FireNet Community
FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Safety => Topic started by: Tom Sutton on February 15, 2010, 07:49:11 PM
-
I seem to be in the middle of a little difference of opinion between a couple of fire professionals. I have had a fire risk assessment carried out at our property in November (by an ex-brigade officer). The FRS carried out a site visit at the end of January and has decided the risk assessment is inadequate. I can work my way through most of the bits and assist the FRS by complying with some of their requests for additional detection and intumescent seals however they are requesting that we fit these seals on every bedroom door. The fire risk assessor in reply to this request has pointed out that the room doors are of substantial construction, in good condition and fit well. Given the level of smoke detection on either side of these doors a realistic view would be that the seals wouldn’t operate because such substantial doors would require an extensive fire to take the seals to a situation where they would expand.
This is an enquiry I receive quite often FRS requiring intumescent seals fitting on fire doors that have been is existence for quite a long time, and contrary to the Fire Risk Assessors views, any observations.
It’s a Scottish Hotel 138 rooms I am also waiting for more information.
-
IMHO if the fire doors are to BS 476 part 8 and as stated fit well in the frame then they should be suitable. No one has ever, to my knowledge, stated that a door that started out tested to BS 476 part 8 and then been cut about or otherwise to fit strips and seals retains its certification to that standard. The latest standard BS 476 part 22 and 31 require strips and seals for the door in its tested door set. However, Auntie Lin in the past has anwered some of these queries and a search of the site may well find her answers.
-
I have had the same problems myself where a FRS officer has come along and said the same thing and also ask for the fire alarm system to made L1 standard. I have contested the comments stating that I have risk assessed the premises and not taken the easy route of just applying best practice. Surely the FRS job is to undertake an audit and not simply apply 'new build' type of standards.
The RRFSO was not intended to be a tool to upgrade every premises to the best standards but to have an organised look at things and make reasonable recommendations. Could it be that, in some cases, civilians are now undertaking these audits who are not trained at seeing the bigger picture and how one thing can affect other things in a fire risk assessment. If it was just about applying best practices we could do a fire risk assessment over the flippin' phone by just asking a few questions. Sorry, do I sound grumpy or have others experience similar frustrations
-
Search all of Auntie Lin's posts. She has berated me before on this subject but she is an expert.
-
I'd advise you to contact the officer and ask for clarification - requirement or recommendation?
As an inspecting officer, doors which do not have strips and seals are recommended to be upgraded, but that is based on an inspection of a sample of doors to ascertain their condition, fit and whether they are subject to routine inspection by the responsible person. The recommendation is not enforceable, but I do explain that it will increase the standards in the premises and that it can be carried out on a rolling program if needed supported by the risk assessment and an action plan.
As Jokar states, the doors are tested with strips and seals as a complete doorset ... frame, fixings and furnishings to be certificated.
-
TW
Are smoke seals fitted?
The fact that smoke rather than heat is fitted, to me means that the standard is far higher than most hotels.
Another factor to consider is management. Staffing levels, practised procedures, servicing etc.
Also time for brigade to respond perhaps, if in the highlands it might be in the hotel's best interests
davo
-
Thanks guys I have asked for more info and I am not directly involved in this case just been asked a question.
-
Fire doors have to be capable of withstanding the passage of smoke at ambient temperatures. If the door does not fit neat enough to prevent the passage of smoke then seals may need to be fitted.
Despite what some think the fitting of smoke seals to a door does not necessarily mean the passage of smoke will be prevented. I have seen doors with smoke seals fitted where a strip of chewing gum would have been as good.
Nowadays when a door is tested everything is thrown at it to ensure that it passes and gets certified. I have no doubt that had the joiner inadvertantly left his plastic duck on top of the door and it passed the test we would then be requiring the provision of like plastic ducks on doors as well.
We are so hung up on requiring smoke seals to be fitted to doors rather than requiring the door to be smoke stopped.
-
The RRFSO was not intended to be a tool to upgrade every premises to the best standards but to have an organised look at things and make reasonable recommendations. Could it be that, in some cases, civilians are now undertaking these audits who are not trained at seeing the bigger picture and how one thing can affect other things in a fire risk assessment. If it was just about applying best practices we could do a fire risk assessment over the flippin' phone by just asking a few questions. Sorry, do I sound grumpy or have others experience similar frustrations
Paul2886 - I have also experienced (as many others) a difference in opinion with the FRS when it came to the necessary fire precautions of buildings not to current regs. As you state I do not believe it is always necessary to bring an older building to the requirements of new building standards; however, many FRS are prescriptively applying the HMSO guides so in effect are. Maybe much of our trouble is that we now live in a letigious society that would seek to presecute the FRS if they did not insist on the best measures available and also we live in a time when (dare I say it) not 1 life is expendable and therefore a FRA has to be so good to ensure this level of perfection is maintained. The cost / benefit in applying all these regs and measures is arguably not balanced. Easy for me to say until someone I care about is affected then of course off down the solicitors I'd go!!!
-
As it is a Scottish Hotel go to the Practical Fire Safety Guidance for Medium and Large Premises Providing Sleeping
Accommodation
Go To Technical Annexe 13.9 where it states:
Bedroom Corridor Doors
6. Where a bedroom opens into a circulation area, a fire occurring in the bedroom or
other room opening into the circulation area will pose a threat to the occupants of other
rooms who have to use this circulation area for potential escape.
7. The provision of fire-resisting doors offers protection to the escape route from a fire starting in a bedroom or other room. More modern premises may have FD 30S doors fittedto the bedrooms in compliance with Building Regulations. In other cases existing doors may be suitable which, while not meeting the specification for an FD 30S door, are of substantial construction and close fitting. Some doors may have the potential to be upgraded to nominal
FD 30S standard.
Simple really. ;)
-
The doors seem to range in age from 1997 back to1980s. The rebates are mainly 25mm x 45mm.
In the past when intumescent strips were installed on doors with 25mm rebates the opinion then was the 25mm door stop inhibited the actuation of the strips and 12mm door stops should be used. Using this argument the 25mm stop was doing its job without the intumescent strip so why is it needed now.
If it’s a well fitting door and regularly maintained then the amount of smoke that would pass would be minimal so again are smoke seals required, especially with an L1 system installed.
Fire Doors with inch rebates and no smoke seals were the norm in the seventies and still provide an adequate level of protection today, certainly this is some people’s opinion.
http://www.kingfell.com/~forum/index.php?topic=4073.0
I accept in new build or refurbishment the latest standards should be applied (certificated door sets or assemblies) but in existing situations were the fire doors are of a good standard should they not be accepted?
