whitepaper - design considerations when integrating smoke and fire curtains

Design considerations when integrating smoke and fire curtains into a building

Your next steps:

Call us: +44(0)23 9245 1111

Email us: [email protected]

Visit our website: www.coltinfo.co.uk

(c) 2015 Colt International Licensing Ltd.

Whitepaper

Colt whitepaper - Design considerations when integrating smoke and fire curtains into a building

This whitepaper covers:

What are smoke curtains and fire curtains and what are the key differences between them

The standards which each type of system has to comply with

The design aspects to consider when integrating these systems into a building

Installation, use, testing and maintenance.

1. The differences between smoke curtains and fire curtains

A smoke curtain is basically used as part of a smoke control system. It is there to either stop smoke reaching another zone or to channel smoke through a particular route that we want it to take. As such it will normally be up at high level, well above head height, and in most cases smoke curtains dont descend down to ground level.

A fire curtain, on the other hand, is used to provide fire separation between two spaces. It may well provide smoke control at the same time, but that is not its primary purpose, which is to prevent the spread of fire, and typically it may be used to protect a lift door or an escape route through an open plan dwelling.

In terms of its performance, a smoke curtain is only expected to be exposed to smoke, so it is rated to 600oC. A fire curtain, on the other hand, may well be exposed to the fire itself and fire temperatures can be a lot higher. So the fire curtain is fire rated against the normal ISO fire curve, which exceeds 1000oC, so it is a much higher rating and the curtain needs to be more robust in order to achieve that. If you try to use a smoke curtain in an application where a fire curtain is needed then the smoke curtain simply will not be robust enough to withstand the fire temperatures.

2. The differences between smoke curtains and smoke barriers

The terms smoke curtains and also smoke barriers are very often used interchangeably. However in practice a smoke barrier is anything which will prevent the transmission of smoke, whereas a smoke curtain is generally used to describe a fabric curtain, whether it is fixed or movable. As stated above, the purpose of smoke barriers is generally to withstand temperatures of up to about 600oC and really any material which will withstand that temperature would be suitable as a fixed barrier. So a fixed barrier will look something like this:

In this case it is a flexible material, permanently mounted at high level, so that if there is a fire then we can open the smoke ventilators on both sides but keep the smoke one side of the barrier, so the rest of the area is protected.

The reason the curtains are rated to about 600oC is that flashover is expected to occur in a building once the smoke temperature reaches around 600oC, so basically once that temperature is exceeded, the smoke curtain is not going to do anything anyway, so there is no point in rating it above 600oC.

Summary

Fire curtains and smoke curtains are very commonly mixed up and the terminology around them is of-ten interchangeably and wrongly used. This white paper examines what a smoke curtain is and what a fire curtain is, explaining how they are designed, the standards and test regimes that apply to each, and how they are each expected to be applied.

2


3

3. Fixed versus movable smoke curtains

As an alternative to a fixed curtain, a movable curtain will be held up above the ceiling level most of the time, and then once a fire occurs and has been detected, the curtain will drop to its operational position. This is usually done simply for architectural purposes. Nobody is going to be concerned about seeing a fixed screen at high level in a large warehouse. By contrast in a shopping centre or an atrium architects want to keep any smoke barriers out of sight until they are actually needed for operational purposes.

Typically an automatic smoke curtain will be a fabric wrapped round a motorized roller, although there are other designs available, such as concertina designs.

A moveable smoke curtain providing escalator containment

4. Smoke versus fire curtains

Smoke and fire curtains look similar to each other, but they have very different properties and uses!

A fire curtain is generally installed so as to replace a conventional fixed element such as a door, shutter or even a wall. A fire curtain is always movable: the reason it installed is simply because we want to make use of an opening that is available for everyday use which can also be closed off in the event of a fire.

In terms of their construction, movable fire curtains are fairly similar to movable smoke curtains but there are two quite important differences. The first one is that the fabric itself is generally more robust to withstand the higher temperatures, and to achieve this the glass fibre woven material generally includes a stainless steel filament which gives it higher strength at high temperatures. The other difference is that with a smoke curtain side guides are not normally required, but this is the opposite for a fire curtain: side guides are always required, because it is necessary to ensure that there is a complete system with no gaps for the fire to get through. So smoke and fire curtains are similar in appearance but a lot of detailed design aspects are different.

