Annex D (normative) Test method for barrier assembly reliability and response time and the durability of materials

Whilst this annex states that the barrier assembly must be tested for its reliability and response time using the control system with which it is intended to be used to modify its speed, there are no publicly available details of what was tested meaning you have to buy on trust that you are getting what was tested. This is one of the critical shortcomings of BS 8524 and its paperwork and one we all hope will be rectified when it is revised.

This issue is compounded by BS 8524 losing Notified Body support on 9th June 2023 meaning there is now also no valid third-party certification available for it. You can read more about how important this is for risk in the Adexon article⁶. The annexe also requires the specimen to be tested in the orientation intended by the manufacturer. The downside to this is that there is no publicly available documentation to tell the consumer what this orientation is, so it could be installed on-site the wrong way around meaning it sits with its untested side to the fire. This is another very dangerous deficiency with the BS 8524 paperwork.

The reliability and durability testing should simulate the usage of the curtain, with the required 500 cycles representing one test each week for 10 years. This cycle test is not unique to BS 8524 (the same cycle test requirement is in both the other standards) and whilst it is good if the exact same curtain fabric is cycle tested and then fire tested, this has limited benefit if only part of the curtain fabric that was cycle tested is used in the fire test. If the exact same piece and size of fabric is fire tested it would point to the fabric still providing a fire barrier after years of use – if it was installed as well as it was for the test, and subject to it not incurring one of the frequent headaches the old designs used for BS 8524 fire curtains are susceptible to. Watch this short video to see the difference between the old designs and the newer designs; the newer designs are tested to BS EN 16034 and ISO 21524⁴.

Similar to BS EN 1192, Annex D requires the barrier assembly to be tested for impact. This simulates a body colliding or falling into the closed curtain, which is especially important when the curtain is used along an escape route. A 50kg soft weight is dropped against the face of the curtain (at two different heights) with an impact energy of 100Nm prior to cycling the curtain for 500 operations. At the end of cycling, the curtain is subjected to the impact test again and the curtain is checked for damage. Whilst this is a helpful test in theory, when we see what happens to curtains that have passed this test it raises questions as to the value of the testing criteria, and points to making a design-led decision instead. You can read more about the two most common designs on the market⁷.

Annex E (normative) Test method for motors

The motor reliability and durability testing has little safety benefit as fire curtains tested to any of these standards have to deploy under gravity (without the motor working). The motor is tested to lift a weight equating to 90% of the maximum load, over a distance of 3m before it is released. There is a universal classification given to the number of cycles attained: C1 for 500 cycles, C2 for 10,000 cycles, C3 for 50,000 cycles.

Annex G (normative) Test method for the reliability of motor operation at elevated temperatures.

This test is carried out by placing a motor specimen in a furnace and operating it at maximum load following a prescribed timeline heat curve for a specified number of cycles. Elevated temperature testing of motors provides evidence that the motor will continue to function during the start of a fire, allowing the fire curtain to be retracted to release anyone trapped or for the Fire and Rescue Service to pass under the curtain. In theory, this could be seen as a good test, as it demonstrates the robustness of the curtain’s control mechanism, even under extreme conditions.

However, in practice, a fire curtain should never be operable if there are temperatures of anything approaching the upper limit tested of 400°C on one side, as this would pose a severe-to-fatal risk to the operator and could allow the fire to pass beyond the designated compartmentation barrier and thus endanger the whole building. You can read more about this in the technical comparison white paper already referred to, and this article, The dangers of the hot motor test in BS 8524-1:2013¹⁸

The other remaining annexes include:

