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برق. قدرت. کنترل. الکترونیک. مخابرات. تاسیسات. - The Guide To Fire Alarm Systems Design BS5839 PART 1: 2002

برق. قدرت. کنترل. الکترونیک. مخابرات. تاسیسات.

دایره المعارف تاسیسات برق (اطلاعات عمومی برق)

The Guide To Fire Alarm Systems Design BS5839 PART 1: 2002

The Regulatory Reform (Fire Safety) Order (RRO) became law on 1st October 2006. Legally you must comply!

What is RRO?
Fire authorities no longer issue fire certificates and those previously in force will no longer have legal status. The Regulatory Reform (Fire Safety) Order (RRO) replaces most fire safety legislation with one new order. It means that any person who has some level of control in premises must take steps to reduce risk from fire, consider how to contain a fire should one break out and then also make sure people can safely escape if there is a fire.

• All fire alarm designs should be based on a fire risk assesment
• All fire risk assesments should be carried out by a competent person
• Fire risk assesments must be reviewed annually

What constitutes a fire risk assesment?
• Identifying fire hazards such as sources of ignition, fuel or oxygen
• Identifying all people at risk in and around the premises
• Evaluating the risk of a fire starting or the risk to people from a fire
• Removing or reducing fire hazards or risks to people from a fire
• Protecting people by providing fire precautions
• Recording any major findings
• Preparing an emergency plan
• Informing and instructing any relevant people
• Providing training for staff and guests
• Reviewing the fire risk assesment regularly and make changes where necessary
• Keeping accurate fire

Where does the order apply?
Virtually all premises and nearly every type of building, structure and open space. If you would like to find out more about the services that Eurotech can provide, please contact us on: T +44 (0) 203 141 0999

This guide is intended to be an aid to designers and installers of fire detection systems. It is not to be used as a substitute for BS5839 which should be read in full. In order to help identify the relevant sections each diagram includes a reference to BS5839 Part 1.



 



 

Fire alarm and detection systems are categorised in the following way:

Property protection fire systems

  • P1 AFD installed throughout all areas
  • P2 AFD installed only in defined areas
  • Life protection fire systems
  • L AFD designed to primarily protect human life
  • L1 AFD installed throughout all areas
  • L2 AFD installed only in defined areas in addition to L3
  • L3 AFD installed in escape routes and rooms opening onto these routes
  • L4 AFD installed in escape routes comprising circulation areas and spaces such as corridors and stairways
  • L5 A non-perspective system in which protected area(s) and/or the location of detectors is designed to satisfy a specific fire risk objective (other than
  • that of L1 to L4)
  • M System design to be operated manually (no AFD)
AFD Automatic Fire Detection

BS5839 Section 5








BS5839 Section 13.2.3


 
A person searching a zone for a fire in a non-addressable fire system should not have to travel for more than 60m to identify the source of a fire


BS5839






Section 22.3


 
A person searching a zone for a fire in a non-addressable fire system should not have to travel for more than 60m to identify the source of a fire

BS5839




BS5839 Section 22.3







 
The sensing element of a heat detection thermistor device should not be less than 25mm below ceiling, and not greater than 150mm below ceiling

BS5839 Section 22.3

BS5839 Section 22.3.







 
The minimum static response to heat devices should not be less than 29°C above the average ambient temperature, or less than 4°C above the highest temperature the device can expect to experience

BS5839 Section 35.2.3

BS5839 Section 22.3.







 
When mounted on a ceiling, smoke detection devices have an individual coverage of 7.5m radius. However these radii must overlap to ensure that there are no 'blind spots'. therefore individual coverage can be represented by a square measuring 10.6x10.6m giving an actual area coverage of 112m2 per device

BS5839 Section 22.3

BS5839 Section 35.2.3.







 
When mounted on a ceiling, smoke detection devices have an individual coverage of 5.3m radius. However these radii must overlap to ensure that there are no 'blind spots'. therefore individual coverage can be represented by a square measuring 7.5x7.5m giving an actual area coverage of 56.3m2 per device

BS5839 Section 22.3

.







 
For ceilings that feature an apex: as long as the height of the apex from the rest of the ceiling is less than 150mm for heat detectors or less than 600mm for smoke detectors, then these can be treated the same as flat ceilings. For higher apexes, a device should be installed to the highest point. The distance to adjacent devices can be increased by 1% per degree of angle of roof up to a maximum of 25%

BS5839 Section 22.3

.






 



 
 









 
Do not put detectors less than 1m from air inlets or air
circulating units

BS5839 Section 22.3

.