Most of the rollers are limited to fairly short lengths, typically around 4.5 to 5.0m, and around 80100mm in diameter. The roller diameters are kept relatively small so that the headboxes can be kept small; if the roller was larger in diameter, then longer single curtains could be manufactured but then the roller would be physically much larger and much more difficult to fit into the building.

So to make curtains above that 4.5 to 5.0m length, then multiple rollers and overlapping curtains are installed; the rollers may be either side by side or one above the other, and this simply depends upon what is most convenient in terms of the space available.

Side guides are available for smoke curtains for some applications but the vast majority of smoke curtains wont have any, since it is regarded as acceptable for there to be a bit of smoke leakage around the edges of the curtains. See page 8 onwards for details on the role of side guides with fire curtains.

5. Construction of a movable smoke curtain

A movable smoke curtain comprises a roller which normally has an integrated motor and bearings. The roller will have fabric fixed onto it. This fabric is rolled around it and as the roller turns the fabric will rise or drop. At the bottom of the fabric there is a weighted bottom bar and normally at the top of the curtain there is a headbox which contains the mechanism.

The bottom bar has two principal functions. Firstly, it provides a weight at the bottom of the fabric so that when the power is removed from the roller motor then gravity acting on the bottom bar weight makes the curtain drop. This assumes that the curtain is a gravity drop type, which most curtains are actually are, though some curtains are driven down to meet some unusual applications. The other function is to limit the deflection of the curtain if it is subject to high pressure differentials or air velocities. If the curtain flaps around excessively when it is in use then it is less effective, so the heavy weight of the bottom bar actually stops the fabric from deflecting too much.

1 - Non-flammable glass fibre cloth2 - Extruded aluminium bottom bar3 - Weight profile

1

2

3


4

Headbox assembly containing a single roller

Series of rollers mounted next to one another in a horizontal configuration to form a continuous run of curtains set within a headbox

Series of rollers mounted above one another in a vertical configuration to form a continuous run of curtains set within a headbox


5

6. Smoke curtain controls

There normally is a zone control panel and a local battery back-up (BBU). A BBU is mainly to prevent nuisance dropping of the smoke curtain, for example in case of a loss of mains power. A BBU is not essential in terms of fire operation because the curtains will fall automatically under gravity when the

7. Standards and testing for smoke curtains

In the UK smoke curtains have to comply with the EN 12101 Part 1 Product Standard. This is a harmonised Standard to the Construction Products Regulation and therefore smoke curtains have to be CE marked.

Sample EC Declaration of Conformity

(a) The product will need to have a heat exposure test, which exposes the curtain to 600oC for a minimum of 30 minutes, although most curtains are rated to either 60 or 120 minutes, because a smoke curtain which will pass the test for 30 minutes will typically also pass it for 60 to 120 minutes without any problems.

A smoke curtain under fire test

(b) In addition there is a 1000-cycle reliability test. This is not because the curtain is expected to be raised and lowered in normal day to day usage, but obviously these systems are expected to be regularly tested and the 1000 cycles equates to 20 years of testing the curtain once a week.

(c) There is also a response time requirement to make sure that the curtain does actually drop immediately once the power is removed.

(d) There is a speed of descent requirement, because whilst it is important that the curtain will drop at a reasonably fast rate, it should drop so quickly that it will either frighten people or cause significant injury if it actually drops onto somebody.

power is lost. However where a drive-down curtain is needed, for example in situations where multiple or intermediate potential drop positions are required, or where the curtain is running horizontally rather than vertically, then of course a BBU is required to be sure the curtain will deploy in a fire condition.

So the Standard prescribes a minimum speed of descent of 0.06 m/s and a maximum speed - depending on where the curtain is located of either 0.15 m/s or 0.30 m/s. The 0.15 m/s speed is intended for curtains which descend below 2.5m, so that there is very little risk of them clashing or hitting people at this sort of speed.

