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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Safety => Topic started by: shaunmckeever on April 01, 2006, 12:03:51 AM
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I have a building I am advising on. The building is listed. It has a single staircase and has 8 floors including ground and basement. Access to spaces off of the staircase is via single doors at each level. The doors are part of the listed status and do not provide any comparison to modern day fire doors. They are not fitted with intumescent strips or cold smoke seals. The building is multi-occupancy with the lower floors (B, G, 1 & 2) occupied by a single shop unit. The upper floors are multi-tenanted offices. The detection system will be an L1 system (not installed yet but soon will be).
My problem is until recently a secondary means of escape was available via a roof and through a neighbouring property however this route is no longer available. There is no other secondary route available. Installing two door separation to the single staircase makes the building non viable due to the loss of lettable space.
What are my options?
I have considered pressurisation of the single staircase and upgrading of the doors but these create their own problems.
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Sounds like a small unit but even so its pushing the boundaries too far.
Does the single stair continue to basement? Does it discharge to a final exit?
The office accommodation sounds untenable to me, and even for the shop to continue the doors need upgrading - would they meet the English Heritage spec for upgrade ( 35mmstiles, 6mm panels?)
A combination of sprinklers, ventilation to the stair, full AFD and upgrade all doors may be a solution but needs agreeing with local friendly fire safety Officer. If he sees it as it is it is more than likely to result in a prohibition.
There a lot of buildings like this about, the brigades tend to not go looking for them but will act when they do come across them.
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Does the building have timber floors and stairs?
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I would look at why the original secondary MOE is no longer available. Check to see if there is a ' deed of easement'. If there is then this must be opoened up again. Even if it enters another property.
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I worked on a project similar to this scenario about 12 months ago. The only way we could get acceptance was to have installed a high pressure water mist system. This was done and the building was accepted. Originally a sprinkler system was asked for but it would have been an absolute nightmare to have installed so the high pressure water mist system was proposed as the maximum pipe size was only 18mm! I can point you in the right direction for these systems if you wish? Just e-mail me?
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I worked on a project similar to this scenario about 12 months ago. The only way we could get acceptance was to have installed a high pressure water mist system. This was done and the building was accepted. Originally a sprinkler system was asked for but it would have been an absolute nightmare to have installed so the high pressure water mist system was proposed as the maximum pipe size was only 18mm! I can point you in the right direction for these systems if you wish? Just e-mail me?
Ashley,
Would you be willing to give us some detail about the specification of a water mist system for such purposes. i.e. what standards was it installed to, what areas were protected, what circumstances lead to the system activating, what duration is the mist supplied for, what is the maximum size of fire it can deal with? Was it easy to get FRS and insurer approval for the system? Are you as confidennt in the systems robustness as an approved sprinkler system?
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Thanks for the responses so far.
Kurnal, the stairs do not continue to basement but discharge direct to open air. I'm not sure if the doors meet English Heritage spec for upgrade, this is one of the problems I was referring to about upgrading of the doors. It is certainly one of the options I am looking at.
Chris, the stairs and floors are of timber construction.
PSmith, the issue of secondary means of escape has been totally exhausted and is just not an option although it is the one that would be most satisfactory.
Ashley I am interested in your proposal for a water mist system but I think Chris raises a lot of valid questions. I would be interested to hear a bit more.
Regards, Shaun
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Shaun
A good interesting project no doubt.
I would make the following observations:
WITHOUT INTIMATE DETAILS OF THIS BUILDING, I ONLY MAKE COMMENTS OF A GENERAL NATURE.
Special problems of historic buildings.
Firstly ..the construction and form of historic buildings frequently incorporate features which may assist in the rapid development and spread of fire. For example, exposed timber floors, walls lined internally with combustible materials, continuous voids behind panelling and undivided roof spaces.. to name but a few.
Secondly... the impact the measures need to provide satisfactory means of escape, have on the sensitive architecture and historic settings.
From your brief narrative, it is clear the means of escape may be unsatisfactory, and from the existing use as shop and office accommodation it would appear that there is the potential for significant numbers resorting to the premises.
Your first step should be to consult with BS 5588 Parts 3,4 & 11 and take your guidance from these documents. I would not consider the use of water protection in any form and I suspect neither would English Heritage. I also confirm that pressureisation of the staircase may be your answer along with addition protection to the doors leading off such a staircase... however it would seem to me that as a minimum 2 door protection to the single staircase is essential.... Is it not possible to upgrade the doors using Intumestscent treatments... also check out BS 8214......and the relevent TRADA documentation on Fire Resisting Doorsets by Upgrading. Hope this helps.... but if you need any further assistace contact me via my email address.
Regards
Conqueror.
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Conqueror
What have sprinkler systems done to offend you?
