the component in normal operation for no more than seven days, and, in addition, in the case of fire alarm
devices, 30 min in the alarm condition, a fault warning should be given at the control and indicating equipment;

Fire alarm spacing and siting of fire detectors

When designing a fire alarm, the heat and smoke detectors installed, depend on convection to transport hot gases and smoke from the fire to the detector.
When designing fire alarms, spacing and siting of these detectors needs to be based on the need to restrict the time taken for this
movement and to ensure that the products of combustion reach the fire detection in adequate concentration. In a building, the hottest gas and the greatest concentration of smoke will generally form at the highest parts of the enclosed areas, and it is here, therefore, that the fire detection need to be sited.
As the smoke and hot gases from a fire rise, they become diluted with clean, cool air, which is drawn into the plume. Hence, the size of fire required in order to operate heat or smoke detectors increases rapidly as the height of the ceiling above the fire increases. To some extent, this effect can be countered by the use of more sensitive detectors.
fire alarm system, incorporating optical beam detectors are less sensitive to the effects of ceiling height than are point-type detectors, since the increased size of plume will involve a greater proportion of the path length of the optical beam and help to alleviate the effects of reduced smoke density. In addition, the entrainment of air cools the gases. If the ceiling is high and the ambient temperature in the
uppermost areas within the protected space is high, the plume of smoke and hot gases may reach ambient temperature before reaching the ceiling. If the temperature of the surrounding air increases with height, (e.g. as a result of solar gain), it is possible for the air at the uppermost levels to be at a higher temperature than that of the plume. The plume will then spread out to form a smoke layer before it reaches the ceiling, as though there were an “invisible ceiling” at a specific height within the protected space. This is known as
stratification, and, at this stage of the fire growth, the smoke and hot gases will not operate ceiling mounted detectors, regardless of their sensitivity.

Fire alarm manual call points

Fire alarm manual call points need to be prominently sited, readily distinguishable from non-fire alarm call points and need to be distributed such that, from any point in the building, it is impossible to leave the storey or the building without passing a fire alarm manual call point.
When designing a fire alarm system, sufficient call points need to be provided to minimize, to a reasonable extent, the delay between discovery of a fire and the sounding of the fire alarm system. Where the fire hazard level is high and rapid fire development is
anticipated, this delay needs to be commensurately shorter.
Manual call points can, if present in unsupervised areas, be subject to malicious operation. For this reason,they are not normally provided in, for example, public common areas of shopping complexes and certain
public houses. In public car parks within a building, use of an emergency voice communication system could be considered instead of manual call points.

Fire alarm installation practices and workmanship

The nature and quality of the fire alarm installation work needs to be such as to maintain the integrity of the fire alarm system and minimize the duration and extent of disablement of the system during maintenance or modifications. Installation practices and workmanship need to conform to the requirements of BS 7671.
Penetration of construction (e.g. for the passage of cables, conduit, trunking or tray) need to be “fire stopped” to avoid the free passage of fire or smoke, regardless of whether the construction has a recognized degree of fire resistance.
Recommendations:
The following recommendations are applicable.
1) The entire electrical fire alarm system installation should conform to the requirements of BS 7671. In general, the recommendations of this standard supplement, but do not conflict with, these requirements. Where any such conflict is considered to exist, the recommendations of this standard should take precedence.
2) Cables which are directly fixed to surfaces should be neatly run and securely fixed at suitable intervals, in accordance with the recommendations of the cable manufacturer. Cables should not rely on suspended ceilings for their support.
3) The installer should ensure that all wiring complies with, at least, 26.2f) to 26.2o).
d) Joints in fire alarm cables, other than those contained within the enclosures of equipment, should be avoided
wherever practicable [see 26.2g)].
4) So far as is reasonably practicable, cable routes should be selected to follow the recommendations .
Care should be taken to ensure the electrical continuity of electromagnetic screens, including metallic
sheaths of cables.
5) Where new conduit, trunking or tray is installed, its capacity should be in accordance with the
recommendations given in BS 7671.
6) Where a cable passes through an external wall, it should be contained in a smooth-bore sleeve of metal
or other non-hygroscopic material sealed into the wall. This sleeve should slope downwards towards the outside and should be plugged with a suitable non-hardening waterproof compound to prevent the entry of rain, dust or vermin.
7) Where a fire alarm cable passes through an internal wall, a small clearance hole should be provided. If additional mechanical protection is necessary, a smooth-bore sleeve should be sealed into the wall.
8) Care should be taken to ensure that the ends of any sleeves are free from sharp edges which might
damage cables during installation.
9) When a cable passes through a floor, the considerations a
sleeve should extend as far above floor level as is required for protection of the cable it is to carry, but never less than 300 mm.
10) Where cables, conduits, trunking or tray pass through floors, walls, partitions or ceilings, the surrounding hole should be as small as reasonably practicable and made good with fire stopping
materials that ensure that the fire resistance of the construction is not materially reduced. Spaces through which fire or smoke could spread should not be left around the cable, conduit, trunking or tray.
11) If cables or conduits are installed in channels, ducts, trunking or shafts that pass through floors, walls, partitions or ceilings, barriers with the appropriate level of fire resistance should be provided
within the channels, etc. to prevent the spread of fire unless, in the case of ducts and shafts, the construction of the duct or shaft affords equivalent fire resistance to the structure penetrated; in the
latter case fire stopping need only be provided where cables pass into, or out of, the duct or shaft.