(e) The other thing that the Standard covers is the need to measure gaps and limit gaps around the edges of the curtain to make sure that there isnt too wide a gap which could cause excess smoke leakage past the curtain.

The Standard also applies to static barriers, so any purpose-designed fabric smoke barrier should be certified to the Standard as well.

Theres a bit of a grey area about whether the Standard applies to products such as fire rated glass or fireboard when they are being used to create a smoke barrier. If a product is being marketed as a smoke barrier, then it definitely should comply with the Standard and be CE marked. On the other hand if as a specifier you have decided that you want to use fire rated glass as your smoke barrier, then thats fine: it probably wont need to be CE marked, but you certainly would need to be able to prove to Building Control that whatever product you are using is at least equivalent to a smoke curtain tested to the Standard.

Instead of an application Standard, which does not exist, there is BR 368, which gives a little bit of guidance on smoke barriers, but it is quite an old guidance document now and some of the guidance is out of date. There is also a limited amount of guidance in BS 7346-4, which covers the calculation of the deflection of smoke curtains, smoke reservoirs and smoke depths.

The Building Regulations of England and Wales make no direct mention of smoke curtains; they are referred to in BS 5588, which then may then refer to BS 7346-4.

Colt International GmbHBriener Str. 18647533 KleveGermanyTel. +49(0)2821 990 0

www.coltgroup.com

Autom. Smoke Curtain ASB (EN 12101-1: 2005+A1: 2006)SM5/2/DH/N/G/5300/1000/2/25/X/K/X/X/X/D120/PSWeight [kg] : 108Fire Class : D120Passage of fabric [m/h] : 0.3/200Ct amp : -5C to 60CClassification report : 0672-CPD-0144Response delay :


6

8. Applications for smoke curtains

Typical applications for smoke curtains are as smoke reservoir boundaries, channelling screens, void edge screens, void sealing screens, corridor containment, shop unit containment, escalator containment, stairwell containment and elevator well containment. We illustrate four more typical applications here:

(a) The most common application is to create a barrier so as to assist in creating a smoke reservoir. That may be in a warehouse, a shopping mall, factory, infact in any building where the aims are to provide a limited smoke reservoir where smoke can be contained before it is extracted and to prevent smoke spilling through to the rest of the building. The smoke barrier itself will therefore be at high level and it needs to descend down to at least the depth to which the smoke itself is expected to descend.

There are some differences in the guidance documents in terms of how large a safety margin is needed below the calculated smoke layer depth. CIBSE Guide E states that there is no safety margin needed and that the bottom of the barrier should be at least as low as the bottom of the smoke layer. BS 7346-4 states that a 100mm safety margin is needed. The old Smoke Ventilation Association guide recommends a safety margin of 500mm. So, there are various pieces of guidance and it is down to the designer and their suppliers as designers to decide which is applicable. Colt does not recommend that CIBSE guide E guidance (with its lack of safety margin) is followed, simply because it assumes nice flat bottom to the smoke layer and it is well established that in practice the layer is actually going to move about a bit, so some form of safety margin is very sensible.

(b) Another application for smoke barriers or smoke curtains is as channelling screens.

The illustration here shows barriers mounted underneath a balcony. In this scenario it is expected that smoke will spill from a shop unit or an office under that balcony and then up through a mall or atrium. The wider the spill plume is from the balcony, the more smoke is going to be generated and the larger the amount of smoke ventilation will be required.

So, by limiting the width of the spill plume, the size of the smoke ventilation plant can be reduced with resultant reduction in costs. This is done by dropping barriers across underneath the balcony; those can be automatic smoke curtains or they can be fixed screens. It is quite common for architects to make a virtue out of necessity and put in fixed screens which are then used as advertising hoardings, and as long as those are rated to withstand 600oC. Again, any material is perfectly acceptable.

(c) Another application for smoke curtains is as balcony edge screens. In this instance, rather than to limit the width of the spill plume, the aim is to avoid smoke actually from spilling from the balcony into the atrium or mall above. In this case there would be smoke extraction from below the balcony and the screens would need to descend to at least cover the expected depth of the smoke under the balcony. It is not a common solution, but occasionally it becomes necessary.