I dont think English Heritage would have a problem with them- especially since the Windsor fire. They have been fitted in much of Chatsworth House with great success.
They make an active contribution to both life safety and heritage by attacking the fire in its early stages.
Passive measures will do nothing to protect the fabric of the building and a lobby approach will surely detract from its character?
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I would not consider the use of water protection in any form and I suspect neither would English Heritage.
Can I just say, if you are suggesting that water and historical buildings don't mix, the fire and rescuse services won't hesitate applying a lot of it (indeed a lot more than a sprinkler system will) should a fire occur. The insignificant amount of damage that a sprinkler system may do is a drop in the ocean compared with the fire damage and the water damage from a fire fighters hose.
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I'd also like to add that I was not implying that a water mist system was inferior to the sprinkler system, I was just asking some questions to learn more.
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Just reading this with interest........
My question is how are the premises remaining in use when there is a single staircase situation and 8 floors?
Surely there is a slight exceeding of travel distances here?
I note there is no AFD, so is there an interim measure in place to give warning in the event of fire until such time the alarm is installed/commissioned?
I have to say, and this is my opinion, that if I was made aware of this premises, I would seriously consider a section 10, or as a minimum, restrictions on the use of most of the upper floors. This decision would be based on the risk to life of persons resorting to the premises, its use, the single direction of travel and distance and lack of fire detection.
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Chris, you are right to be cautious. There is currently no BS or European Standard for water mist systems.
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Hi Ian
you are right about the lack of standards at the moment- though these systems are widely used in ships and there are some very rigorous IMO standards, and many of the tests replicate occupied rooms.
I think if its good enough for a ship where lets face it you are out there miles away from any help and with little chance for escape then it must be worthy of consideration on terra firma. The problem is as always breaking into an existing market with a new approach. The politics and in my opinion some of the vested interests of the sprinkler industry have so far held the technology back, though some of the big names are now starting to move things forward. And it can be used on difficult fires - switchrooms, engine rooms etc.
The standards will lag some way behind the market - and therefore it will take some brave decisions to move it forward.
That being said, the rather extreme situation under review may call for the surety of an unlimited water supply if at all possible.
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Firstly, let me give a little back ground as to the project I was involved in. It may or may not fit this scenario but it is worthy of some debate and consideration.
The project involved a large listed building in the historic heart of Edinburgh. I do not wish to mention the client other than to say it was a major Scottish bank and this was its head quarters building.
The problem was that the building was a rambling building with many floors and mezzanines that had been added over the years, as result the means of escape had become a bit of a shambles. Whilst there were other escape stairs, these were not accessible to a large % of the staff within the building (including the board of directors)! The only escape route for the people within this part of the building was down a single stairs, down four floors (or up if you were in the basement) and out into a large reception lobby. A lot of the office areas off the stairway had no doors let alone fire rated doors! The inspecting authority were rightly concerned by this and insisted that as part of the building refurbishment a solution must be found. They wanted the stair way to be enclosed, but this would have upset the conservationists and the architect. In the end the solution that was agreed was to fit fire doors to all offices and corridors opening onto the escape stairs and to protect the escape stairs with a high pressure water mist system. The system selected was Fogtec but there are others that would have been acceptable for the task. I advised that the system should be controlled by smoke detectors rather than by heat activated glass bulbs, but this was not taken up. There were several reasons why the fire authorities accepted this solution.
1) The ability for the system to remove a large quantity of large smoke particles i. e smoke washing and to keep the escape stairs free of smoke.
2) The rapid temperature reduction that you see when these systems operate.
3) The ability to suppress and control, and in some instances extinguish a fire within the large lobby area.
In general it was seen by the fire service as an escape stair protection solution and to extend survivability to escapees.
From an engineering point of view there were many reasons for this system to be chosen, including;
a) Low water consumption compared to a sprinkler system.
b) Smaller water storage capacity required.
c) Small bore stainless steel pipework.
d) Ease of installation within an architecturally sensitive building.
The final solution was a pump system producing 120 lpm at 100bar pressure, wet pipe, fast acting bulb actuated nozzles and a 1000 ltr break tank toped up from the towns mains via a 45mm feed pipe at 6bar. Each nozzle produced 12 lpm of water mist with droplet sizes of between 60-100 micron, the K-Factor was 1.2
Now, moving onto the questions concerning approvals. There is NO BS for these systems, there is no LPCB approval for these systems. The reason for this is that the LPCB do not have a test written for HPWM systems and the BS do not have any interest! However, there are approvals available but all a risk specific i.e FM, VdS, IMO, Lloyds. Primarily these systems grew up in the shipping and offshore business and as mentioned before, the testing requirements for these applications are very stringent. From these tests organisations such as Factory Mutual (FM) developed there test standards and approvals. For example IMO A800 which covers all accommodation & public areas on board a ship is the basis of the FM light and ordinary hazard approvals.