Grade of fire alarm system

Fire alarm System Grades relates to the engineering aspects of the fire detection and fire alarm system. Higher Grades of fire system design, tend to provide a greater level of control and monitoring of the system, or greater reliability and availability to perform correctly in the event of fire. The Grade of fire alarm system that needs to be installed depends on the nature of the property, the level of fire risk and the characteristics of the occupants.
Grade F -  fire alarm systems, comprising one or more battery-operated smoke alarms, are the least reliable in the long
term because of the need for battery replacement. For new dwellings, a Grade D system (in which the normal power supply for each smoke alarm is derived from the mains electricity supply and a standby supply is provided) or higher is justified.
However, because of their low cost and ease of installation, Grade F systems (comprising battery-powered
smoke alarms) may be considered for installation in existing dwellings. Their reliability can be improved by use of batteries that have a long anticipated life and that cannot be removed without the use of a tool.
Nevertheless, Grade F fire detection systems are not appropriate in dwellings in which the fire risk to occupants is high
nor where there cannot be a reasonable certainty that, when the dwelling is occupied, batteries will be replaced within a short time (typically no more than five days) of a battery fault warning indication.
Otherwise, a system in which the normal supply is derived from the mains needs to be used (e.g. a Grade D
system).
If, in an existing dwelling, a Grade F fire alarm system would be acceptable, it is acceptable to install a Grade E system
(comprising mains powered smoke alarms). However, if there are likely to be periodic interruptions to the
mains supply, whether due to the inability of the occupier to pay for supplies or due to unreliability of the
mains electricity supply, a Grade D system or higher (in which there is a standby supply) is then necessary.

Where there is a need for readily accessible control of the fire detection and fire alarm system, a Grade C
system or higher might be provided. Where the fire risk calls for a high standard of system monitoring and
availability, it might be appropriate to install a Grade B system. If the dwelling is very large, or is subdivided into a significant number of dwelling units, a Grade A system is likely to be appropriate.
If the purpose of the system is property protection, fire insurers might require a Grade A system. However, for smaller properties, a Grade B or Grade C system might be sufficient.

Recommendations to consider when designing a residential fire alarm system.

The following items below are applicable when designing a fire alarm system in accordance with BS5839-6.
Any requirements imposed by enforcing fire authorities, and any requirements imposed by property insurers, for a fire detection and fire alarm system for a dwelling should clearly state the Category of system required.
If any party, (for example a fire alarm company),is instructed to design a fire detection and fire alarm system for a dwelling (e.g. by means
of a purchase or tender specification), the instruction should include a clear reference to the Category of system required.

Should a fire alarm or a fire detection system be intended to protect both life and property, and specific recommendations for the two Categories of system differ, then the system should comply with the
recommendations for each of the Categories.

Fire alarm design – Category PD

When design a fire alarm to a category PD, the following should be considered.

A fire can start virtually anywhere in a dwelling, although the probability of fire varies significantly from
one room to another. The probability of a fire occurring is usually ascertained by carrying out an on site fire risk assessment, as required by the FSO.

If a fire alarm system is not fitted and the fire is not detected at an early stage, it can grow until it becomes difficult or impossible to extinguish. The highest level of property protection will therefore be given by a Category PD1 system (giving full coverage of all parts of the dwelling). In a large house of high value, or with contents of high value, such a fire system is generally the only Category acceptable to fire insurers. The fire alarm system will normally have a facility for automatic transmission of fire alarm signals to an alarm receiving
centre.
A lower level of fire protection, still giving a useful reduction in fire risk, can sometimes be obtained by the fire alarm installation of fire detectors only in those parts of the building in which there is significant potential for ignition. A Category PD2 system provides partial cover of this nature.

Fire alarm design category LD3 residential

A Category LD3 fire alarm system is intended only to protect circulation areas that would be used as escape routes, by
giving a warning if smoke is detected in these areas, so that occupants can escape before heat or smoke make
this impossible. Therefore, the fire detection is positioned on the escape routes.

A Category LD3 fire alarm system cannot be expected, with any degree of reliability, to protect people who might be involved with the fire at ignition or in its early stages. This Category of fire system might not therefore prevent the death or serious injury of occupants in the room where the fire originates; it is intended only to ensure escape for those not immediately involved. If no fire detector is installed in the room in which fire starts, the time available for evacuation of other areas once fire is detected in the circulation area might be
quite short.