-
Having specialised in fire doors (amongst other things) in a previous life, and having seen loads of fire resistance tests on timber doorsets, both to BS 476: Part 8: 1972 and Part 22: 1987, my observations are as follows:
• Door stop size does not make a significant difference to the fire resistance rating of a timber doorset;
• Door stop size does not make any difference to the smoke sealing ability of a timber doorset (TRADA did some research that demonstrated this, I seem to recall);
• People who say that because a door passed a test that was superseded nearly 30 years ago it is automatically still OK are (in my view) missing the fact that the benchmark of acceptability as regards safety performance changes over the years, and when assessing safety one has to refer to current good practice – not 30-year-old good practice. If (as is stated) some of these were installed in 1997 they fell well short of the good practice benchmark that was a requirement of that time;
• When a doorset is described as being ’30 minutes’ fire-resisting that does not mean it will last 30 mins in a fire – it might last longer or it might fail more quickly. The Fire resistance tests are a ranking methodology, used as such in the guidance to the Building Regulations, not a means of determining ultimate fire performance;
The above does not mean that I consider that every existing fire door should be upgraded to the current standard. It means, though, that those undertaking the risk assessment need to understand that doors that aren’t up to current standards would not provide the current ‘benchmark’ level of fire separation and/or smoke sealing performance. They then need to assess whether that is acceptable;
My experience tends to be that you can tolerate a certain degree of flexibility in fire resistance performance (say, accepting 20 mins where the AD-B would require 30, if there are no hazards that are ‘unusual’), and there’s plenty of advice available regarding how to judge the fire resistance of existing timber doorsets (and upgrade if necessary), but that it’s more often than not smoke sealing that is critical. If you need smoke sealing then the only way you will get that achieved effectively is by having correctly installed, well-fitting doors that incorporate cold smoke seals. Having a big stop on a door frame will make little difference to smoke sealing performance. If you therefore conclude that you need to fit smoke seals, in most cases you may as well fit combined intumescent/smoke seals, which give you the benefit of improved fire performance at next to no additional cost.
Finally, there was, of course, the determination (http://www.communities.gov.uk/documents/fire/pdf/heritagehotel.pdf) that dealt with this issue and had as one of its conclusions “It is considered that the existing doors (even with self closing devices fitted) cannot be relied upon to prevent the egress of smoke at the early stages of a fire”. As the Determination states, this only applies to the case in question and in consideration of the particular risks found in that premises, but whether or not one likes or agrees with the conclusion of the determination, it’s now in the public arena and we have a responsibility to consider the ‘good practice’ benchmark that it provides when we’re making our safety decisions.
In summary, I think that the benefits of upgrading the fire and particularly the smoke resistance performance of doorsets is often dismissed too lightly. It’s not that difficult to achieve and in certain cases, to protect certain risks, it can be hard to conceive how a case can be made for not achieving a certain minimum level of fire and smoke sealing performance.
-
Playing devil's advocate here, would you not agree intumescent strips are really for property protection, rather than life safety (other than in premises where there is a stay put policy)
Surely if (and I realise this can be a big if) everything else is in place , ie; appropriate early warning, good management, smoke seals on fire doors etc etc people should be long out of the building before conditions have deteriorated to the point intumescents will activate.
How many of you can hand on heart say they have been to post fire scenes and have found fire doors where the intumescent strip has activated on a regular basis. Ive been to my fair share of fires / post fire scenes and can count on one hand the times ive seen that happen.
Discuss!
-
Door stop size does not make a significant difference to the fire resistance rating of a timber doorset
I would agree if the doorset was fitted with intumescent strip and the 12mm stop would most probably more effective. But to make these comparisons you would have to see the doorsets tested without intumescent strips was this the case?
If so you must be an old git like me. ;)
Door stop size does not make any difference to the smoke sealing ability of a timber doorset (TRADA did some research that demonstrated this, I seem to recall)
I would be very interested in this research do you have any further details? I would like to know the amount of leakage to determine the threat to a means of escape?
-
Playing devil's advocate here, would you not agree intumescent strips are really for property protection, rather than life safety (other than in premises where there is a stay put policy)
IMHO Property protection. Intumescent strips date back from the ark and were important in the days before AFD. They cant be for life safety save for places with stay put policy as youve already said.
-
Intumescent strips date back from the ark and were important in the days before AFD.
Not true Cleveland they arrived on the scene in the late seventies and at that time most certificated hotels was being fitted with AFD. But I will accept AFD was not as trusted as it is today and passive protection was preferred.
-
Regardless of the function they will perform, the strips & seals are simply there because a door would not pass the BS 476 test without them since a door can fail the test on the amount leakage. I believe that this was indeed a new requirement in the later 1970's, and I think Kurnal knows the proper BS where it all changed.
-
Quite. But you would perhaps agree Civvy that when looking at existing fire doors it is overburdensome to insist that the doors be upgraded with intumescent strips. They do little to increase life safety (again unless we are dealing with buildings with stay put policies)
-
In the majority of cases yes, it would be unnecessary. Each case on its own merits though.
-
Interesting.
I have visited many, many office buildings that have had major interior refurbishment 20 odd years ago in London over the years, in regards to Safety,Construction and Fire dealing with Property agents.
I must admit most cases existing fire doors have not been upgraded, and will never be for the main reason of cost. I may also add where inspecting fire officers have visited such properties this has not been an issue.
Maybe in the ideal World all existing fire doors would have these kind of upgrades, but not where I am sitting.
-
This old thread may be of interest
http://www.kingfell.com/~forum/index.php?topic=3292.0
-
I hope I am not trying to teach my grandmother to suck eggs, if I am I apologize but the history may clarify some points.
Strips and seals developed separately and you have to consider them that way. Initially to pass a BS 476 part 8: 1972 test the doors were made of expensive hard wood filled with a FR material and 25mm stops. Fire door manufacturers looked for cheaper ways to produce them and the answer was intumescent strips which took quite a long time to develop also it was found 25mm doors stops were not necessary. By early 1980 fire door using intumescent strips was the norm and in 1987 a higher standard BS 476 Part 22 :1987 was introduced which was a targeted at fire doors and it was argued the old part 8 doors would fail the new standard at least the ones without intumescent strips. This remains in force today together with the European standard BS EN 1634-1: 2000.
In the seventies cold smoke seals were used on cross corridor fire doors to control any cold smoke in corridors and there was no BS test. We called them smoke stop doors and were usually 20mins FRSC doors fitted with cold smoke seals. BS 476-31.1 was introduced in 1983 which was the test for cold smoke seals. At some later date it was decided to control cold smoke in the room of origin and the designation FD30S appeared.
-
Hello chaps - see you're taking my name in vain again! (Should spend less time working and more on FireNet I guess!).
Can I pick up on some of the things you've talked about? (Here's Auntie Lin's potted lecture for the day)
BS476: Part 8: 1972. This standard developed because of research (Fire Research Station I think) which showed that when fire developed, the pressure in the fire compartment increased, and smoke and hot gases looked for more space to move into. This led to the development of a positive pressure fire test (Pt 8) and developments such as fire seals. To be a Pt 8 door for anything more than 20 mins, it would have had to be tested with a fire seal fitted and therefore, in use would have needed the seal fitted in order to comply with its certification.
