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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Safety => Topic started by: stewbow on September 15, 2008, 03:57:58 PM
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Take for example a 3 storey Victiran house, converted in to 3 self contained flats with a communal staircase.
LACORSE says 22.14 Grade A:Ld2 coverage in the common areas and a heat detector by the entrance door in the hallway to each flat. Also recommended is a Grade D: stand alone smoke detector also positioned in the hallway of each flat.
But what about Sounders within the flats?
If you are just applying Grade A standards to the hallway of the flats, then a 65 Db Sounder would fit the bill, but this wouldn't be loud enough to travel through a bedroom door and wake a sleeping person (if the alarm was triggered in the common area)
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I think you will find it says smoke or heat alarm which is a detector and sounder combined as opposed to a separate detector and sounder in a part 1 system.
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where does it say that Jokar out of interest?
I find mixed systems a very grey area and a nightmare to get a straight answer.
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What it may or may not say is one thing , common sense is another. f it needs a common areas alarm then it needs to be heard in all relevant places. Where (rarely) I have specified such systems I have taken jokars line of a heat detector/sounder.
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We have installed many of these systems.
Although about a year ago we were also challenged on this... The property was an 8 storey apartment block. The communal areas was installed to L1 system, with the apartment having there own mains powered detectors. In each lobby of the apartments was a combined heat sensor and sounder.
The sounder was outputting around 90dB and indeed was adequate for coverage in the lounge/kitchen areas but was not achieving 75dB at the bedhead.
Now, within BS5839 Part 1 it does cross reference these systems for landlords areas with domestic properties and it does indicate that the 75dB ins't required at the bedhead only in these circumstances as there hasn't been a case where it has been proven that a sleeping person hasn't been woken.
Check BS5839-Part 1 for this... i will try an assertain the extact clause and post here.
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To save digging Big Fella, heres an extract from a recent determination by the secretary of state
"BS 5839-6:2004 suggests that the audibility of an LD3 system should provide at least 85db (A) at the bedroom door with the door open, and that no bedroom door should be more than 3m from the detector.
The commentary in the British Standard then goes on to suggest that with the bedroom door closed, sound levels of 55-65db (A) are more realistic, but even with this sound pressure level there is no evidence to show that lives are being lost.
The standard suggests that this is possibly because people in their own homes can be roused by an unusual sound of relatively low level. "
Now as to whether that is fact based on research or total speculation I cannot say. As a person who slept through the recent earthquake my gut feeling is that its probably the latter.
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Phew... That saved me some reading to find that today :)
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Graeme, just picking up on the definition of a Grade D system in pt 6 which states smoke alarm not detectot. The definition of an alarm as opposed to a detector is what I was giving.
Now I am interested though in what components formart of a mixed system, whether Pt 6 mixed or a combined part 1 and 6. For instance, if there is L4 in the comon areas and grade D in dwellings, what happens. If someone can give me further details of this and other mixed systems that would be great.
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Student 'cluster' accomodation is often a mixed system.
These are often set up like the following:
A 8-9 storey building, protected FF stairs etc where they need to be. Off these stairs you have a protected corridor. FD30S (Sometimes FD60S) doors lead from this corridor into a "cluster". You pass through that FD30S/FD60S door and you are in a common area, or another mini corridor running parallel to the main corridor, that has 4 or 5 en-suite bedrooms off it and a kitchen, all FD30S doors.
Each of these clusters of 4 or 5 is classed as a seperate dwelling, they have their own part 6 system in the common areas, the kitchen and the bedrooms. All SD apart from HD in the kitchen. This alarm only serves to warn the people in that cluster in the event of an alarm activation in the cluster, and they have the facility to silence/reset their own alarm. Neighbouring clusters stay put if this system activates..
Now outside the cluster you have a Pt 1, generally an L2 or L3 system, but that entails 1 HD that belongs to this system being situated in the common area/mini corridor. Only the operation of that HD or any other part of the pt 1 will alert security, and may initiate an evacuation.
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Ok so there is no linkage between the part 1 and part 6 system and they both act independently. What about a part 6 mixed system, do they act independently as well?
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If the building has been converted into self contained flats I don't see why a fire alarm system is required in the communal areas? Does the building not provided adequate compartmentation?
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It should do.
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If it does provide adequate compartmentation then no fire alarm is required.
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Correct.
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I know
Mutual backslapping in progress
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Student 'cluster' accomodation is often a mixed system.
These are often set up like the following:
A 8-9 storey building, protected FF stairs etc where they need to be. Off these stairs you have a protected corridor. FD30S (Sometimes FD60S) doors lead from this corridor into a "cluster". You pass through that FD30S/FD60S door and you are in a common area, or another mini corridor running parallel to the main corridor, that has 4 or 5 en-suite bedrooms off it and a kitchen, all FD30S doors.
Each of these clusters of 4 or 5 is classed as a seperate dwelling, they have their own part 6 system in the common areas, the kitchen and the bedrooms. All SD apart from HD in the kitchen. This alarm only serves to warn the people in that cluster in the event of an alarm activation in the cluster, and they have the facility to silence/reset their own alarm. Neighbouring clusters stay put if this system activates..
Now outside the cluster you have a Pt 1, generally an L2 or L3 system, but that entails 1 HD that belongs to this system being situated in the common area/mini corridor. Only the operation of that HD or any other part of the pt 1 will alert security, and may initiate an evacuation.
Civvy would there be any ventilation to the staircase lobbies as per the design of flats in this scenario?