In a large family house adapted to provide accommodation for several households in separate self-contained units (a house in multiple occupation), a fire in one dwelling unit can be a hazard to occupants of other units.
In this case, the fire detection and fire alarm system normally needs to extend across the boundaries between occupancies or be interconnected with systems in other occupancies. In practice, it is often appropriate for there to be a single integrated fire detection and fire alarm system that will alert all occupants before a fire
in any dwelling threatens the communal escape routes, and that will provide early warning of any fire that starts in these escape routes. This objective is additional to that of enabling occupants of the dwelling in which fire starts to escape before their escape routes become impassable owing to heat or smoke.

In the case of purpose-built flats or sheltered housing, the degree of compartmentation between occupancies is normally sufficient to ensure that fire is contained in the dwelling of origin for a prolonged period. During this time, other occupants can remain in reasonable safety within their own dwellings. Accordingly, this part
of BS 5839 does not provide recommendations for fire detection and fire alarm systems that incorporate detectors in the communal areas or ancillary accommodation (e.g. plant rooms) within purpose-built flats
or sheltered housing. If, however, the provision of detection in these areas is considered desirable, it is essential to refer to the guidance contained in BS 5588-1, and it is appropriate that such fire detection and fire alarm systems comply with the recommendations of BS 5839-1.

Hotel fined after fire alarm system failed

I was reading a article on the “In4fire.com” website.

The article read as follows: Apparently, Magistrates have ordered a hotel manager to pay fines and costs totalling £5,355 after a fire detection and fire alarm system failed to activate in a fire situation.

Nine residents were staying at the Plume of Feathers at Harley, near Shrewsbury, in the early hours of July 27 last year when the wife of the hotel manager opened the bedroom door to find smoke in the corridor, according to Shropshire Fire and Rescue.

She tried to raise the alarm by activating manual call points but the fire alarm failed to activate. Her husband and other members of staff had to knock on bedroom doors to wake guests.

Area manager John Das-Gupta said that although the premises were fitted with a full automatic fire detection and fire alarm system, no fire alarm maintenance was in place, and it had not been adequately tested by the manager. Because of this, the fire alarm failed to operate and raise the sleeping occupants.

Michael Martin pleaded guilty to one offence under the Regulatory Reform (Fire Safety) Order 2005 at Shrewsbury Magistrates Court on 17 September.

The story above highlights the importance of having the fire alarm and any other fire protection equipment service and maintained in accordance with the relative standards.

Fire Systems Ltd, provide fire alarm maintenance and many other maintenance services. For more information contact Fire Systems Ltd, on www.firesystems.co.uk

Fire alarm systems for the protection for life – Category LD2

All HMO’s need to be provided with an appropriate fire detection and fire alarm system. The system installed can be a wireless fire alarm or a wired type system. The greatest benefit to life safety in a residential fire alarm is given by a full-coverage system (Category LD1). Such a fire system will give the earliest practicable warning of fire to occupants, wherever ignition occurs.

However, a good level of fire protection can normally be obtained from a Category LD2 designed fire alarm system, in which detection
is only provided at points where the fire risk is high or where combustion products would present a significant hazard to life. A Category LD2 designed fire alarm system might, for instance, have detectors only in the circulation areas of the dwelling, the living room and the kitchen; other areas might be left without detector coverage.
The areas protected by a Category LD2 system include escape routes, i.e. those areas that would be protected
by a Category LD3 system.

Wireless fire alarm are a popular choice in today’s residential market, due to the obvious ease of installation and little or no damage to the decoration. Fire Systems Ltd, are a industry known specialist for the installation of wireless fire alarm systems.

Fire alarm categories Part 6

Fire detection and fire alarm systems are usually installed in dwellings to protect life. However, the level of protection afforded to occupants needs to be related to the fire risk. The level of risk is usually established by carrying out a fire risk assessment.

The appropriate level can therefore vary considerably. For the purposes of BS5839-6, fire alarm systems are classified as follows, according to the level of protection that they afford.
Category LD: a fire detection and fire alarm system intended for the protection of life.
The designation “LD” is used to distinguish these systems, which are intended only for dwellings, from Category L fire systems
as defined in BS 5839-1, which are intended for the protection of life in any type of building.
Category LD systems are subdivided into:
Category PD: a fire detection and fire alarm system intended for the protection of property.
The designation “PD ” is used to distinguish these systems, which are intended only for dwellings, from Category P systems
as defined in BS 5839-1, which are intended for the protection of property in any type of building.
Category PD systems are subdivided into:

A fire alarm system is rarely installed solely for the protection of property. Accordingly, Category PD systems will normally be designed to comply with the recommendations of this part of BS 5839 for a Category LD system,
thereby constituting a combined Category LD and Category PD system.
Because of the wide range of systems covered by the recommendations of this part of BS 5839, the
specification of requirements for a system by a purchaser, user, enforcing authority or insurer, or the description of a system by a designer or installer, by reference to this standard, without a reference to system Category, will have little meaning.

