Point detectors in industrial environments

[Owner]

We are the owners/operators of several large industrial premises and are having another facility being built on a ‘design and build’ basis.  The new facility is extensive – it is an open space about 160m long by 100m wide by 6-8m high, and the processes are such that it will be fitted out with smoke detection, sprinklers and smoke extraction.  Upon completion, the facility will be handed over to our maintenance contractors. The processes being undertaken – storage and basic cleaning of large pieces of mobile plant - will generate a fair amount of dust (no significantly wet processes will be used and no internal combustion engines will be run).   The facility is intended to operate for 24 hours a day, 7 days a week.

The design/build contractors are offering us a detection system that uses point detectors.  We are concerned that maintenance of so many detectors at the intervals specified in BS 5839-1 will be uneconomic and unnecessarily disruptive to our operations, especially as they are likely to get dirty fairly quickly, and that there will be a potential for a significant number of false alarms.  We have one other facility of a similar nature, where we use video smoke detection – we would prefer to have this type of system in the new facility as well.  The Contractor is refusing to accommodate our wishes, saying that the point detection is fully compliant with BS 5839-1.  They appear to be unconcerned at the cost of maintenance and the disruption to our operations it may cause.

Forgetting the ethics of their attitude, can any of you ‘gurus’ suggest whether there is anything in any British Standards that we can use to try and convince them that they are not complying with their contractual obligations to supply us kit compliant with those standards?  I thought that CDM may be of use, but it would appear that because the kit can be maintained safely (if not economically), they are off the hook?

Any advice would be very greatly appreciated.

[Allen Higginson]

As a rough calculation and not knowing the bulidings structure (ie - beams,apex etc.) you would be talking a minimum of 160 smoke detectors on a flat or minimum gradient roof (based on the 10m by 10m coverage of each detector).Are beam detectors not an option - taking that it is no more than 100m wide then you could use 11 beam detectors along the 160m side, spaced at 7.3m from both walls of the 100m side at 14.5m intervals (I think that adds up - I'm sure it'll not be too long before someone points out my mistake and I'll have to change my screen name!)

[Owner]

Interesting idea - or it would be if they were willing to consider giving us anything but point detectors.  What they are saying is "you are getting point detectors and that's that".  As I say, forget whether this is a 'customer focussed' response or not (because it certainly isn't) - the question is whether there are any standards / guidance / codes of practice that encourages them to give us a system which is economically maintainable, when they have no apparent interest in doing so!

[Chris Houston]

To comply with the BS, you must consult with your insurers as well as various others - see section 1, page 13, paragraph 6.2 a.  If point detectors did not meet with their approval, for any reason, this could be an angle?

I would also look into the beam detector suggestion, it might even be cheaper for the contractor to provide!

[Graeme]

From an installers point of view beams are far less labour intensive,easier to install than having to wire many point detectors.
You may not have the scaffolding costs,less wiring and easier to maintain.

Maybe your contractors are unfamiliar with video/flame detectors so are not willing to try it.

[Allen Higginson]

Interesting idea - or it would be if they were willing to consider giving us anything but point detectors.  What they are saying is "you are getting point detectors and that's that".  As I say, forget whether this is a 'customer focussed' response or not (because it certainly isn't) - the question is whether there are any standards / guidance / codes of practice that encourages them to give us a system which is economically maintainable, when they have no apparent interest in doing so!

It's a pity that your height doesn't exceed 10.5 metres as they wouldn't be suitable.
I take it is an addressable system that they are installing?Make sure that when they come to install it that they have split the area into 8 zones (minimum). As your total area is 16000m2 and a zone cannot exceed 2000m2 for automatic detectors that is the least you will need configured. It doesn't matter whether it is conventional or addressable - zone sizes and designations are the same.
With reference to the video detection there is no standards in 5839 for this but it does acknowledge its existence and use in special applications.
If you don't mind me asking - how are you stuck with these guys??Just done a quick calculation on equipment cost and theres not much difference in the cost of the addressable point detectors and the beams but obviously the cable installation and termination is astronomical on the former.Conventional heads are more than half the price of both but cabling is still crazy.Sounds like you've got a right bunch of minkeys (thank you Clouseau for that typo.!!)

[Chris Houston]

Well, if they quoted on the basis of simply complying with 5839 as they saw fit and have now been told the client wants video detection, I can somewhat sympathise with the contractor.  The specification ought to have been more specific.

Just to muddy the waters further, if the place is fully sprinkler protected, why not just have signaling from the sprinkler system.  Would it not operate just as quickly as heat detection anyway?

[Graeme]

maybe they want quicker detection than heat,which takes an actual fire to be detected?

[Allen Higginson]

Well, if they quoted on the basis of simply complying with 5839 as they saw fit and have now been told the client wants video detection, I can somewhat sympathise with the contractor.  The specification ought to have been more specific.

Just to muddy the waters further, if the place is fully sprinkler protected, why not just have signaling from the sprinkler system.  Would it not operate just as quickly as heat detection anyway?