 
Devices should not be mounted within 500mm of any obstruction. If the top of a solid partition is less than 300mm from the ceiling then treat it as a wall. Similarly, ceiling obstructions such as beams should be treated as walls if deeper than 10% of the ceiling height

BS5839 Section 22.3

.







 

In corridors less than 2m wide the horizontal spacing of detectors may be increased, the areas of coverage need not overlap as in the case of a room. Any corridor over 2m wide is deemed a room and device spacing should follow the standard for rooms (see page 6).

Please note, heat detectors are not recommended for use in corridors that are escape routes

BS5839 Section 22.3

.








 
Never mount devices closer than twice the depth of light fittings or other obstructions on the ceiling

BS5839 Section 22.3

.







 
Voids less than 800mm in height need to have independent coverage, unless fire or smoke is able to spread from one area to another through the void or risk assessment shows AFD (Automatic Fire Detection) to be necessary

BS5839 Section 22.2

.







 
Vertical shafts like lifts and stairways should have a device mounted within 1.5m of any opening

BS5839 Section 22.2

.







 
Enclosed stairways should have a detector at the top of the stairway and on each main landing

BS5839 Section 22.2

.







 
A person should not have to travel more than 45m along an escape route to reach a manual call point (25m if disabled person to operate, or rapid fire development is likely). Manual call points should be sited at all stairwells and exits from the building

BS5839 Section 20.2

.







 
The centre of the frangible element of the manual call point should be positioned 1.4m (+/-200mm) from floor level (unless a wheelchair user is likely to be the first person to raise the alarm

BS5839 Section 20.2

).







 
The minimum sound level should be 65dB(A) or 5dB(A) above a background noise which is louder than 60dB(A) (if lasting more than 30 seconds) and at a frequency of between 500Hz and 1000 Hz. The maximum sound level should not be greater than 120dB(A) at any normal accessible point. May be reduced to 60dB(A) in stairways, enclosures up to 60m2 and specific points of limited extent

BS5839 Section 16.2.1

.







 
Sounder device cabling should be arranged so that in the event of a fault at least one sounder will remain operational during a fire condition

BS5839 Section 16.2.1

.







 
For areas where people are sleeping, sounder devices should produce a minimum 75dB(A) at the bed-head with all doors shut. in buildings providing sleeping accommodation for a significant number of people, all bedrooms should have both audible and visual alarms

BS5839 Section 16.2.1

.







 
Decibel loss occurs through doors: approximately - 20dB(A) through a normal door and approximately -30dB(A) through a fire door. Unless a sounder is installed in a bedroom, it is unlikely that 75dB(A) will be achieved

BS5839 Section 16.2.1

.









 
Visual alarms such as beacons should always be mounted at a minimum height of 2.1m from floor level

BS5839 Section 17

.







 
Unless MICC cable is used, all cabling should be mechanically protected from floor level up to a height of 2m

BS5839 Section 26.2

.







 
Fire resistant cabling is now required within the whole fire alarm system including the mains supply cables. The use of non-fire resisting cables whether mechanically protected by fire resisting construction or not, will no longer comply with BS5839 Part 1

BS5839 Section 26

.







 
Short circuit isolators limit the effect of one fault to a maximum of 2000m2. '2 simultaneous faults on a circuit should not disable protection within an area greater than 10,000m2

BS5839 Section 12.2.2

.





 


 
The EURB-4 standard conventional base from Eurotech should be wired as above

.





 


 
The EURB=4-EV standard intelligent base from Eurotech should be wired as above


.





 


 
A battery powered, intelligent programming tool is available. The Eurotech EV-AD2 hand held programmer is light, robust and easy to operate and is used for address programming and functional testing


.





 




Risk Assessment

The 'Fire precautions (Workplace) Regulations' require any business employing five or more persons to hold a written 'Fire Risk Assessment' and 'Emergency Plan'.  This must be periodically reviewed.

The local fire brigade can enforce compliance, and close any building that does not meet this act.

In the event of a fire in a building without a written 'Fire Risk Assessment', those responsible may face fines and imprisonment, and/or private litigation.

What the law requires you to do:

  • Complete a fire risk assessment for your work place (considering all employees, the public, disabled people and people with special needs.
  • Identify and record any significant finsings or persons at risk.
  • Provide and maintain fire precautions.
  • Provide information, instruction and training.
  • Nominate persons responsible to implement your emergency plan.
  • Consult employees about the above nominations and your proposals to improve fire precautions.
  • Inform other employees who may have work places in the building about any significant risks which may affect their safety and co-operate with them to reduce/control these risks.
  • If you are not an employer, but control premises which contain more than one workplace, you are responsible for complying with fire regulations.
  • You must establish a suitable means of contacting the emergency services.
  • Your employeees must co-operate to ensure the workplace is safe from fire and its effects.