Fire alarm grades residential

The following recommendations are applicable.
1) Any requirements imposed by fire authorities, and any requirements imposed by property insurers, for a fire detection, wireless fire alarm or a standard wired fire alarm system for a dwelling should clearly state the Grade of system required.

2) If any party is instructed to design a fire detection,wireless fire alarm or standard wired fire alarm system for a dwelling (e.g. by means
of a purchase or tender specification), the instruction should include a clear reference to the Grade of fire system required.

3) The relevant system certificate should clearly state the Grade of fire system that has been designed or installed.

In the case of a Grade A fire alarm system, there will be a separate design certificate, which will indicate the Grade of fire system that has
been designed . In other Grades of system, a single certificate will normally be issued, indicating the Grade of system
that has been designed, installed and commissioned.

Small fire alarm companies are struggling to survive in UK

As many as 45 small fire alarm companies within the fire protection industry are in financial difficulty as the lingering effects of the credit crunch continue to squeeze at the lower end of the market, according to a market analysts. The report states that smaller fire alarm companies have not had the same facilities to ride out the recession as well as their larger counterparts.

“While the larger fire alarm companies have relied on their size, brands and better access to cash, smaller companies have been left high and dry.”

“We have given 45 small companies a ‘Danger’ rating. While conditions have improved of late, I fear a high proportion will fail. Whereas large companies can call on banks and parent companies or cut out loss making parts of their operations, smaller companies are increasingly running out of cash.”

Another point is how small companies are struggling to maintain their market share and being squeezed out of the market. “209 small companies are selling less fire alarm and fire protection equipment  than last year. Clearly they have seen demand for their products dip or worse still, a new fire alarm company, has emerged. With their finances already stretched, they have little left in their arsenal to fight back.”

So what next for these small companies?  “There are clearly too many small fire alarm companies chasing too little market. The inevitable consequence is another round of consolidation with large competitors buying small companies at a discount. Of the 489 companies with assets of less than £3 million, we have identified 186 companies as being vulnerable to takeover.”

Fire alarm design residential

When designing fire alarm systems for residential properties, the following should be considered.

In the case of fire detection grades, Grade D, Grade E and Grade F systems, where more than one smoke alarm is installed the
smoke alarms normally need to be interlinked. Any heat alarms also need to be interlinked with the smoke alarms.
Guidance documents supporting legislation, and written requirements produced by enforcing authorities, often specify only a minimum level of fire system engineering, rather than a particular form of system. These Grades are defined in such a way that a requirement for one Grade of fire alarm system can be satisfied (normally at
higher cost) by the installation of a higher Grade of system; for example, if the fire risk justified the installation of a Grade D system, it would be acceptable to install a fire alarm system of an Grade A, Grade B or Grade C category.
Because of the wide range of fire systems covered by the recommendations of this part of BS 5839, the specification of requirements for a system by a purchaser, user, enforcing authority or insurer, or the description of a system by a designer or installer, by reference to this standard, without a reference to system
Grade, will have little meaning.
Annex B provides further information on each Grade of system, including the advantages and disadvantages of each Grade.

Fire alarm Grades in BS5839-6

The Fire alarm Grades are defined as follows.
Grade A: A fire detection and fire alarm system, which incorporates a fire alarm control panel and indicating equipment conforming to BS EN 54-2, and power supply equipment conforming to BS EN 54-4, and which is designed and installed in accordance with all the
recommendations of sections 1 to 4 inclusive of BS 5839-1:2002, except those in the following clauses, for which the corresponding clauses of this part of BS 5839 should be substituted.

Grade B: A fire detection and fire alarm system comprising fire detectors (other than smoke alarms and heat alarms), fire alarm sounders, and control and indicating equipment that either
conforms to BS EN 54-2 (and power supply complying with BS EN 54-4) or to Annex C of this part of BS 5839.

Grade C: A system of fire detectors and alarm sounders (which may be combined in the form of smoke alarms) connected to a common power supply, comprising the normal mains and a standby supply, with central control equipment.

Grade D: A system providing fire detection in the form of one or more mains-powered smoke alarms, each with an integral standby supply. (The system may, in addition, incorporate one or more mains-powered heat alarms, each with an integral standby supply.)

Grade E: A system of one or more mains-powered smoke alarms with no standby supply. (The system may, in addition, incorporate one or more heat alarms, with or without standby supplies.)

Grade F: A system of one or more battery-powered smoke alarms. (The system may, in addition, also incorporate one or more battery-powered heat alarms.)