Paul2886 - interested in your comments about 'civilians and FRAs over the phone. Had a very interesting chat yesterday with a lady who had been bullied by her local fire brigade into buying into something called FireSmart. Anyone know anything about these people?
Davo - as it's a hotel we're talking about, shouldn't we consider the likely capabilities of the room occupants to respond to a fire (no - silly boys - not THAT sort of capabilities - whether they've sampled too many of the malts in the bar!)
Nearlythere - fit of the doorset is everything. A well-fitting door (even gaps, not exceeding 3mm) may provide a reasonable level of protection, but I've done many surveys over the years and have yet to go to a building where all the doors are cared for to this level of fit.
Fishy - have to agree about the uselessness of 25mm stops. The only thing they're really good for is allowing an incompetent chippy to throw the leaf into the frame and get paid and off site before anyone notices. I was appalled a number of years ago when lecturing at FSC when one of my students calmly told me he always asked for 25mm stops "because otherwise the door won't touch the frame".
MidlandLion - what's wrong with property protection if you're a responsible building owner and employer? Can't lay hands on the stats. like you guys, but I know that a significant proportion of businesses which have been involved in a fire never recover, and that's good enough reason for me.
TWS - just hi from one old git to another! Yes, I've been round the block a few times and have seen both negative and positive pressure tests on fire doors.
Martin672 - do you want to contact me about surveys on doors?
There you are chaps - that should keep you all going for another ten minutes or so. Auntie Lin is available to lecture at parties, bar-mitzvahs and working mens' clubs!
-
MidlandLion - what's wrong with property protection if you're a responsible building owner and employer? Can't lay hands on the stats. like you guys, but I know that a significant proportion of businesses which have been involved in a fire never recover, and that's good enough reason for me.
Hiya Auntie Lin - always good to see you - you must pop in more often !!!
I certainly dont disagree with you, and yes building protection is an important consideration, I was debating the point however that intumescent strips aren't provided generally for life safety reasons (except buildings with defend in place strategies)
-
BS476: Part 8: 1972. This standard developed because of research (Fire Research Station I think) which showed that when fire developed, the pressure in the fire compartment increased, and smoke and hot gases looked for more space to move into. This led to the development of a positive pressure fire test (Pt 8) and developments such as fire seals. To be a Pt 8 door for anything more than 20 mins, it would have had to be tested with a fire seal fitted and therefore, in use would have needed the seal fitted in order to comply with its certification.
Between 1974 and 1979 I specified many half hour fire doors none I recall with intumescent seals and I also accept most were nominal fire doors (upgraded fire doors) and many will have been replaced because of the material used. However there will be many still in use today because this was the norm at that period. If it is considered that these doors are not fit for purpose then I need to see examples that these doors have failed and were considered a contributory factor in the death of some person. Incidentally property protection was never considered and that was left to the building regs.
If you was conducting a fire door survey and came across substantial well fittings doors with inch rebates with no heat seals would you insist they be fitted?
-
Hi Tom
Intumescent strips aren't a life safety provision. They are fine for property protection or places with stay put policies, but otherwise if I came across most buildings and intumescent strips weren't fitted on any of their fire doors I'd simply recommend that when the doors are due for replacement any new doors should be fitted with the intumescent strips (and all the other bits and pieces, such cold smoke seals etc etc).
I certainly wouldn't be specifying on a deficiency letter that the doors must be upgraded with intumescent strips immediately or within three, six or twelve months for instance.
So whilst previous standards mentioned that one inch rebates meant you get away without fitting intumescent strips I would argue that if you came across a fire door with smaller rebates without intumescent strips you wouldnt deem it to be a huge problem that could possibly endanger lives.
-
Hi Tom
Intumescent strips aren't a life safety provision. They are fine for property protection or places with stay put policies, but otherwise if I came across most buildings and intumescent strips weren't fitted on any of their fire doors I'd simply recommend that when the doors are due for replacement any new doors should be fitted with the intumescent strips (and all the other bits and pieces, such cold smoke seals etc etc).
I certainly wouldn't be specifying on a deficiency letter that the doors must be upgraded with intumescent strips immediately or within three, six or twelve months for instance.
So whilst previous standards mentioned that one inch rebates meant you get away without fitting intumescent strips I would argue that if you came across a fire door with smaller rebates without intumescent strips you wouldnt deem it to be a huge problem that could possibly endanger lives.
You're obviously a critter with loads of common sense Midland Whoeveryouarenow. Unfortunately, and despite it's name, commonsense is not that common and you are most likely in the very high minority.
I have seen a report of a prosecution in this forum where someone was pinged for not having smoke strips on doors. Not, I might add, for failing to have fire doors which would be capable of resisting the passage of smoke ay ambient temperatures.
Two different things in my view. One is because most book says so, and the other to provide smoke stopping capabilities.
-
I know that for doors with strips and seals 3mm +/- 1mm is considered will fitting but is 3mm still considered well fitting for a door without strips and seals but with the larger rebate?
Another question, why 3mm? Because it is reasonable to expect that an adequately made and regularly used doorset can achieve this and to expect a tighter fit would be unreasonable? I suppose the curved path taken by the leading edge as the door rotates also prevents a tight fit. Or because it stops the larger smoke particles getting through? ;D
-
Door stop size does not make a significant difference to the fire resistance rating of a timber doorset
I would agree if the doorset was fitted with intumescent strip and the 12mm stop would most probably more effective. But to make these comparisons you would have to see the doorsets tested without intumescent strips was this the case?
If so you must be an old git like me. ;)
Door stop size does not make any difference to the smoke sealing ability of a timber doorset (TRADA did some research that demonstrated this, I seem to recall)
I would be very interested in this research do you have any further details? I would like to know the amount of leakage to determine the threat to a means of escape?
Yes - not an old git, but a git nonetheless. Seen them tested without the intumescent strips & they do around 15 mins, depending upon construction & fitting. You can intuitively conceive that the size of the door stop will make no significant difference if the fire is on the opening side of the door, and this is borne out by 'real' tests.
Playing devil's advocate here, would you not agree intumescent strips are really for property protection, rather than life safety (other than in premises where there is a stay put policy)
Disagree, I'm afraid. The only reason that we have them is that they are required so that timber doorsets meet the fire resistance performance referred to in the National guidance to the Building Regulations (e.g. the ADB in England & Wales). These Regulations have nothing to do with property protection - only life safety.
-
MidlandLion - what's wrong with property protection if you're a responsible building owner and employer? Can't lay hands on the stats. like you guys, but I know that a significant proportion of businesses which have been involved in a fire never recover, and that's good enough reason for me.