System Zoning Information

In order to aid identification of the source of a possible fire, the protected building should be divided into 'zones'.  When deciding on a suitable zoning scheme for a building, consideration should be given to the size, any existing fire routines, escape routes, zone accessibility, and structural fire compartmentation.

The following guide lines should be observed:

  • If the total floor area of the building is less than 300m2 then the building needs only one zone, regardless of the number of storeys.

If the total floor area is greater than 300m2:

  • The maximum area for a zone is 2000m2
  • If a stairwell (or similar) extends beyond one floor it should be a sperate zone.
  • If a zone covers more than one fire compartment then the zone boundaries should follow the compartment boundaries.
  • The search distance within the zone in order to ascertain the position of the fire should not exceed 60m.  Remember that the use of Remote Indicator lamps may help to reduce the distance travelled.

  • If a building is divided between occupiers, zones must not be shared between them.

Manual Call Points

A 'Manual Call Point' is a device which enables personnel to raise an alarm in the event of a fire incident by pressing a frangible element to activate the alarm system.

Manual Call Point should be installed at a height of 1.2m above floor level at easily accessible, conspicious positions, on exit routes, at the entry floor landings of staircases and at all exits to the open air.

Manual Call Points should be spaced so that one may always be found within a maximum distance of 45m apart or 25m for disabled person.

Automatic Detectors

When deciding on the type of detector to be used in any area it is important to remember that the detector has to discriminate between a genuine fire and the normal conditions existing therin.

Detector Information

Smoke Detectors

In open spaces under flat horizontal ceilings, every point should lie within 7.5m of a smoke detector.

Smoke dection should be generally avoided in the following areas to avoid unwanted alarms.  They should  be protected by means of other detectors such as heat detectors.

Contamination in dusty areas may cause unwanted alarms and reduce the life of the detector.

Damp or humid conditions such as showers, bathrooms and external areas should be avoided as the water vapour may cause unwanted alarms and reduce the life of the detector.

Detectors should never be used at low temperature where ice or condensation can affect detector sensitivity.

Kitchens, garages, welding shops and boiler houses should generally be avoided.

 

Heat Detectors General

In open spaces under flat horizontal ceilings, every point should lie within 5.3m of a heat detector.

Heat detectors are designed to either detect a rapid rise in temperature or to operate at a fixed temperature.  Although they provide a slower response time than smoke detectors they do provide a method of protection for areas where smoke detectors cannot be used.

Heat detectors should not be used for the protecion of life or where extensive property loss may be expected.

'Rate of Rise' Heat Detectors

'Rate of Rise' heat detectors respond to both rapid increases of temperature and to fixed top temperatue.

'Fixed Temperature' Heat Detectors

Fixed temperature heat detectors are available with different temperature settings, and are normally installed in kitchens, boiler rooms, etc.

Detection In Apex Roofs

If the ceiling is pitched or sloping, smoke will tend to rise towards the highest point (apex) of the roof, therefore detection should be placed in the apex.  As the slope tends to reduce the delay before smoke or heat reaches the detectors, it is permissable to use a greater spacing between the detectors mounted there.

Limits of Ceiling Height

Fire Alarm Sounders

Fire Alarm Sounders should be installed throughout the building with an even distribution, to generally provide a minimum sound level of 65dB(A) or 5dB(A) above any background noise which is likely to persist for more than 30 seconds.

Where the alarm may have to arouse sleeping persons e.g. Hotel bedrooms, nursing homes, etc, a minimum sound level of 75dB(A) is required, at the bed head with all the doors shut.

All fire alarm sounders in a building should produce the same sound, distinct from any other audible warning devices in the building.

Where fire alarm aounders are required in extremely noisy areas e.g. Machine shops, it may be necessary to install additional 'Visual Indication Beacons'.

Cabling

The operation of a Fire Alarm and Detection System' depends on the cabling and connections between the components.  It is essential that connection between Manual Call Points and Detectors function correctly when they are operated.

Cables within the system are required to function correctly for significant periods after being attacked by fire.  These include the power supply cables to the control panel, the detection circuits and the fire alarm sounder circuits.  Thus the cables chosen must be correctly rated to withstand these conditions.


http://www.eurotechfire.com/bs-guide.aspx

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