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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Technical Advice => Topic started by: Graeme on April 05, 2005, 10:43:18 PM
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I have been on a couple of sites recently and noticed that a few rooms have had the ceiling quartered by exposed H-beams.
In the middle of the room was one smoke detector.The beams are greater than 10% of the ceiling height so i would have counted them as a wall and had a detector in each section.
The only thing i noticed that the beams are different to the normal type as they had(and excuse description without a picture) large hexagon holes along their length.I guess for cosmetic looks maybe?The top of the hole would be approx 40mm from ceiling.
Is there any reason to discount these beams as four seperate walls or do the holes make a difference?
I would say no but would like to be sure.
Thank you
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I've not got the time to re-read the BS, but if the barrier to smoke movement is only 40mm from the ceiling, I would be inclined to say it was OK. (Speculation.)
The hexagaonal holes are most probably not cosmetic, I can't remember the term for it, but it is a common way to increase the strength of a H-beam to cut it and then weld it in a manner that produces this appearance.
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castellated beams christopher, castellated beams!
in making this post i would like to make clear that i have no interest in the manufacture, distribution or installation of these beams, and apparently no beams are hurt in the making therof.
dave bev
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Now, if I were not such an honest person I would now delete you post and edit mine. :):):)
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Aren't these Chinese beams with their testes removed, Davey?????
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far too much time on your hands mr todd!
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I've not got the time to re-read the BS,
as far as i am aware according to BS a beam greater than 10% of final ceiling height should be regarded as a wall.It does not go into detail of types.
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I've not got the time to re-read the BS,
as far as i am aware according to BS a beam greater than 10% of final ceiling height should be regarded as a wall.It does not go into detail of types.
I also believe this to be true.
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anyone shed some light?
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Have another one.
A room far less than 100m2 with a sloping roof. 4 H beams run from the lowest point to highest.
At the highest point the beams are less than 10% of ceiling height but at lowest they are more.
A detector in the apex will cover the whole room,so do i count the highest point as final ceiling height and discount the beams?
Thanks
Graeme
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Do you lie awake at night making these up Graeme??
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Is the sloping roof less than 600mm high along the upright from its lowest point to peak? If so then (as you know) you treat it as flat so therefore the beams are dividing "walls". Otherwise in the apex (or within 600 mm will do.This of course all relates to the maximum height that the sensing element can be from the ceiling (in the case of a smokie!!)
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Yes, you do , as that is where the smoke ends up anyway.
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Do you lie awake at night making these up Graeme??
not this time as this was a room i looked at last week.Although it has popped into my dreams recently.
Thank you Colin and Buzz
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Colin
please can you clarify an ammendement to BS5839-1 regarding siting detectors within 1.5mm of lift shatfs etc [accomodation areas].
does this mean now only in areas where people stay? It seems like a daft obvious question but i like to be sure,
Thanks.
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No, Graeme. I know you will not believe this as I still find it hard to do so, but allegedly some fire alarm people could not work out if these detectors were to go INSIDE the lift shaft or outside. So the use of accommodation is meant to help the educationally sub-normal reader work out that no, you dont put them inside the lift shaft, so stopping the lift from going up and down, but you actually put them OUTSIDE the shaft in the ''accommodation''. Dont blame me please. I am only the messenger of such nonsense.
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Thanks Colin.It was one of those things that seem obvious when you read it out but still makes you think.
never thought of putting one in the lift shaft.Apollo don't make a floating one yet.
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Thanks Colin.It was one of those things that seem obvious when you read it out but still makes you think.
never thought of putting one in the lift shaft.Apollo don't make a floating one yet.
Have seen and maintained detectors at the top of lift shafts AND situated at the bottom!!!
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as in buildings such as games halls and farm barns etc with steel beam construction where the roof does not sit flat on the beam but has a gap. Is the gap i.e 150mm big enough to allow free passage of smoke across the ceiling under the beams?
Thus discounting the beam as a wall which is bigger than 10% of ceiling height or do i still treat each one as a wall?
At present i treat them as walls but wondered if there is a minimum gap allowed
Have asked this before so apologies for being boring and curious about beams again. I do think about other things now and again.
g
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Well.If you have floor to ceiling racking or partition walling that comes to within 300mm of the ceiling then it's treated as a wall so (and I'm sure I'll get knocked back quicker than a pint of Guinness if I'm wrong!) I would say it's the same for your beams.
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Graeme you also have to watch out that over a long distance the beam has not spread out to much. It is not like a laser, and does spread out quite a bit over a long distance.
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as ever Gents-Colin and Buzzer i thank you.
I will carry on as before and treat as walls.