(d) The final common application for smoke curtains is for atrium balcony protection. The image shows smoke curtains descending right down to floor level, which basically protect people on the balcony from smoke from within the atrium.

Atrium balcony protection

So in this case smoke is expected to spill so as to fill a large proportion of the atrium. However because the balcony is used for escape, then rather than allowing the smoke to spill into the balcony, then we need smoke curtains across there to separate the balcony from the atrium. This not an application which is commonly seen in the UK, but is seen quite a lot in places like South East Asia; it just comes down to different design methods for different territories, and its a perfectly acceptable good solution.


7

9. Installation aspects and potential issues

In order to be sure that a smoke curtain installation remains in good working order, attention needs to be given to the following installation aspects at the design stage:

(a) Access for maintenance and repair. Since smoke curtains are inevitably mounted at high level and architects normally want them to be hidden away, they very often actually have all their mechanisms above the ceiling. The bottom bar is the only component that is visible in normal use; when the curtain is deployed then the curtain material itself plus the bottom bar becomes visible, but the roller and headbox are never visible.

If it is necessary to maintain or repair anything within the headbox, then access to the headbox is required. Very often a curtain is installed and then the ceiling installer simply plasters right up to the headbox leaving no access for maintenance and repair at all, meaning that if there is a problem in the future the ceiling has to be ripped out in order for the system to be maintained. So it does make sense to look at where maintenance access is going to be needed and to provide access panels at that point.

(b) Location of the controls and the battery back-up. Ideally these components are positioned close to the motor and the headbox, but they themselves are generally not actually temperature-rated, so they do need to be positioned somewhere which is protected and they also, of course, need to be somewhere where they can be accessed for maintenance in the future.

(c) Air movement can be an issue as well. If a fixed curtain is placed in a location where there is regular and significant air movement, then that curtain can flex, perhaps rip and cause a bit of noise and aggravation, so it is necessary to consider where the curtain is located and whether it is likely to be susceptible to excess air movement.

A billowing curtain

Air movement can also impact on the ability of automatic smoke curtains to function as designed. When the curtain is deployed, then excessive deflection and billowing can have two undesirable side effects. The first is to raise the bottom bar to above the smoke layer level - which is another good reason for having a good safety factor. The other potentially undesirable side effect is that a significant edge gap can appear, thereby allowing significant amounts of smoke to pass the barrier. Obviously if the curtain is located at 90o to a wall then edge gaps are not going to be a problem if the curtain billows, but if the curtain is located say at an angle to another or next to a column, then those edge gaps can become quite significant, and in those applications side guides may be required.

(d) Another key consideration is the location of the smoke curtain. The normal purpose of a smoke curtain is to control the smoke and keep it within a single reservoir, so therefore if the curtain is directly above the fire source then smoke from that fire source is probably going to move into two reservoirs and so the smoke curtain is not going to do its job. So therefore smoke curtains should always be above aisles or walkways wherever possible, and if they cant actually be above a walkway then certainly any major fire source (such as high bay racking or large pieces of machinery) should not be located directly underneath the curtain.

Location of curtains away from a potential fire source


8

10. Use, testing and maintenance of smoke curtains

Smoke curtains arent designed for daily use: there is no particular purpose in dropping them in daily operation, so their lifecycle is based upon them being tested once a week if it is part of a life safety system; other than that, annual maintenance is normally sufficient and as mentioned earlier if annual maintenance is required then access is needed for this.

Let us now turn to the design and application of fire curtains.

11. Construction of a fire curtain

A fire curtain looks pretty similar to a smoke curtain in construction: there is a roller with an integrated motor and bearings, a piece of fabric fixed to and rolled round the roller, a weighted bottom bar fixed to the fabric and a headbox to contain the mechanism.

The only additional component with a fire curtain is that side guides are now not an optional extra for occasional use, they are an integral part of the system and are required in every application.

There are also other detailed differences. The fabric itself has a different performance rating; the bottom bar will probably also be slightly different, because in this case it is expected that the bottom bar will descend right down to floor level. In addition, within the bar there is normally some sort of mechanism to ensure that a reasonable seal is achieved at floor level, even if there is a rough floor surface. If the bottom bar bows slightly under the heat, a connection to the floor rather than a gap has to be maintained.