I have worked with these types of systems now for many years and can say that they are not a 'one size fits all' solution. For example any deep seated fire would not be controlled by a high pressure water mist system in the traditional sense, but install a detection system to activate the system rather than using glass bulbs, and the system works very well indeed. These systems are not new, in there present form they have been available since 1990, but infact were around 100 yrs ago!
The sprinkler companies are concerned that there traditional market may be at threat and as such often mislead people regarding what these systems can and cannot do. However, they have seen the writing on the wall and are them selves now offering HPWM systems. If you were to compare a sprinkler and a HPWM system on price, lets say for a supermarket, sprinklers would be in the region of 25% cheaper. This is due to the fact that HPWM systems use 316 stainless steel!
For cases where it is not practical to install sprinklers due to water supply problems, space restrictions, architectural constraints etc, these systems are worth a look at. A word of caution, and this is where an LPCB accreditation would be useful (but one does not exists), whilst some companies profess to being 'water mist specialists' this is often not the case. This is even the case for the large fire protection companies. My experience is that there are one or two very good small companies out there that specialise in these systems and often do the installation work, etc. for the big boys!
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Thanks for the detail ashly - where were the heads located?
Throughout the building?
in the accomodation off the stair?
or
Just in the stairway?
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The heads were located in the stairs, landings and the lobby.
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Kurnal, I hope you didn't read my post as a negative view of water mist systems. I think they can be very useful and have recommended them myself. However, I merely suggest that one ought to be cautious when someone might accept a system (designed to who knows what) to compensate for quite extreme lapses in traditional protection. Few of us can be so familiar with the technology and testing (which is limited as you say to ship's cabins etc).
Also, from what I know of these systems, I would question the assertion that they are cheaper. If they are to provide partial protection and limited operation times - OK they will be cheaper. But I cannot see how they are cost effective if we ask them to do the same as a fire sprinklers designed to BS 9251 or 5306 or BS EN 12845.
Incidentally, guidance is being prepared by BRE on this very topic. However, we really do need a DD which the water mist industry are trying to produce.
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In these days of non-prescriptive solutions to major building difficulties and the thought process of risk reduction and prevention, the provision of sufficient staff training to respond to an L1 system is sufficient. Whilst the shop process will allow people to resort to these premises, sufficient staff training will allow escape on early detection. Surely we are not suggesting that a fire will grow to sufficient proportions to stop escape. All doors are fire doors, rated to such or not and even those that are rated may not be satisfactory once put in position without the frame and screen they were tested with.
I recenetly visited Rome, a european country subject to that nice piece of legislation which gave us the Workplace Fire Precautions Legislation, and stayed in a lovely hotel. The fact that it had a 4 metre ceiling height, was 8 storeys with a basement, had a basement kitchen open to the single staircase with no doors to the staircase, the bedroom doors had vents in them, smoking was allowed within all areas with nice sand trays by the lift, not in a lobby, for the disposal of cigarette ends, had flaked canvas hose in a box for use if needed and as a by the by the staircase did not discharge to open air. No problems for our Italian colleagues, so perhaps the earlier discussions may be considered a burden to business and ever so slightly over the top.
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Jokar
you should be an estate agent- your talents are wasted in the fire industry!
We used to have a few hotels and workplaces that sound a little like that too. Like you I also remember the good old days when it was ok to lose a few folk in fires- it set an example and kept everyone else on their toes.
You are right on the influence of europe though, the level playing field envisaged by the treaty of Rome has never materialised.
Ian- of course I never doubted where you would be coming from but seemed a good opportunity to air an issue that keeps getting buried for some reason. Its a typical chicken and egg situation but in this case the farmer keeps coming and selling the egg and eating the chicken for lunch so we never seem to get anywhere.
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Ah, the days of paraffin heaters and open fires and loss of life in commercial premises. What is it, I know 3 people died in commercial premises in 2003 out of 593 in total. Thats the problem with the fire industry, it is an industry, risk reduction and prevention do not enter the equation when money earning money is a concern. Ask the individual if they have had a fire, how large it grew to be and how it was extingusihed. Then add was anyone affected by it and you may have a scenario to deal with. Double guessing against guidance documents which are exactly that or recommendations in British Standards, industry led of course, isn't an exact science. We all want everyone to be safe from fire and the risks from fire but how does the answers to the first question raised achive that at a reasonable cost to the business person. For that type of outlay what is the return, especially from an existing building that may never have experienced a fire situation.
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Another viewpoint of course, is to have the building fitted with an oxyreduct system. No fires are able to start and the atmoshere is breatheable to all, although some vunerable people may not like the experience.
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Is there not a time limit that a person can be exposed to the oxyreduct system? Please tel us more?
