installation of fire dampers

[Ricardo]

Can I ask the views of the 9999 Gurus please, at 33.4.5.1 page 168 of BS9999 it discusses 3 methods of installing fire dampers within venillation ductwork, it goes onto say that:-

smoke detector operated fire/smoke dampers should be installed in all occ characteristic Cii and Ciii buildings, "UNLESS ALL" occupants can be expecetd to make an UNAIDED escape and an L1 system is installed to 5839-1+A2 2008.

So do I take it that any building within the scope of Cii or Ciii such as a hotel, who can cater for any non ambulent/disabled person should have such provision? as clearly any building that has any disabled provison cannot guarantee an unaided escape.

So should it be a case of this provision is provided for the whole building or only disabled rooms and expected escape routes from such rooms?

As by definition for those who do not need assistance to escape, this section is not intended for them, so is it a question of coverage for the diisabled rooms and escape routes or the whole building?

[kurnal]

I think its a case of applying common sense in applying this rather confusing and apparently rather onerous recommendation. Its one of those that every time you read you could come up with a different interpretation. Heres my attempt at clarification.

Where there are ventilation ducts in Cii and Ciii - first identify those fire compartments which may be occupied by persons who need assistance to escape. All ventilation ducts within these compartments or any ducts penetrating these compartments, should have smoke detector operated fire and smoke dampers.  Take a compartment by compartment view, not a room by room view. Otherwise the very people you are trying to protect may be affected by a fire in other rooms within the compartment.

For Cii and Ciii compartments where there no occupants need assistance to escape (does such a place exist?)   AND if a L1 system is installed AND a single stage evacuation of the compartment takes place, smoke detector controlled dampers are only needed where the duct enters or leaves the compartment.


Paragraph 44.4.5.1a is particularly confusing because it seems to say that for small buildings Cii and Ciii with no compartmentsAND nobody needs assistance to escape  (does such a place exist?) AND if a L1 system is installed AND a single stage evacuation of the building takes place, no fire or smoke dampers are required in the ventilation system ducting. I am not sure about that- I think it perhaps should have said that SMOKE DETECTOR OPERATED fire and smoke dampers would not be needed.  

[Ricardo]

Hi Prof

Thanks very much for your reply, can you just clarify, you make reference to Paragraph 44.4.5.1a, I take it thats a slipped finger on the keyboard,is it? as I can't seem to find that bit. And as for your last sentence:-

"if a L1 system is installed AND a single stage evacuation of the building takes place, no fire or smoke dampers are required in the ventilation system ducting. I am not sure about that- I think it perhaps should have said that SMOKE DETECTOR OPERATED fire and smoke dampers would not be needed"

I agree with you,now that is confusing as many may take it as gospel, so how many more errors may be found in this Standard, I have come across a few myself going through it?

[kurnal]

Sorry Ricardo I meant 33.4.5.1a

Dont take it as gospel that I am right- its my opinion only. It just seems to me that in some circumstances eg ducts passing from rooms to escape routes that fire /smoke dampers may be needed in some building layouts, especially dead end conditions and staircases. But then I still cant imagine such a building as described.

[Phoenix]

Hi,

Just to chip in with my simple take on it...

Wherever an unprotected duct passes through a line of fire resistance (whether it is a line of compartmentation or just fire separation), a damper is required. 

The base level is an intumescent (or similar) type damper that reacts to heated gases but not cool smoke.  This will provide adequate separation for compartmentation purposes but may not stop the spread of cool smoke beyond the lines of fire separation. 

Where means of escape is more likely to be affected by the spread of cool smoke (for example, where people require assistance to evacuate), detector actuated dampers will react quickly to fire and stop the spread of smoke beyond the lines of fire separation. 

With that principle in mind you should now be able to apply the guidance in a manner that will satisfy all functional requirements.

Stu

[kurnal]

Hi,
Where means of escape is more likely to be affected by the spread of cool smoke (for example, where people require assistance to evacuate), detector actuated dampers will react quickly to fire and stop the spread of smoke beyond the lines of fire separation. 

And just to build on that, clearly the detector need not be in the duct, if the spaces or rooms connected by the duct all have smoke detection then this can be used to operate the damper, controlled by a simple interface box to the fire alarm system. And not forgetting to shut down any fans at the same time. 

[CivvyFSO]

Just to add on Kurnals advice, this is supposedly only suitable where air is not recirculated, according to BS5588 pt 9. (Couldn't be bothered reading through 9999 just to find the same comment.