Smoke Detector Spacing

[Mike Buckley]

Just to add a bit of spice to the mixture, bear in mind that, although LPCB does do the standards testing etc., some insurance companies, FM Global for example, want to apply their own standards which are more stringent than LPCB.

Fun, fun fun!

[Chris Houston]

Yes, they might, but I suspect most UK insurers would accept the former.  It's probably only at the high risk end of the market where this would be an issue.

[mahzad_sha]

Can anyone give me some guidance about what is the relation of smoke dedetector spacing and celling height?is there any table for that?

[Chris Houston]

Can anyone give me some guidance about what is the relation of smoke dedetector spacing and celling height?is there any table for that?

That's not really how it works.  British Standard 5839, Part 1, 2002 contains all the recommendations.

The general idea is that the approved smoke detectors should be considered effective to cover a circular area with a radius of 7.5m. It is easier to relate this to a 10m x 10m grid.  The height at which they are effective is a separate matter, not connected to the radius.

[Gel]

I have posted some NFPA data on issue at:

http://www.kiddefyrnetics.co.uk/utcfs/ws-405/Assets/NFPA%20Smoke%20alarm%20spacing.pdf

May add to debate.

[mahzad_sha]

MAY I ASK MY QUESTION IN A DIFFERENT WAY?
I MEANT WHEN WE HAVE 2 ROOMS ONE WITH THE HEIGHT OF 2 m , THE OTHER WITH THE HEIGHT OF 8 m & BOTH ARE 50 m2 ,DO WE HAVE TO USE 1 SMOKE DETECTOR FOR EACH ROOM?
THANKS FOR YOUR HELP

[Chris Houston]

Assuming detection is necessary, assuming the rooms are approximatly as long as they are wide, assuming the detectors are EN54, then yes.

[philex]

what is the spacing between smoke detectors???
what is the spacing between water sprinkles???

[kurnal]

smoke detector spacing depends on the shape of the space the detectors are to be installed in- a 7.5m radius of operation is normal but there are variations depending on whether its a  room or corridor and the shape of any ceiling if not flat, and any beams or obstructions..

Sprinkler spacing depends on a number of factors in the same way - there are ceiling sprinklers and in rack sprinklers, and the spacing is normally about 3m for ceiling sprinklers but again they  may be closer if there are obstructions. In rack sprinklers tend to be closer spaced horizontally and vertically.

[Allen Higginson]

Basic rule of thumb for your standard room is that a detector will cover 10 square metres (10 by 10).As kurnal has stated though it can increase due to pitch of roofs etc.

[Thebeardedyorkshireman]

Is that not 100 SqM?

[Wiz]

Basic rule of thumb for your standard room is that a detector will cover 10 square metres (10 by 10).As kurnal has stated though it can increase due to pitch of roofs etc.

The 'rule of thumb' is really just for a quick estimation of how many 'point' detectors an open area may require. You divide the area (in square metres) by 100 for smoke detectors and 50 for heat detectors. Precise detector location by using all the recommendations in BS would then be necessary to ensure correct coverage.

[Allen Higginson]

Is that not 100 SqM?

Stands in corner with pointy hat on!

[Allen Higginson]

Basic rule of thumb for your standard room is that a detector will cover 10 square metres (10 by 10).As kurnal has stated though it can increase due to pitch of roofs etc.

The 'rule of thumb' is really just for a quick estimation of how many 'point' detectors an open area may require. You divide the area (in square metres) by 100 for smoke detectors and 50 for heat detectors. Precise detector location by using all the recommendations in BS would then be necessary to ensure correct coverage.

110% in agreement - just so happens that I was specifying for a nice 78m by 35m open area where beams are not an option!