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Ashley can I applaud your solution and beliefs from here in Edinburgh (where your description of the premises fits a certain building very well).
I too have used the IMO tests and specifications along with NFPA 750 (2003) to specify a HPWMP system forming part of the fire engineered solution for a life safety provision. I remember well (and still receive) the absolute rejection of the systems from more traditional colleagues. However, after much debate the sytem has been accepted by our Enforcing Authority and our Building Standards Agency as an acceptable solution.
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You might be interested to know that the European Commission have just set up a task group to look at the problem of fires in hotels that are causing: loss of life, injury and economic loss on mainland Europe. Maybe Jokar's hotel isn't going to be quite the same soon?
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There has been a voluntary european standard for hotels for years. Nobody ever took any notice of it.
The UK already does all that this code says other than prohibiting mirrors in corridors.
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Ashley the heads are in the wrong place!!!
There is no point spraying mist into smoke that has come from a fire in and adjacent room. All you will get is wet.
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You are correct on both of your last 2 posts wee B.
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Brian
You echo my initial reaction to Ashleys scenario. But then on reflection it appears that the staircase is a large area probably containing fire risk - and not a protected route. So the provision of fire doors to rooms will provide passive protection and limit the effect of a fire in a room, coupled with the L1 system giving early warning of fire. The mist system would be to cover the an incident in the staircase itself- creating some potential for the control of an incident and hopefully maintaining tenability within the stair. From this point of view it looks quite an imaginative and creative solution to a difficult problem subject to Ashleys caveats over the choice of detection!
Of course a full coverage system would be much better still but I guess the owners could not run to it, bankers usually struggle to make a living don't they?
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Why not an L1 radio fire alarm as a compensatory factor, saving a lot of cabling, pipework and grief from Heritage ?
Another viewpoint of course, is to have the building fitted with an oxyreduct system. No fires are able to start and the atmoshere is breatheable to all, although some vunerable people may not like the experience.
OxyReduct reduces oxygen levels to below 16%.
You would need to do a very comprehensive risk assessment, and carry out a health check on everyone entering the area to check for respiratory and heart problems.
The area would also be classified as a confined space.
This doesn't sound to me like a suitable application....
Jokar, are you the rep I met recently at Sandown?? =D
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Ashley,
4 hours in and a 30 minute break, ok for workers perhaps but not for shoppers. Those with health problems may not be allowed to enter such a system.
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Jokar
I assume that Oxy reduct needs a reasonably leek free enclosure to work.
Kurnal - I see your point.
Ian G - agreeing with me Ian - whatever next.
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Ashley the heads are in the wrong place!!!
There is no point spraying mist into smoke that has come from a fire in and adjacent room. All you will get is wet.
Remember that an added bonus with High pressure water mist systems is the 'smoke washing' capability. This is briefly what happens, the large smoke particulate is absorbed by the finer water mist droplet and this makes the droplet heavy. It then drops to the floor and on a large scale, creates a survivable condition within the area that is becoming smoke logged. It also reduces temperature within the stairwell dramatically. The only down side with the actual project is that the smoke washing effect only comes into effect when the heat has activated the glass bulb, hence my earlier comment about open nozzles being best.
I agree that total coverage within rooms and escape routes would be the very best scenario.
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Ashley
Ive heard tell of this "smoke scrubbing" effect before. Sprinklers are supposed to do it as well. (with droplets larger than the smoke particles).
I am not sure there is any evidence of the mechanism you describe just that there appears to be a reduction in some of the nasties that have been measured in experiments. I am not sure there are any data available for fires occuring outside the protected area.
If there is any info on this I'd be interested to see it.
As you say the thermal actuation of the mist system would be serious draw back if you were relying on it to "scrub" smoke entering the stair enclosure from adjacent accomodation. Open heads and AFD operation is better but liable to unwanted activations.
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Wee Brian,
I believe you may be right regarding test data availability for smoke scrubbing in an area outside the fire effected area. I will look into this. You mention sprinklers having an ability to do the same as water mist. This is true but the droplet size compared to a high pressure mist (HPWM) droplet is huge i.e 1000 micron compared to 60-100 micron for HPWM. What this means is that the free fall velocity of the sprinkler droplet is greater than that of the HPWM. In other words the HPWM floats in the air absorbing 'sooty' particles until it gets to heavy.
It is true to say that none of these systems are able to reduce smoke in its entirety, it tends to be only the visible particulate, nonetheless, very impressive when you see it work and breath the results without BA.
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And in addition to the slower free fall velocity the surface area of water is infinitely larger, so therefore should be much more effective. But how much is the question. I have seen manufacturers claims and some test data but I have never seen any independent accredited test results.
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There were some tests done by a guy called 'Jack Mawiney' of Hughes associates in the USA. I am trying to get more information.