Well,yes but in the original post it has specified point smoke detection.If the original specification did state to 5839 then the video detection would not comply (as I have said,it is's existence is acknowledged but not not specified a standard).Regardless,if the contractor is persisting in using point detection then you have to take it for one of two reasons - (1) They are not fully aware of the options available to them and so are sticking with what they know,which begs the question as to why they are doing a fire installation or (2) They're trying to get the money on the installation of the cable,with each cable run,through box,stuffing gland and P clip they can muster.
Or am I just getting cynical in my old age??
I do agree that sometimes the spec. can be unclear - not the first time I've been asked to design for a 5839 job and the client not knowing what level that they wanted.So you design it to L1 and they think that you're over-egging it!!

[Owner]

First - thanks for all your responses - the users of this BBS rarely fail to respond and the debate is usually illuminating!

For the sake of clarity, the premises is fire engineered and the suppliers of the new facility as a whole employed a team of fire engineering consultants to produce a fire safety strategy supporting their design.  We are stuck with them, as we do not employ them directly.

Their consultants specified the Category of the system to be installed and the use of point smoke detectors.  They design the building, build it, including all the services, then pass it over to us to operate.  They appear unconcerned at the cost of supplying/installing the system, as are we, because we do not pay any extra if it is expensive to procure and install.  

HOWEVER, they don't appear to care that, once they hand it over, it will be (so my maintenance contractors tell me) a costly and disruptive nightmare to maintain!  Try as I might, I cannot find any way, either contractually or based upon BS/EN standards, codes of practice etc, to force them to give us something that is economically maintainable.  I am coming to the conclusion that we shall be faced with ripping out this brand-new system and replacing it with something that we can maintain without jeopardising our operations.  I was hoping that there was some standard - maybe not specificlly related to fire systems - that obligated the suppliers of engineering to consider the practicability of its maintenance during their design process.

PS the insurers appear only concerned that we have a system which complies with all the relevant standards.

[Allen Higginson]

Sounds like a bad bit of engineering but looks like your stuck with it.
As far as the maintenance goes, could you go with more frequent visits (over the standard quarterly) which would mean that,yes the contractor is in more often,but is in for a shorter time each visit.Say they came in on the first of each month and tested 14 detectors ~(based on my assumption of 160 detectors) - over the year all the detectors will have been tested.Whatever callpoints you have would also have to be included over the visits but it would keep the time on visits down.Most companies work on the basis of the annual charge for the maintenance and divide it by the number of visits so it shouldn't cost more for increased visits.

[eddy orr]

Does the system comply with BS5389-1?

The reason I ask is that if there are 160? detectors and the area is dusty the nos of potential false alarms could be high.
The designer should have assessed the likelihood for false alarms early in the design process to ensure that the frequency is sufficiently low.
"34.2 Recommendations
The following recommendations are applicable:
a) at the design stage of every system, there should be formal consideration of the potential for false
alarms, with a view to confirming that design is such that the frequency of false alarms is likely to be
acceptable;
b) any relevant design information regarding false alarms should be recorded and documented in
accordance with the recommendations of Clause 40"

If the nos of false alarms is sufficiently low, it may be in your interest to look at the principles for the selection of detectors

"21.1.7 Choice of fire detection principle
No one type of detector is the most suitable for all applications. Final choice will depend primarily on:
— the speed of response required (to satisfy the fire safety objective);
— the need to minimize false alarms;
— the nature of the fire hazard.
However, other factors, such as cost, suitability for the environment and maintenance requirements might need to be considered. In some circumstances, a mixture of different types of detector may be appropriate to optimize speed of detection or to minimize false alarms.
.......................Optical beam smoke detectors can prove economical and effective for the protection of large, open plan spaces
with relatively high ceilings (e.g. warehouses), particularly if access to point smoke detectors for
maintenance could present practical difficulties."

and finally

"21.1.8 Recommendations
The following recommendations are applicable.
a) The type(s) of fire detector used in a system should provide adequate protection of occupants, property
or both, as appropriate to the Category of system, while minimizing the risk of false alarms as far as
practicable (see Section 3). In case of doubt, there should be early consultation between all interested
parties (see Clause 6). Maintenance requirements for different types of detector should also be taken into
consideration, along with any special requirements of the user (e.g. regarding the impact of the fire
detection system on aesthetics)."

Hope this is of use

[Colin Newman]

I'd check the CDM angle again.  Just because the detectors CAN be maintained safely, given the potential for disruption to operation is it reasonably foreseeable that the detcetors MAY NOT be maintained safely?  i.e. is it possible that to avoid the operational difficulties maintenance personnel may be tempted to cut corners and adopt potentially unsafe working practices?

I this is the case the CDM regs could be used to lever a more acceptable solution.

:-)

[Owner]

Update - they are now considering offering us aspirating smoke detection - this will operate a single-stage alarm & zoned smoke control.  I am still concened about maintainability & reliability.  Any 'Gurus' comments on this are most welcome!!!

[Graeme]

for a dusty warehouse!!!!

Aspirating systems are super sensitive.