Hiya Auntie Lin - always good to see you - you must pop in more often !!!
I certainly dont disagree with you, and yes building protection is an important consideration, I was debating the point however that intumescent strips aren't provided generally for life safety reasons (except buildings with defend in place strategies)
I assume that you are assuming that people will evacuate immediately upon hearing an alarm. This may not necessarily be the case though, especially in sleeping risks like hotels.
-
Auntie Lin, Please check your messages.
Bungle
-
Door stop size does not make a significant difference to the fire resistance rating of a timber doorset
I would agree if the doorset was fitted with intumescent strip and the 12mm stop would most probably more effective. But to make these comparisons you would have to see the doorsets tested without intumescent strips was this the case?
If so you must be an old git like me. ;)
Door stop size does not make any difference to the smoke sealing ability of a timber doorset (TRADA did some research that demonstrated this, I seem to recall)
I would be very interested in this research do you have any further details? I would like to know the amount of leakage to determine the threat to a means of escape?
Yes - not an old git, but a git nonetheless. Seen them tested without the intumescent strips & they do around 15 mins, depending upon construction & fitting. You can intuitively conceive that the size of the door stop will make no significant difference if the fire is on the opening side of the door, and this is borne out by 'real' tests.
Playing devil's advocate here, would you not agree intumescent strips are really for property protection, rather than life safety (other than in premises where there is a stay put policy)
Disagree, I'm afraid. The only reason that we have them is that they are required so that timber doorsets meet the fire resistance performance referred to in the National guidance to the Building Regulations (e.g. the ADB in England & Wales). These Regulations have nothing to do with property protection - only life safety.
Fishy.
Check your messages.
-
Playing devil's advocate here, would you not agree intumescent strips are really for property protection, rather than life safety (other than in premises where there is a stay put policy)
Disagree, I'm afraid. The only reason that we have them is that they are required so that timber doorsets meet the fire resistance performance referred to in the National guidance to the Building Regulations (e.g. the ADB in England & Wales). These Regulations have nothing to do with property protection - only life safety.
Oh so that automatically and magically makes them a life safety consideration.Im not sure if your post was made tongue in cheek or not. WHat you summise may apply to new build but what about existing properties? Tell you what why not try enforcing that in a hotel with 60 bedroom doors that need upgrading and see how far you get.
-
Oh so that automatically and magically makes them a life safety consideration.Im not sure if your post was made tongue in cheek or not. WHat you summise may apply to new build but what about existing properties? Tell you what why not try enforcing that in a hotel with 60 bedroom doors that need upgrading and see how far you get.
Well... yes it does. Nothing in the Building Reg's is there to provide property protection per se (admittedly some of the recommendations do relate to fire spread outside the premises of origin). For England & Wales this is spelt out right at the front of the ADB (I quote): "...Building Regulations do not require anything to be done except for the purpose of securing reasonable standards of health and safety for persons in or about buildings (and any others who may be affected by buildings or matters connected with buildings)...". Since the Approved Documents are solely to provide 'good practice' guidance on compliance with those Regulations, it follows that the performance requirements detailed therein relate to life safety only. This isn't my opinion - it's there in black & white.
What I'm saying is that it's an upgrade option that is too easily dismissed - and that the determination that I referred to (http://www.communities.gov.uk/documents/fire/pdf/heritagehotel.pdf) gives you a flavour of how our Regulators view this issue (and bear in mind that this applies to a Grade 1 listed building, where the arguments for leaving the existing doors 'as is' would be stronger than the run-of-the-mill hotel).
-
If that is the determination I am thinking of then they are talking about doors where the hotel owner/employer had admitted that the doors in question would barely last 10 minutes in a fire. That is quite different to asking for an upgrade on an old fire door that just doesn't have the strips & seals.
-
If that is the determination I am thinking of then they are talking about doors where the hotel owner/employer had admitted that the doors in question would barely last 10 minutes in a fire. That is quite different to asking for an upgrade on an old fire door that just doesn't have the strips & seals.
...not sure why - when the "old fire door that just doesn't have the strips & seals" could well do only 15mins in a test, no matter how thick & heavy it is?
In any case I’m not saying upgrade everything; I’m saying that if you don’t have fire-resisting doorsets that comply with current good practice as regards fire and smoke resistance then you need to understand that and assess the consequences. In fire safety (as in other areas of health & safety) acceptability tends to be judged against such good practice, so if you don’t comply you should always be ready to justify why not. If you can’t do that then you have to upgrade your fire precautions – affordability is no excuse not to, under the Law.
As I said in an earlier post, in my opinion compromising on smoke resistance is much harder than compromising on fire resistance. The only way you will get cold smoke resistance to any defined level is to fit seals – stop size, closeness of fit or whatever won’t make any significant difference. If you’re fitting smoke seals you may as well fit combined intumescent/smoke seals. It isn’t necessarily difficult & it isn’t necessarily expensive (you can even get thin surface-mounted seals that can be self-applied by the owner – Google ‘surface mounted intumescent strip’).
As regards the determination – as I said, it gives a ‘flavour’ of how the Regulators view the issue of upgrading timber fire doors. It clearly states that it only applies to the particular circumstances of the case, however If we’re advising our clients with the aim (amongst other things) of satisfying those regulators, it’s an example that we must be mindful of.
-
Hi Fishy
I can't argue with anything you have said, and each scenario has to be assesed on its own merits.
Despite that I still fail to see the life safety benefit of intumescent strips in most situations, even most sleeping risks infact.
I can see the benefit in buildings with stay put policies, or large high rise buildings where it would take a substantial amount of time for people to evacuate.
Perhaps one of the reasons I question the issue of intumescent strips stems from the fact that I can count on one hand the amount of times I've visted a fire scene to find that intumescents strips have activated.
-
I had a further enquiry about FD20 doors and during my research I found an information leaflet from BWF at http://www.bwf.org.uk/fileadmin/documents/assets/FD_2020_20explanation.pdf . Which in my interpretation says a fire doors without intumescent seals can only achieve 20 mins providing it has been fitted to a high standard. A fire door with the same specification and intumescent seals can achieve 30mins consequently if a situation requires 30 mins fire protection then intumescent seals need to be fitted. simples?
-
Tom - you're quite right. It's a myth that a door that achieves FD30 with seals will do 20 without. We did some testing while I was at TRADA (ok - it was last century!) which showed that it was more likely that 17 or 18 minutes would be the common level achieved. In these days of assessing risk, you may consider 17 minutes to be quite adequate, depending on other measures which would offset this reduction but as you point out, the achievement of 20 minutes has to be down to the excellence of fit of the leaf in the frame, and a very stable leaf construction which isn't going to bow like b..... blazes.