12. Controls for fire curtains

Again controls and a battery back-up unit will be needed. With a fire curtain a battery back-up is not only required if the curtain is driven down to its deployed condition, but also if there are emergency access or egress controls, allowing the curtain to be raised after it has been lowered in order to allow people through the curtain either to enable people to escape or for fire fighters to go through.

A typical access panel arrangement


9

13. Standards and testing for fire curtains

There is a British Standard for fire curtains: BS 8524-1 is the product Standard and BS 8524-2 is the application Standard, and both were introduced in 2013. The product Standard requires the curtain to descend by gravity wherever possible, though obviously this is not always possible for horizontal or lightly sloping units, so in those instances they are allowed to be drive up, drive down.

(a) Fire resistance testing is specified by the above Standard, and in this instance testing is to much higher temperatures than for a smoke curtain.

(b) There are reliability tests involving cycle testing and in this case the requirements are for a relatively low number of cycles, similar to those used with smoke curtains, where the fire curtain is not expected to be used on a daily basis. However a fire curtain may well of course drop down to floor level, may be used instead of a fire door and there may be requirements for it to be dropped regularly, so there are options within the Standard to go up as far as 200,000 cycles.

(c) There is also an impact test, since because a fire curtain is expected to drop down to floor level, there is the risk of people knocking against them, and so therefore an impact test is part of the reliability testing.

(d) The speed of descent is similar to a smoke curtain: there is a requirement of a 0.15 m/s speed of descent if the curtain is dropping vertically below 2m, or 0.3 m/s either if it is moving horizontally or if it is dropping down to 2m from floor level (which is pretty rare).

(e) Smoke containment testing in this case is an optional extra in the same way as it would be for a fire door: you can test it as say E30 or E30S, and similarly a fire curtain can be tested with or without smoke containment.

(f) And finally where there is the need for accessories such as switches for egress and access or anything else, then those are tested as part of the testing regime.

It is worth noting that although the EN 16034 Standard for fire curtains has been published and accepted by the EU, it is only likely to come into force in the UK in 2016 or later. If a curtain is being used as a fire door or a fire shutter, then it should then comply with EN 16034 and it will need to be CE marked to this Standard. Generally if the fire curtain complies with BS 8524-1 it shouldnt have any problems complying with EN 16034 as that actually has lower requirements than the British Standard.

The BS 8524-2 application Standard gives a lot of useful guidance for example as to in what circumstances such a fire curtain would be used and which controls should be used for which curtains.

On the other hand the Building Regulations of England and Wales make no mention at all of fire curtains and there is no method of linking from the Regulations to any related standards or to any particular requirements. This is because fire curtains are a relatively recent development and the current version of ADB is relatively old (2006).


10

14. Applications for fire curtains

There are five typical applications that a fire curtain is used for:

(a) The obvious application for a fire curtain is as a direct replacement for a fire door or a fire shutter. It doesnt mean to say that the curtain will be used as a door in everyday use, but it would normally be intended to keep it open most of the time and just to close it in emergency or under test conditions.

(b) Fire curtains are also quite often used to protect lift doors. There is an application where the lift doors themselves are not fire rated but we need a fire rating at that location, then simply dropping in a fire curtain in front of the lift doors is a common way of providing this.

(c) Another reasonably common application is where there is a relatively large void being used as a smoke shaft, perhaps as an alternative to a BRE Shaft or an ADB Shaft, then that void can be closed off using a fire curtain. In normal circumstances such a shaft would be closed off using a damper or ventilator of some type, but a void is being used then that void would normally have quite a large opening, too big for a ventilator or damper, and therefore a fire curtain could be employed to close off the shaft on the levels where there is no fire.

(d) Another common application is in an open plan dwelling. In larger, more expensive architect-type dwellings, there is often quite a requirement for the ground floor to be open plan, which is architecturally very nice and very convenient for the occupants, but it does mean that if in the case of a fire people are trying to escape from the upper floors, then they might well have to pass by the fire to get to an exit. In such circumstances it is quite common to have fire curtains which will drop in case of fire to provide a protected route through from the upper floors to the final exit. Another common use is just as small curtains, basically replacing fire shutters across counters, serveries, service shafts and so on. The main reason that people would use a fire curtain rather than a fire shutter is simply that it tends to be smaller and neater and less expensive.

