Fire Alarm Certification

[David Rooney]

We have been asked to look at a recent install with a view to verification of the system, whereby the consultant has specified an L1/P1 system, under the influence of the insurers.

Within the building point smoke detection has apparently been installed on a 15m (ish) high ceiling in a large open plan space - 150mx150m give or take.

This is just about ok for Property Protection, but is too high for Life Safety (10.5m).

How should this be recorded, bearing in mind the client is expecting an L1 system without variations, and the Insurance Company expect a P1 ?

Technically I know beam detectors could have been used to satisfy both L1 and P1 at this height, but I am just interested in other opinions as to how "big a deal" this is.

Thanks

[kurnal]

David
Sounds like you're on a bit of a hiding to nothing if you have inherited the system and now need to verify it.
You appear to have been more diligent than the installer but I guess whilst the owner wants a cert to total compliance he doesn't want to make any changes?
So its down to why has the L1 been specified, is it in compensation for shortcomings elsewhere- part of an engineered solution in which the available safe evacuation time has been calculated based on the earliest possible detection of fire? If so then the detector height may be an issue but otherwise I would also consider the purpose group, the use of the space,  the fire loading and the type of fire that is most likely to occur.

The BS does tend to be a little prescriptive for good reason but the effectiveness of a detector depends on a lot more than just storey height.

I see no problem in recording variations to the BS provided it can be justified on a risk approach rather than for convenience. I also see no problem with a qualitative judgement being made rather than hard sums to calculate time to detection if this were indeed possible. The calculation would be good for a narrow set of parameters, the qualitative judgement could take account of the widest range of factors.

[Reg]

But surely David's role is to verify it to a specified standard - does it comply or doesn't it - simple.  If it doen't comply he states why not.  He has no need to justify, vary or risk assess anything.  

All that needs to be done by the original designer of the system.  He's the one thats made the mistake.  He is the one to make the corrections.  Then when he produces the correct design specification, the system gets modified against that agreed specification.   David audits the system against that specification.  Job done.

Thats the whole point of verification

[Graeme]

don't get the L1/P1 spec.

If the insurance is asking it's usually a P and to add life protection it would be P1/M

[David Rooney]

Regarding the Spec, the client has specified an L1 system, the Insurance has specified a P1 system.

Two bodies with two different objectives.

These have been brought together in a package to the installation company as an L1/P1 system.

It may well be wrong but I've seen it a hundred times in a hundred different specs.

5.2 Recommendations
The following recommendations are applicable.

g) Where the objectives of more than one type of system are to be satisfied, the system should be described
as a Category X/Y system (e.g. L2/P2 or L3/P2, etc.).

Normally there is no real conflict, in this case the ceiling height makes the difference.

Regarding the building layout, the areas vary from "warehouse" open plan style to "power station" style with lots of metal gantries and platforms, like a scene from "Aliens"...

[Thebeardedyorkshireman]

Hi David

I agree with Reg. I would, however be cautious with the 'mistake' lable untill such time as I had sight of the designers notes and certificate. If this is not forthcoming, then list the variation under the L1 reference for height. If however there is sufficient justification under the designers certificate (highly unlikely) you could cross  reference it. In this way you fulfil your contractual obligations as the verifier and allow those who have been paid to design the system an opportunity to explain their actions. You dont have to agree with them but you have to express your opinion on the wording of the BS. If as a result of this they find themselves in a contractual hole, they may think twice next time they think they know how to design.
Whilst I dont wish to spark a debate on the old dilution/stratification front, it may be possible under certain circumstances/constraints to seriously increase the sensitivity of point type annalogue smoke detectors to compensate for height. The height itself becomes the factor which reduces the false alarm problems normally encountered. See 22.1 commentary. Maybe the designer was thinking along these lines which is why I thought you may consider his view before using the mistake tag?
Lots of steelwork can preclude beams, some processes can preclude aspirated and then as a designer you have to think out of the box. In the end he probably just cocked up


Dave

[David Rooney]

Thanks all, I don't like to critiscise others for the sake of it, but tend to agree that this is one occassion when the guy did just "cock up" !

All I can do realistically is quote the regs and make sure the client is aware of the possible implications. The ball is then in their court to accept the variation or not....

Thanks again to you all.