-
Auntie Lynn do we know why fire doors fitted with intumescents lasted longer than those fitted without?. Midland Retty got me thinking about how many times ive seen intumescent strips activate. Not many. So im quite confused.Are the tests conducted slightly flawed and unrealistic because unless you have a fire right against the door i cant see how unactivated strips will give better protection.
-
I suspect the reason why you do not see many cases where the intumescent seals have activated is because it is only likely to happen at the seat of the fire or the room of origin where the temperature are high enough and this area is usually damaged beyond recognition after the fire. The rest of the building may be seriously smoke and heat damaged but the temperatures are unlikely to rise high enough to activate the seals.
You must have done a stint in the control tower at Moreton during an exercise on the fire-ground and witnessed the temperatures the can be achieved in the fire houses (1000 degrees F or C ???).
-
Auntie Lynn do we know why fire doors fitted with intumescents lasted longer than those fitted without?. Midland Retty got me thinking about how many times ive seen intumescent strips activate. Not many. So im quite confused.Are the tests conducted slightly flawed and unrealistic because unless you have a fire right against the door i cant see how unactivated strips will give better protection.
Cleveland - the reason why doors with fire seals last longer than those without is simply that fire and smoke seek out the path of least resistance. In the case of a door, it's primarily the gap between the leaf and the frame. When you burn wood, it dries out and shrinks a little bit, and also can deflect. This increases the ease with which fire can pass from one side of the door to the other.....and so on. Don't believe the old myth about the value of a 25mm deep doorstop. If you're looking for something crucial to improve the performance of a doorset, start with gaps which are even around the periphery of the leaf and within the manufacturer's tolerances - and this is usually about 3mm. It's really sad when inspecting officers go round a building and insist on 25mm deep stops when in fact they should have been getting 6-8mm gaps reduced.
The reason you don't see many seals activated in 'real' fire is because so often you chaps get there before the seals can activate. If the door is on the room of origin (and how many of us can say in advance of a fire which one that will be for sure?) you may see activated seals. The seals activate at about 140 deg.C Remember that this is the temperature at the seal -and the seal is set into the leaf/frame junction, so the actual room fire temperature is likely to be 600+ degrees.
If you're interested in knowing about fire testing and seeing how it's done, I think you might find something on the BWF website. If not there was a video produced by West Birmingham Health Authority (last century I know, but the basic principle is the same) which shows a test being carried out. Labs such as Chiltern International Fire and Exova Warringtonfire may well have video clips on their websites. You might also ask a friendly manufacturer if they'll take you along when they next do a test - but you do have to remember that when they are testing it's for the benefit of their business so they might not be very happy about sharing the experience.
-
Cleveland
Adding to Auntie Lin, the IFSA have some factsheets on IS.
http://www.ifsa.org.uk/download.html
Traditionally, the silicate seals activate at about 180 degrees, and as she says, you guys and gals get there damn quick!
The newer carbon seals activate at about 120 and therefore kick off earlier.
If you are serious about upgrading then look at switching types, but do not mix in the same door as this causes deflection as AL has said
davo
-
Auntie Lynn do we know why fire doors fitted with intumescents lasted longer than those fitted without?. Midland Retty got me thinking about how many times ive seen intumescent strips activate. Not many. So im quite confused.Are the tests conducted slightly flawed and unrealistic because unless you have a fire right against the door i cant see how unactivated strips will give better protection.
The tests are not really intended to be 'realistic' - they're meant to be representative. You can't make them realistic unless you duplicate a compartment with the appropriate fire load, ventilation conditions etc, set fire to it & wait for the doorset to fail - this would be impractical, in the vast majority of cases. What the tests do is enable us to rank fire resistance performance in a repeatable & reproduceable way, so we usually use 30 minute construction to separate means of escape, 60 minutes for high-risk areas etc in the knowledge that the construction probably won't do 30 / 60 minutes in a 'real' fire (it might do more or it might do less), but that we're using kit that has the established and recognised 'good practice' performance required for that risk. Our regulators have set these requirements/recommendations on the basis that they have been demonstrated to be safe, & that the test is onerous enough to allow a bit of a margin of safety, to cope with some of the vaguaries of installation (& thus performance) you're inevitably going to get in the construction industry.
The subtleties of the testing regime & it's lack of 'reality' are often forgotten - I've lost track of the number of times I've come across people assuming that they can sit behind a one-hour fire resisting construction quite happily for an hour, if there's a fully developed fire on the other side! I prefer the maritime ratings, where you have 'B', 'A' and 'H' - class fire-resisting structures - being 30, 60 and 120 minutes F/R and separating low-to-high risk areas respectively. Much less open to misinterpretation!
Having said the above, the tests aren't bad, so long as their limitations are recognised - & it's interesting to note that the standards for fire resistance tests are more or less the same throughout the world (unlike most other types of fire test).
Lastly, on the subject of the seals on fire doors, they have two main functions. Firstly they expand to stop smoke and hot gases exploiting the gap between the door leaf and the frame (or between the two door leaves, in double doorsets). Secondly, as Auntie Lin says, timber doors bend and bow when they are attacked by fire from one side - the timber shrinks as it dries out and this causes the door to bow away from the fire at its middle & towards the fire at its corners. This 'dishing' can be very significant and is the main reason that many timber doors fail the test, rather than burning through the bulk of the door leaf. That's why it's more or less impossible to calculate the fire resistance of timber doors based on charring rates alone, because it doesn't take into account this distortion. Some seals exert enough pressure to 'clamp' the door leaf in the frame and stop the edges bowing out of the rebate.
There is a third function on non-latched doorsets - they hold the door leaf in the frame once the door closer has stopped working (normally 10 to 15 minutes into the test, if face-fixed).
-
Hi Auntie Lin & Fishy
I understand completely the rationale behind intumescent strips and the way they are tested. I also understand the behaviour of fire doors during fire. I remain largely unconvinced however that intumescent strips offer any real benefit, other than property protection, in most buildings, and thus care needs to be taken by enforcers and assessors alike as to how far they go when pushing for existing fire doors to be upgraded where they are found not to be of the correct standard.
You could argue that the duty to mitigate the effects of fire under the RRO, and the fact that any fire safety plan should not include any reliance on the fire service means that intumescent strips do still have a role to play in some way shape or form.
But this would only be from a building protection viewpoint, not life safety. (save for some premises such as defend in place strategies or large complex buildings where evacuation would be long and protracted)
More and more buildings nowadays have some form of early warning or detection, early detection means quicker evacuation, and hopefully that means the fire service gets called out much quicker too.
And whilst any fire safety plan shouldn't rely upon fire service intervention, early detection does lead in all but a few case to early intervention.
Ive even been to incidents where the fire has been burning for quite sometime before we were called out, and yet still the intumescent hasn't activated. I dont buy the argument that early intervention is a factor in why we dont see many strips activate.