(e) The final application is as follows. As described above, smoke curtains can be used to allow escape along atrium balconies. If there is a narrow atrium balcony then it is quite common to be required to use a fire curtain rather than a smoke curtain for that particular application. This is actually one of the very few applications where it is very easy to get confused about whether a fire curtain or a smoke curtain is required.

15. Ratings of fire curtains

Where a barrier is fire rated, then quite often there is a requirement for the curtain to be rated for insulation and/or radiation. Insulation would be the ideal rating for a fire curtain but unfortunately it is quite difficult to test for insulation on a fire curtain.

The reason for this is twofold: one is that quite commonly insulation is provided by the means of an intumescent coating on the curtain material, and this will tend to grow during the fire and it is not easy to be sure that the thermocouple which it is mounted on non-fire side of the curtain will actually stay in place in the test. The other reason is that even if the curtain does not have an intumescent coating, the fabric normally has a coating which quite often heats and dissipates in case of fire, and if the coating is destroyed, then it gets quite likely that the thermocouple will fall off. Therefore it is technically quite difficult to test a curtain for insulation.

Because of this BS 8524-2 provides ways of using radiation data, because obviously with radiation data thermocouples are removed from the curtain and therefore it is much easier to test radiation than insulation. Within BS 8524-2 there are a number of methods ranging from very simple basic methods for small dwellings, through to much more complex fire engineering methods. Essentially the purpose is to ensure that in the escape route the radiation is sufficiently low to allow somebody to escape past a curtain without suffering excess heat or any injury.

Radiation table from BS 8524-2

This table from BS 8524-2 shows the length of barrier assembly along the escape route which people will have to walk past, and the longer that barrier is, then the lower the permitted radiation is. The data is for the test radiation under the normal test regime at 15 minutes into the test, and there is only a 1m long barrier then only 13.7 kilowatts per m2 up to 5 metres is allowed, at which point we can only allow 3.7 kilowatts per m2. These are very simplified values worked out by a Fire Engineering Consultant to give safe conditions in the tenable zone. There are of course other tables in the Standard which could be used for fire engineering, or it is possible to go to first principles and use basic calculations.


11

16. Controls

There are a number of operational modes for fire curtains and again these are all detailed within BS 8524. It is quite possible to have multiple position deployment: this could involve a curtain which would drop part-way, perhaps to provide smoke control in the early stages of the fire, hold at that for a set period and then dropped to provide fire protection at a later stage.

There is also the option for an emergency access switch which allows the Fire Service to raise the curtain in order to access the space on the other side, and thats arranged in such a way that when you press the switch the curtain raises, and as soon as you let go of it, it starts to drop again.

There is also an emergency egress switch for use by people escaping which allows the occupant to raise the curtain simply by pressing the switch once, when upon the curtain will raise to at least 2m; if the switch is held there for at least 5 seconds, then the curtain will drop again.

Obstruction warnings are recommended because obviously it is undesirable that people will any obstructions which will stop the curtain from deploying. The two options are either a beam protection system providing audible visual alarm, or for applications in warehouses the floor can simply be marked with areas where it is not permitted to provide any storage, even temporarily.


12

17. Installation aspects and potential issues

In order to be sure that a fire curtain installation remains in good working order, attention needs to be given to the following installation aspects at the design stage:

(a) Excessive velocities may cause the fire curtain to stick. In some cases if the smoke extract fans operate before the fire curtain deploys, then those extract fans can create quite a large pressure differential. Since a fire curtain has to overcome friction within its side guide rails in order to drop, it is possible for the curtain to actually stick part way down. So if the scheme design allows this to be a possibility, it is important that the curtain is made to close before the smoke extract fans start.

This is likely to be less of a problem with smoke curtains, where if the smoke extract fans start before the smoke curtains deploy, the bottom bar might just swing about a little bit.

