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smoke vent strategy
#1
All,
         whilst testing a fire alarm we encountered a problem with the smoke vents operated by the addressable fire alarm system. There are 4 smoke vents (1 for each stairwell and at the top of each 2 storey stairwell) in zones 11,14,16,17. The smoke vents are operated by 4 separate relays which are programmed to operate only by zones 16-18 after a 30 second delay. ZONES 1-15 DO NOT OPERATE THE SMOKE VENTS AT ALL. Zones 1-15 cover the majority of the ground floor and parts of the first floor of the site. Morley zx5 panel.

The problem is if you test a device in zones 16 or 17 the smoke vents nearby open but the detectors nearby the vents in zones 11 and 14 do not operate the vents in the stairwells immediately adjacent to them. 

There is no documentation on site to explain this programming and therefore we don't know why they have been set up this way. The FIA advised me not to adjust the programming until the smoke vent strategy is known. I rang COLT who installed and service the smoke vent system at this site and they couldn't give me a reason why it should be programmed this way and most smoke vents they test operate on a 'one out, all out' basis. 

My personal view is this is an error by someone during programming. I believe the vents have a 30 second delay so the vents do not operate every week on the brief weekly test but they will open after 30 seconds in a real fire. For the record the vents have metal guards around them so even if the plastic louvres of the vents open there is a physical grate to stop anyone entering the building this way. The only downsides are the minor chance of water ingress through open vents and the possibility of an unknown smoke control strategy being disrupted by these vents opening in any fire. The vents automatically reset themselves and close when the fire alarm system is reset. The vents can also be operated by a yellow smoke vent only mcp near to them in each stairwell 

Any ideas on 'standard' scenarios for when smoke vents are operated by fire systems? I tried to contact the smoke control association with no success.

ta all!
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#2
So the only vents are at the head of each staircase?

No vents through walls from protected lobbies?

If so then the vent would normally open on any fire in the staircase or if detected in the lobby opening onto the staircase.

But there are all sorts of rules for compliance depending if its a single staircase / multi staircase / 4m long corridors etc etc ...

You can try checking these out .....

https://www.cibsejournal.com/general/cle...e-control/

http://www.feta.co.uk/associations/hevac...blications
===============================
Some men aren't looking for anything logical. They can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn.
Established 1985 - 30 Years Trading - BAFE SP203 - Wireless Fire Alarm System Specialists
http://www.ctafire.co.uk
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#3
So the only vents are at the head of each staircase?

No vents through walls from protected lobbies?

As far as I can tell there are no vents through walls. Certainly no visible vents. Would these generally be visible? I could ask COLT but I'm pretty sure the only vents are at the heads of the stairwells.


If so then the vent would normally open on any fire in the staircase or if detected in the lobby opening onto the staircase.

That's what I would have thought. I've escalated it to my bosses but I don't think they'll know anymore than me and the guys on this forum!

As a side issue I guess that each smoke vent should have a smoke detector adjacent? Some stairwells have no smoke detectors in them and hence are activated by devices elsewhere.
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#4
"the detectors nearby the vents in zones 11 and 14 do not operate the vents in the stairwells immediately adjacent to them"

It can be hard to analyse without knowing the layout of the building but the quote above suggests to me that you are correct.
Royce

RoyceM@kentec.co.uk

Technical Support @ Kentec Electronics Ltd.


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#5
(08-09-2017, 01:01 PM)alonso Wrote: So the only vents are at the head of each staircase?

No vents through walls from protected lobbies?

As far as I can tell there are no vents through walls. Certainly no visible vents. Would these generally be visible? I could ask COLT but I'm pretty sure the only vents are at the heads of the stairwells.


If so then the vent would normally open on any fire in the staircase or if detected in the lobby opening onto the staircase.

That's what I would have thought. I've escalated it to my bosses but I don't think they'll know anymore than me and the guys on this forum!

As a side issue I guess that each smoke vent should have a smoke detector adjacent? Some stairwells have no smoke detectors in them and hence are activated by devices elsewhere.

There are lots of different rules depending if it's a single stair or two stair escape etc. 

Often you don't actually need a smoke detector in the stairs as it can be manual only ..... all depends on the fire strategy for the building ....
===============================
Some men aren't looking for anything logical. They can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn.
Established 1985 - 30 Years Trading - BAFE SP203 - Wireless Fire Alarm System Specialists
http://www.ctafire.co.uk
Reply
#6
Smoke control strategies can be quite complex and not immediately apparent upon simple inspection.
They are usually designed bespoke for the premises and can incorporate air movements that you wouldn't necessarily expect. I have one site that has a single "vent" at the top of the stair head, but it's an inlet rather than an 'exhaust' and is designed to alter the pressure in the stairwell to keep smoke from entering it. There are vents installed on floors 7-12 and work for certain scenarios. The lower floors have a different set up (dedicated smoke shafts serving 1-6). Under normal circumstances, the whole system is used for environmental airflow, but when smoke is present it works in a specific way, depending on where it was detected.
IFE Registered Fire Risk Assessor

www.ajfire.co.uk
01245 392014
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