fire alarm heads

[mcm]

does anyone know the requirements for fire alarm heads ie the distance in the rooms and of walls in which they can be positioned.

thanks

 

[sparks1234]

Yes
But it isnt that easy to explain, best way is to look it up in BS 5839.
Also, if you are looking to install fire alarms then there are strict regulations that you become responsible for making a decision on and need to be able to back your decision for installing fire alarm hardware where you have.
Tread very carefully, its all fine till it goes wrong.

 

[accordfire]

does anyone know the requirements for fire alarm heads ie the distance in the rooms and of walls in which they can be positioned.

thanks

Well, in simple terms, 500mm from any "edge" - e.g. wall, obstruction in the ceiling such as a duct.

Smoke detection covers a 7.5m radius - therefore, you should build up a "grid" pattern placing a smoke detector every 7.5m in each direction.

Heat detection covers a 5.3m radius - and therefore you would build up the grid as above using a heat detector every 5.3m.

There are many other considerations, however, such as compartmentalisation, environment, level and category of detection required, to name a couple. Easy areas that can trip people up are around lifts, stairwells, light fittings, air conditioning, and so on.

Also, the "rules" vary slightly depending upon the type of building you're working in, and the type of system being installed, as in some cases part 6 of BS5839 will apply, and in the majority of cases, part 1 applies.

I'll give you the advice I give everyone else. Design of a fire alarm system is NOT something you can take chances with, and NOT something you can do on the back of a smoke packet.

Spending a couple of hundred quid on a properly certificated design CAN and HAS saved lives. Thorough knowledge of the standards, and the myriad related legislation and practice isn't something you pick up in minutes, but can save lives.

Installing a fire alarm in the wrong manner can cost as many lives as doing it right can save. Routine maintenance is required for compliance with the British Standard. And both have a big part to play in the overall worth of the system.

If I charged the same rate for design of a system as I did for attendance to a system incorrectly designed, I'd be writing this post from my very own island in the Bahamas, or paying someone else to write it while I was there.

I will be totally honest - I have a sense of humour about almost everything this world throws at us. It fails completely where fire safety is concerned. My advice is always don't cut corners, and don't take a chance if in any doubt at all.

That certificated design can save you as much as the people the system was designed to protect.

 

[mcm]

Im only moving a head due to suspended ceiling coming down. In the room its only about 5m by 3m square, their is light duck in middle and a bulkhead witch covers a quarter of the space. The original ceiling is sloped so were should it go. Up the top of the slope or still 500 hundred from all walls. Thanks

 

[accordfire]

Im only moving a head due to suspended ceiling coming down. In the room its only about 5m by 3m square, their is light duck in middle and a bulkhead witch covers a quarter of the space. The original ceiling is sloped so were should it go. Up the top of the slope or still 500 hundred from all walls. Thanks

Have you got a photo?

Sounds like it should have two detectors for proper coverage - the bulkhead being the major issue.

Depending on the pitch of the slope, depth of the bulkhead, and size of the light well is what will determine proper coverage.

 

[mcm]

The light well is in the middle and the depth of the slope is about a meter to the bulkhead. On the bulkhead ceiling it is made of suspended ceiling with two grid lights in so no room to fit detector. Thanks

 

[accordfire]

The light well is in the middle and the depth of the slope is about a meter to the bulkhead. On the bulkhead ceiling it is made of suspended ceiling with two grid lights in so no room to fit detector. Thanks

Hmm.

You may get away with one on the raised side of the light well, close to it.

Is this an L1 system, or L2?

You may need to fit an additional detector in the void above the bulkhead and a remote indicator if you can't get one on the ceiling tiles.