(b) Possible need to calculate the likely deflection. Since a fire curtain always has side guides, deflection is much less likely to be an issue for a fire curtain than for a smoke curtain. However where a curtain is situated adjacent to an escape route, then it is necessary to know what the deflection is and allow for that in the selection of the width of the escape route to make sure that there is a suitable available width for people to escape through.

(c) Access for maintenance and repair. Again, as for smoke curtains, access and maintenance repair can be an issue, because the mechanism is always at high level, and if it is necessary to maintain or repair anything within the headbox, then access to the headbox is required. However In general terms it seems much more acceptable for the headboxes to be on display with fire curtains, but again if the fire curtain headbox is mounted above ceiling level then consideration needs to be given to access through the ceiling.

(d) Potential for obstructions. Compared to smoke curtains, obstruction is quite an important issue. In most cases smoke curtains do not descend anywhere near floor level, and nothing should be stored underneath them anyway, so this is probably not an issue. Since fire curtains descend down to low level, keeping obstructions out of the way is much more important.

(e) Timing of descent. The moment when the fire curtain should actually close needs close consideration. If people are likely to be wanting to escape through a route where the fire curtain is, then it makes sense to deploy the fire curtain as late as possible, whereas in other applications it makes sense to deploy the fire curtain early. So in some cases it will be deployed from a signal from the general smoke detection system, in other cases from a local smoke detector, and sometimes from a local fire detector. BS 8524-2 provides a table which very clearly states which systems are acceptable and under which circumstances.

(f) Maintenance regime. Finally in terms of use, testing and maintenance, in some cases automatic fire curtains maybe designed for daily use, although most are intended for emergency use only and this will be reflected in their reliability classes.

Maintenance should be to the manufacturers instructions: annual maintenance is normally sufficient but there are requirements in BS8524-2 for much more regular testing than is normally used for smoke curtains, and table shown here taken from BS 8524 shows the basic testing requirements:

Where there is no equipment providing obstruction warnings, that is to say when some markings are simply made on the floor to show an area where there should be no obstructions, then daily inspection is recommended to ensure that nobody has actually stored anything underneath the curtain.

As with smoke curtains, there is a recommendation for weekly operation of each unit, basically to check that it is working, a monthly check of any release mechanism self-closing devices, sensory detection equipment, etc., basically just making sure that the system is there and functions properly.

If the system is part of a smoke control system, then also there usually is a 3 monthly check that it actually works properly in conjunction with the smoke control system, and then every 6 months there is a check of any smoke seals: if it is a smoke sealed unit, then just a general structural check is needed to make sure that it is not damaged or bowed or deformed.

So there is quite a lot more testing set out in the Standard for a fire curtain as opposed to a smoke curtain, but since people never do more than what is asked for and they quite often do less, it is better to err on the side of safety rather than anything else.

Table 6 Inspection and testing of barrier assembly

Frequency Inspection and testingDaily Where no sensory equipment areas, e.g. by alterations to racking or by furniture or

Weekly Operate all barrier assembly control system protecting operated in conjunction with

Monthly Test the release of self-close test switch.

About ColtSince 1931 Colt has been harnessing the natural elements to provide healthy, comfortable and safe working and living conditions in buildings. Colt is a specialist in smoke control, climate control and HVAC systems, industrial ventilation and solar shading, with a presence in more than 50 countries.


18. Summary

Smoke curtains and fire curtains have significant differences and are not interchangeable. It is important to be sure about which one is needed, and to specify it properly. To make it simple to decide, fire curtains restrict the spread of fire, and smoke curtains only restrict the spread of smoke, and this is a very important difference.

At the moment if you are buying a smoke curtain within the UK, it should be CE marked to the European Standard; if you buy a fire curtain, there isnt actually a Standard to CE mark it to the moment. Both products basically are there to enhance architectural flexibility and they do form important parts of the buildings fire safety strategy, so it is important that they are applied properly and maintained properly once they are in place.

See www.coltinfo.co.uk and http://www.coltinfo.co.uk/fire-and-smoke-curtains-cpd-seminar.html for further information.

whitepaper - design considerations when integrating smoke and fire curtains

Documents