Imagine you are an enforcer or assessor standing in an 60 bed hotel. The doors to each bedroom are fire resisting to 30 minutes standard, are fitted with cold smoke seals and positive self closing device. There aren't any intumescent strips however.
Are you going to issue them a report saying all bedroom doors should be upgraded within 6 months, or would it not be better to suggest that when the fire doors need to be replaced the new fire doors meet current standards?
-
Midland Retty - you say: "The doors to each bedroom are fire resisting to 30 minutes standard, are fitted with cold smoke seals and positive self closing device. There aren't any intumescent strips however."
How are you identifying that they're 30 minute doors? Is it the nice blue plaque on the door which says 'Fire Door - Keep Closed'? Or the fact that the leaf feels heavy? Or that it's a thick door? None of these are accurate ways of determining the fire resistance of a doorset - you're just guessing. Could it be that the doors carry some form of plug and/or label? In which case they MUST have fire seals because they will have been tested with them and you can't claim the performance without. However...........if you are happy to undertake a risk assessment and provide the property owner with your written opinion that the doors will be fine without fire seals, everyone will be content, won't they?
-
Auntie Lin
I wont answer the part about how I identify fire doors, needless to say I dont just check how heavy they are, or if they have a nice blue plaque, have three hinges, go clunk click when they close onto their rebates or any of that nonsense as you suggested.
But you haven't answered my question, what benefit are instumescent strips from a life safety point of view? (other than some buildings Ive mentioned time and time again)
Another question Auntie Lin, and Im not being antagonistic here, but lets say you go into an office block. The doors look like 30 minute fire doors, but have no markings. Because there is nothing to suggest they are 30 minute doors would you ask the RP to change them all for certified fire sets?
-
Hi Auntie Lin & Fishy
I understand completely the rationale behind intumescent strips and the way they are tested. I also understand the behaviour of fire doors during fire. I remain largely unconvinced however that intumescent strips offer any real benefit, other than property protection, in most buildings, and thus care needs to be taken by enforcers and assessors alike as to how far they go when pushing for existing fire doors to be upgraded where they are found not to be of the correct standard.
You could argue that the duty to mitigate the effects of fire under the RRO, and the fact that any fire safety plan should not include any reliance on the fire service means that intumescent strips do still have a role to play in some way shape or form.
But this would only be from a building protection viewpoint, not life safety. (save for some premises such as defend in place strategies or large complex buildings where evacuation would be long and protracted)
More and more buildings nowadays have some form of early warning or detection, early detection means quicker evacuation, and hopefully that means the fire service gets called out much quicker too.
And whilst any fire safety plan shouldn't rely upon fire service intervention, early detection does lead in all but a few case to early intervention.
Ive even been to incidents where the fire has been burning for quite sometime before we were called out, and yet still the intumescent hasn't activated. I dont buy the argument that early intervention is a factor in why we dont see many strips activate.
Imagine you are an enforcer or assessor standing in an 60 bed hotel. The doors to each bedroom are fire resisting to 30 minutes standard, are fitted with cold smoke seals and positive self closing device. There aren't any intumescent strips however.
Are you going to issue them a report saying all bedroom doors should be upgraded within 6 months, or would it not be better to suggest that when the fire doors need to be replaced the new fire doors meet current standards?
I hear what you say, & disagree with some aspects of it, as I've stated above - particularly on the view that the strips are considered to have no life safety function. However, if you believe that you've got sufficient justification to support variation from the relevant good industry practice, then I guess we'll just have to agree to disagree.
The answer to your final question is that it would depend upon the risk, & I would also have the determination that I've referred to above in mind. As I've stated a number of times above, upgrading is not necessarily expensive, so if I considered that the risk warranted it then of course I would recommend it.
-
What life safety function do you believe intumescent strips perform? in what circumstances? what type of premises?
-
If the seals stop the fire from passing to an adjoining area in less than 30 minutes, isn't that a worthwhile life safety function?
-
But of course, however based on my experience I'm not sure that actually happens, which is why I keep pressing the issue. And as I said before care needs to be taken by enforcers and assessors alike as to how far they go when pushing for existing doors to be upgraded where they are found not to be of the correct standard.
I also would re-iterate my question Auntie Lin, lets say you go into an office block. The doors look like 30 minute fire doors, but have no markings. Because there is nothing to suggest they are 30 minute doors would you ask the RP to change them all for certified fire sets?
-
I defy anyone to positively confirm a door is FD when it is not marked ;D
All you can do is tick off the mental checklist
Anyway, all this supposes the frame/surround is up to it
I do however agree that in certain situations then IS is required, ie sleeping risk
davo
-
What life safety function do you believe intumescent strips perform?
They help hold back fire for longer.
in what circumstances?
In such circumstances that would involve a building being on fire.
what type of premises?
In premises which are on fire.
* CivvyFSO lays the bait and waits patiently.....
-
What life safety function do you believe intumescent strips perform?
They help hold back fire for longer.
in what circumstances?
In such circumstances that would involve a building being on fire.
what type of premises?
In premises which are on fire.
* CivvyFSO lays the bait and waits patiently.....
Here comes a big hungry fish Civvy so watch your elbows.
If we require 30min doors to protect some escape routes why do work around the 2.5 - 3 mins evacuation principle, even when detection is installed?
-
Retty they are particularly important where that door is fitted to maintain the compartmentation of a building to stop it falling down on our brave firefighters as they battle to contain a fire (I am talking Building Regulations here not Fire Safety Order).
Elsewhere their value depends on so many other factors- the nature and use of the building, its contents, the life risk and response and evacuation strategy etc.
We have to have some kind of measure of performance and some safety margins built in. The ultimate test is how many people die in a fire due to a failure of fire doors. Not many. But if we lowered the standard more people would die.
Our standards have developed and been refined over many years and we have a benchmark- BS476 part 22 and 31 in some cases for new doors, BS476 part 8 for older doors and BS459 for the very oldest doors. All were measurable standards. We know that a part 8 door would fail the part 22 test. No matter how good a fit it is. Whether that matters in a real fire or not depends on how good condition the old door is, how the building is used, the evacuation strategy and management etc.
I agree with you that it is wrong and often futile to automatically require all part 8 doors to be upgraded without consideration of the other factors. The recent case in respect of a historic hotel leads us to think that the Secretary of State is inclined to disagree with us.
Now whilst I have some power to vote him out of office he can put me in prison.
-
I defy anyone to positively confirm a door is FD when it is not marked ;D
All you can do is tick off the mental checklist
Davo
Hiya Davo
Is that a new symbol for fire doors in your posting? looks more fun than the old dots.
Did I not show you the Basil Fawlty Knock? Works a treat for me.
If my clients dont like the knock technique my 100mm hole saw allows close internal inspection of the door construction. I recommend sampling the door in 5 or 6 locations especially near the top.
