Zoning of fire alarm system

[Davo]

Premises
3 storey plus basement, oblong with centre stair and internal stair one end external other end.
Two of the floors have one room within the centre staircase enclosure, fully FD30S' d up with corridor FD30S either side.

My question is

Should that room be in the staircase zone or the floor zone

Its not mentioned in 5839 and I have no other guidance from the great man, or inded other great men, to assist

cheers

davo.

[Davo]

DC

Yes, directly onto the stairs

davo

[kurnal]

Hi Davo
Is it a conventional or an addressable system?

Presumably we are talking about a system that incorporates automatic detectors.

I guess it's much less important with an addressable system but we should remember why stairwells are usually treated as a separate zone in their own right. If there is a fire on the ground floor and smoke enters the staircase it will rise up and as there are likely to be detectors on each landing level each will operate in sequence as  the smoke rises.

If the detectors in the staircase were linked to the zone covering that particular floor you would very quickly be given the impression that all floors were involved in fire. That would be very confusing. So to avoid this the staircase is treated as a zone in its own right.

But as David says one fundamental reason for creating detection zones is to support the quick and easy investigation of alarms. And provided you meet this requirement I don't think it really matters which way you configure it. And it's less important still if it's an addressable system.

My gut feeling is that the room leading off the staircase should be part of the zone covering that particular floor. But as always happy to be corrected if someone knows better.

[Davo]

Each floor wing is about 25M long, central corridor and rooms off, say 30 per floor in all.
I just thought it might be simpler to stick the room in the stair zone, one of the two doors has GW glass panel so it would be obvious it was the other room.
However as always I will defer to those with better knowledge, especially those who have done the job!

davo

[Davo]

L1 system Prof, 2005.
Each floor is one zone.

davo

[SamFIRT]

The idea is to guide the fire brigade to the fire, therefore they will want to be guided to the door of the room where the fire is contained.
Therefore it would seem logical to put the two rooms on the staircase zone rather than the floor zone.

Works for me. 

[Wiz]

Staircases (and other risers in a building) should have their own zones.

Rooms leading onto that zone can also be part of that zone (unless the total area covered would exceed 2000m2) but they can also be their own zone(s).

However if you are standing in fire zone X, you should never have to travel through another zone to reach a different part of zone x

[Graeme]

Hola Wiz


Just to clarify for my own interest. example

A building has a central stairwell that goes from ground to 1st floor. Both floors have other areas that you have to go through the stairwell to reach on the same floor. So from what you have said-should the other rooms be on individual zones?

and this is an addressable system.

13.2.3 Additional recommendations applicable to detection zones that contain non-addressable automatic fire detectors

c) Automatic fire detectors within any enclosed stairwell, liftwell or other enclosed flue-like structure should be considered as a separate zone.


 i have always been uncertain what exactly  makes for an enclosed stairwell?  1 door in at each floor? or a stairwell with lots of rooms off it but when doors are shut is enclosed?

.

thanks

[David Rooney]

By "rooms within the staircase" I'm imagining small rooms off the staircase opening directly onto a landing, in older buildings these might have been WCs or kitchenettes of sorts.

Personally if the system were addressable and the rooms are fitted with detectors as they would have to be for an L3 + system I'd put them on their own zone.

Otherwise I'd include them in the stair case zone simply as the search distance would be much smaller and more direct.

[Wiz]

Hola to you back, Graeme,

I've been on holiday, so only just seen your post. Sorry for the delay in responding.

My understanding is that the use of the word enclosed with the word stairwell is only to differentiate it from those sort of stairs that may be found in otherwise open areas. Say from the ground floor to a balacony in, say, a big library reading room or similar.

The idea of making the detectors at various levels in these enclosed staircase areas part of the same fire zone is surely to avoid the confusion of the smoke from a fire on a lower level reaching a detector on a higher level whilst by-passing one or more detectors on intermediate levels. If all these detectors were actaully on different zones relating to the various floor levels and as part of those zones that were extending beyond a door between the staircase and, for example, a corridor, it could be very confusing working out on which level the seat of the fire existed from viewing the operated zone indicator.

In my opinion if there is no door between the stairwell and the corridor then I believe all the detectors in that corridor should also be on the same zone as the stairwell detectors. This scenario is hardly likely because there is normally always a fire door pretty close to the actual stairwell and which would form the fire zone boundary of the stairwell zone.

The question you raised before was what if there was a room that led straight onto that stairwell at one level. You wondered if that room should be part of the stairwell zone or the floor zone. I think it could be part of the stairwell zone, although it might be less confusing if it had it's own zone entirely (if possible). But this sort of room probably shouldn't be part of the zone that starts the other side of the door to the stairwell at that level, because then you would have to travel through the stairwell zone to reach two separated parts of the same zone when searching for a fire condition and it may confuse people trying to establish where the boundaries of zones are.

[Allen Higginson]

If they directly open onto the stairwell then they are on the stairwell zone (in my opinion),in the same way as if the MCP's are located in the stairwell on each floor they are on the stairwell zone.

[Wiz]

Agreed Buzz, but they could also be on their own zone(s) (space permitting) for even less ambiguity as to the 'seat of the fire'.

[Allen Higginson]

Agreed Buzz, but they could also be on their own zone(s) (space permitting) for even less ambiguity as to the 'seat of the fire'.

Have seen this pushed to an extreme on an old 2 loop (fully loaded) Android addressable panel where each device was on it's own zone (installed by a company that was better known for intruder at the time).

[Graeme]

in the same way as if the MCP's are located in the stairwell on each floor they are on the stairwell zone.

would you not have them programmed on the same zone as the accomodation side?

[Allen Higginson]

in the same way as if the MCP's are located in the stairwell on each floor they are on the stairwell zone.

would you not have them programmed on the same zone as the accomodation side?

Only if they are installed on that side of the door G.