Hey does this put me to the top of your your mental list? ;)
-
Hi Prof
Which is of more benefit, IS or properly installed frames?
Here are a few examples from a 2 hour FFS currently being installed (goes instantly grey... (all right, greyer :'()
http://s690.photobucket.com/albums/vv266/DavoB/?action=postupload
davo
-
Frames for life safety I would say. Strange mix of materials in use there. Is that new work going in or is it the stuff you are taking out (I hope?)
-
I think we are going to have to agree to disagree on this one folks. I still remain unconvinced and care needs to be taken not to over specify or require I/S
Ive already stated many times there are some exceptions where strips are required for life safety.
Kurnal you will admit from your response therefore that I/S are a building protection measure not life safety, and dont forget we are talking about the fire safety order here which only pertains to life safety (including measures for the protection of firefighters in some circumstances)
-
I think we are going to have to agree to disagree on this one folks.
Kurnal you will admit from your response therefore that I/S are a building protection measure not life safety, and dont forget we are talking about the fire safety order here which only pertains to life safety (including measures for the protection of firefighters in some circumstances)
Oh no we are not .
Retty you can duck and weave as much as you like there is other fire safety legislation than the Fire Safety Order that covers life safety from fire. Nowhere have you said that you were only wishing to discuss the Fire Safety Order definitions.
Indeed the Building Regulations 2000 are explicit- look at the explanation in respect of the limitation on requirements on page 5 of ADB which takes considerations of life safety far beyond the "Relevant Person" concept of the FSO. Its the Building Regs table B1 that sets out standards for fire doors.
I reckon you owe me a pint for leading you back towards the straight and narrow.
-
The Building Regs only apply when you are doing building work or a change of use (as defined blah blah)
Fitting new fire doors = do it properly to recognised standard
Risk assessment in exisitng building = do what's reasonable, taking into acount the actual fire risk specific to the premises (ADB just makes assumptions based on purpose groups).
-
Oh no we are not .
Retty you can duck and weave as much as you like there is other fire safety legislation than the Fire Safety Order that covers life safety from fire. Nowhere have you said that you were only wishing to discuss the Fire Safety Order definitions.
Indeed the Building Regulations 2000 are explicit- look at the explanation in respect of the limitation on requirements on page 5 of ADB which takes considerations of life safety far beyond the "Relevant Person" concept of the FSO. Its the Building Regs table B1 that sets out standards for fire doors.
I reckon you owe me a pint for leading you back towards the straight and narrow.
There is no ducking, diving or any pints on offer Prof.
As wee B has stated ADB applies to alterations / change of use / new builds
I have never argued that if you are installing new doors they should be of the correct standard. I am in full agreement that if new doors are going in they should include intumescent strips as that is reasonable.
Im talking here of existing doors and in particular the financial implications and reasonableness of insisting that the doors must be upgraded simply because they dont have intumescent strips.
And I still havent had any answer that convinces me that intumescent strips are in most situations for life safety protection, because if people are still in the building by the time they have activated (except for places with stay put policies, excessive evacuation times that is) something has gone horribly wrong.
So if you would like to lead me to the bar and get the beers in I will happily accept your humble apology.
-
If we require 30min doors to protect some escape routes why do work around the 2.5 - 3 mins evacuation principle, even when detection is installed?
It is not a 30 minute door. It is a FD30 door. :-X
If everyone always got out in 2.5 minutes we wouldn't really need much of a fire & rescue service would we? It gives a nice margin of safety to allow for rescues, first-aid, the bloke who is sat on the loo reading the Daily Sport, etc.
-
because if people are still in the building by the time they have activated (except for places with stay put policies, excessive evacuation times that is) something has gone horribly wrong.
Maybe they are that little bit extra for the times when something has gone horribly wrong?
-
If we require 30min doors to protect some escape routes why do work around the 2.5 - 3 mins evacuation principle, even when detection is installed?
It is not a 30 minute door. It is a FD30 door. :-X
If everyone always got out in 2.5 minutes we wouldn't really need much of a fire & rescue service would we? It gives a nice margin of safety to allow for rescues, first-aid, the bloke who is sat on the loo reading the Daily Sport, etc.
Awfully big margin. What would that equate to percentage wise?
-
Retty would you accept if you do not have I/S then you have a FD20, maximum and not a FD30 door, but it may be adequate in some circumstances.
-
I don't require all doors to be upgraded in one go - it all depends on the usage & layout of the premises, the expectations of the door, the occupancy type & numbers, the condition of the doorset, etc
I do always mention that they are not to the latest spec and may not perform as well and that they should be upgraded progressively (ad-hoc rater than within a time limit) and not replaced like for like (i've seen enough examples of a door being replaced due to wear and tear, but instead of a current FD30/FD30S doorset just the FD30 leaf is put back in still relying on a tight fit to a 25mm rebate).
If there is a high risk occupancy that requires immediate or scheduled upgrade then I rarely just specify seals anyway and often require upgrade FD30S with combination seals and smoke brushes as it's the smoke spread that is the first concern and the cost differential isn't too much in the grand scale of things.
-
Awfully big margin. What would that equate to percentage wise?
Well there is a huge difference between someone who is capable of getting up and walking out of the building in 2.5 minutes and someone who is hurt or needs assistance.
-
Awfully big margin. What would that equate to percentage wise?
Well there is a huge difference between someone who is capable of getting up and walking out of the building in 2.5 minutes and someone who is hurt or needs assistance.
Why might they be hurt Civvy?
Thats the first evacuation strategy I have come across which has rescue or assistance factored in to the time. :-\
-
Im glad that we can rest assured that all fires will behave like a 476 test. ;)
-
I have never argued that if you are installing new doors they should be of the correct standard. I am in full agreement that if new doors are going in they should include intumescent strips as that is reasonable.
Im talking here of existing doors and in particular the financial implications and reasonableness of insisting that the doors must be upgraded simply because they dont have intumescent strips.
And I still havent had any answer that convinces me that intumescent strips are in most situations for life safety protection, because if people are still in the building by the time they have activated (except for places with stay put policies, excessive evacuation times that is) something has gone horribly wrong.
So if you would like to lead me to the bar and get the beers in I will happily accept your humble apology.
Sorry Retty I had misunderstood you on two counts.
First I thought that you were discussins seals in all situations not just the scenario of "upgrading" a part 8 door with seals in the hope of achieving a part 22 equivalent.
Secondly just for a minute I thought you said I was to buy the drinks. That cannot be right.
-
I have never argued that if you are installing new doors they should be of the correct standard. I am in full agreement that if new doors are going in they should include intumescent strips as that is reasonable.
Im talking here of existing doors and in particular the financial implications and reasonableness of insisting that the doors must be upgraded simply because they dont have intumescent strips.
And I still havent had any answer that convinces me that intumescent strips are in most situations for life safety protection, because if people are still in the building by the time they have activated (except for places with stay put policies, excessive evacuation times that is) something has gone horribly wrong.
So if you would like to lead me to the bar and get the beers in I will happily accept your humble apology.
Sorry Retty I had misunderstood you on two counts.
First I thought that you were discussins seals in all situations not just the scenario of "upgrading" a part 8 door with seals in the hope of achieving a part 22 equivalent.
Secondly just for a minute I thought you said I was to buy the drinks. That cannot be right.
Apology accepted Prof, and I never "discussins" anything.
I would echo the comments from Nearlythere and FSO and Civvy are you laying bait again?
-
Prof
er, new stuff, :'(
For some strange reason I find myself drifting towards Retty on this one........
davo
-
Thats the first evacuation strategy I have come across which has rescue or assistance factored in to the time. :-\
So what standard should we accept for doors? Should we create a new test for a FD2.5 door that will last 2.5 minutes of the heating regime? In fact why do we even need doors if we can guarantee that everyone is out in 2.5 minutes? I could probably prove with a bit of maths that conditions would be tenable 2.5 minutes after an alarm went off in almost any premises. Shall we engineer it perfectly so that the whole building falls down the moment the last person is expected to reach safety? After all, why do we want 30 or 60 minutes of structural fire resistance when everyone will be out?
Have a look at PD7974-6, the pre-movement time for any poorly managed premises is given as over 15 minutes. Where does this fit in with the magic 2.5 minutes? Are the people who had input to this BS wrong?
Now have a look at the details behind the recent New Look prosecution, see if people were out of the premises in 2.5 minutes after the alarm going off. 5 minutes? 10 minutes?
-
Have a look at PD7974-6, the pre-movement time for any poorly managed premises is given as over 15 minutes. Where does this fit in with the magic 2.5 minutes? Are the people who had input to this BS wrong?
Civvy The 2.5 minutes is one part of the evacuation time and between 10 to 20 minutes is more realistic time for full evacuation for medium sized buildings. For me this was born out when witnessing evacuation drills in SME's.
-
I think I wasn't clear with any elements of sarcasm or what may be construed as rhetorical questions in the post. I wasn't questioning the BS, I was really questioning NT's the 2.5 minutes, essentially in line with what you say.
The way I look at it is: The 2.5 minutes as merely an 'optimum capacity' built in. i.e. The door is capable of getting x amount of people through, in y time.
-
Thats the first evacuation strategy I have come across which has rescue or assistance factored in to the time. :-\
So what standard should we accept for doors? Should we create a new test for a FD2.5 door that will last 2.5 minutes of the heating regime? In fact why do we even need doors if we can guarantee that everyone is out in 2.5 minutes? I could probably prove with a bit of maths that conditions would be tenable 2.5 minutes after an alarm went off in almost any premises. Shall we engineer it perfectly so that the whole building falls down the moment the last person is expected to reach safety? After all, why do we want 30 or 60 minutes of structural fire resistance when everyone will be out?
Have a look at PD7974-6, the pre-movement time for any poorly managed premises is given as over 15 minutes. Where does this fit in with the magic 2.5 minutes? Are the people who had input to this BS wrong?
Now have a look at the details behind the recent New Look prosecution, see if people were out of the premises in 2.5 minutes after the alarm going off. 5 minutes? 10 minutes?
The fire resistance performance ratings that are in all the guidance do not equate to evacuation times & should not be used as such. The tests used to generate these ratings are not particularly ‘realistic’ (and they were never intended to be so).
20/30/60/120 minutes fire resistance are simply rankings and which applies is based on the code-makers appreciation of the risk associated with the fire resisting element in question. If its medium/low risk then you specify 20 or 30 min; higher risk installations attract a 60 minute rating; higher risk, protection to fire-fighters and protection of other premises is typically achieved by specifying 2 hours. Nowhere in the tests themselves or certification of such elements does it say that they will ‘survive’ for these times in a real fire. In fact, it’s almost certain that their performance will be completely different, because it is very unlikely that any real fire will mimic the thermal characteristics of a fire resistance test furnace (which is basically a modified gas-fired crematorium)! ASET/RSET calculations that use the ratings as a definitive measure of fire-survivability typically fail to appreciate this point.
The good people who came up with these test methods & ratings in the early part of the last Century knew all this – the ratings are deliberately set quite high because they knew that, in the construction industry, quality of design & installation could be so variable. Setting the ratings high, in relation to the time needed for escape when a fire is fully developed, gave some confidence that the foreseeable variation in quality control of these works would not reduce fire resistance below the necessary level.
-
Intumescent seals for life safety or property safety?
I was investigating a fire in a property that was separated into different flat units. The fire was in the ground floor flat and was impacting on the door between the flat and the stairway. The occupier of the upper flat staed that he had to jump past the flames that were emitting from the edge of the door in order to get past it as he made his escape. Witnesses confirmed that the fire alarm had been operating for 5 minutes before the first annoyed resident came to reset the system, saw the smoke and knocked on all the doors to clear the building. The building was clear within 8 minutes of the alarm sounding.
The building was protected by a BS 5839-1 L2 system which had been checked for compliance 7 days before the fire. The detector within the fire compartment was an ionisation smoke detector. My concern was how were flames emitting from the edge of a fire door within 8 minutes of the smoke alarm operating, such that occupants had to jump past the flames in order to escape?
I was drawn towards the NIST studies carried out in the States as a result of the number of peopple who were being killed in house fires when smoke detection systems were installed and functional.
The report pointed to a set of circumstances where an ionisation smoke detector would take 20 minutes longer to detect a smouldering fire than an optical detector would in the same circumstances. The fire ine this instance had been burning for a lot longer than 8 minutes, and the circumstances closely matched those of the NIST studies.
The intumescent strip had actuated which delayed the impact of the fire onto the stairway. This door did not, I believe, withstand fire for 30 minutes, as discussed in earlier posts, but it certainly lasted in the region of 20 minutes. The fact that occupants took those same 20 minutes to evacuate would support the need for strips for life safety. Or would at least support the need for justification not to work towards fitting them over a reasonable period.
Whilst not definitive in any sense of the word, my experience in this and other investigations leads me towards encouraging the installation of intumescent seals over a reasonable timescale unless there are extremely good reasons not to.
-
I have always belived the need for intumescent and cold smoke seals for life safety.
In the incident you mention if the seals had activated correctly and the door was a good fit then surely flames should not have passed.
I have investigated a fire in multi storey flats where the smoke has spred from a bin room through three old type fire resisting door sets and entered flats. Non of the doors wer fitted with either seal but had the 25mm rebates which do nothing to prevent smoke spread.
There is an old BRE document Digest 320 "Fire Doors" from 1988 which is an interesting read and explains why seals are now fitted.
If you have trouble finding a copy email me.