• Annex A (normative) Overlapping multiple barriers. This explains that the values for the minimum width of the end curtain and the minimum width of the overlap are calculated based on values recorded during the fire test. We believe it is important for the consumer to be able to check the amount of overlap tested and that this is related to the height (drop) of the fire curtain. It is obvious that a higher curtain would require more overlap. For example, 1m of overlap may suffice for a 2.2mH fire curtain but it is highly unlikely it would suffice on a 10mH fire curtain. This critical information is not available under BS 8524.
• Annex B (normative) Order of testing. This defines the order of testing for each specimen.
• Annex C (normative) General requirements for testing. This includes dimensions, fixing methods, joints and seams etc. Unfortunately, little to none of this information is displayed in the publicly available documentation leaving it to the manufacturers to disclose what they feel best.
• Annex F (normative) Calculation of ambient temperature smoke leakage. For more in-depth information about smoke testing, read ‘The science behind cold smoke seals’⁸ and ‘Are cold smoke seals in a fire a cause for concern?’⁹.
• Annex H (normative) Test method for ancillary and optional equipment
• Annex I (informative) Typical product performance summary

The annexes and test methods are all intended to show the performance of the product in use and are largely relevant to its application. For an in-depth look at BS 8524, read the Adexon Fire & Smoke Curtains white paper².

Part 2 of BS 8524 is a code of practice for the common applications, installation, commissioning and servicing of the product. There are specified requirements for installation although these are not comprehensive. This code of practice and the paperwork is not the whole answer. With or without this code of practice it is a legal requirement of the Regulatory Reform (Fire Safety) Order 2005 that life-safety products such as fire curtains “are subject to a suitable system of maintenance and are maintained in an efficient state, in efficient working order and in good repair” and this is critically more important than any code of practice, however well-intentioned. As above, if the product doesn’t work when tested (which we find a lot of the time with certain older designs still in use) then it isn’t fit-for-purpose in its current state and needs urgent looking at by a specialist, or the Responsible Person is breaching the legal requirements of the Regulatory Reform (Fire Safety) Order 2005.

The installation as outlined in BS 8524-2, along with other fire curtain standards, can be third-party checked and approved under schemes such as IFCC’s SDI05 installer scheme. This scheme does not check the manufacture of the product so should only be used as the ‘icing on the cake’ once you have a fire curtain manufactured under a valid third-party certification scheme. These bodies will regularly audit installations to ensure competency and that the products installed are as required.

Part 2 also recommends a series of regular checks although these should already be in the Operation & Maintenance Manual provided by the manufacturer to enable compliance with the Regulatory Reform (Fire Safety) Order 2005. These will include what should be done regularly on site, and those actions that are less frequent and must be undertaken by a competent engineer.

BS 8524 advises checking for obstructions that might prevent the curtain from deploying, such as alterations to cosmetic finishes, lighting, shelving or racking, furniture or temporary displays. However, possibly the biggest danger with obstructions preventing deployment is within the design used for BS 8524 fire curtains themselves. The older designs used on BS 8524 fire curtains use a smoke seal or rubber draft excluder to provide smoke control. These are prone to becoming detached and blocking the side guide. See this case-in-point³.

It also recommends that the curtain should be operated at least monthly, and on escape routes weekly. Adexon advocates all fire curtains are tested weekly which is above and beyond BS 8524 but deemed necessary for life-safety equipment. BS 8524 stipulates that if it forms part of a smoke control system protecting a means of escape, the barrier assembly should be operated in conjunction with the smoke control system.

As per user instruction in the product’s Operation & Maintenance Manual provided by the manufacturer, there should be weekly tests of self-closing devices and automatic release mechanisms via a test switch. They should also check that the sensory detection equipment and self-test facility are functioning correctly.

Without valid third-party certification, BS 8524 loses its mainstay selling point that periodic audits by a Notified Body ensure the product’s components are the same as those that were tested originally.

Current fire curtain standards

ISO 21524 is an international standard for fire curtains that some say is the long-term future. However, like BS 8524, it is not harmonised so cannot be used for vertical fire curtains in the UK or EU markets meaning it is limited to horizontal fire curtains currently (concertina fire curtains have certification schemes under BS EN 16034 already).

Unfortunately, ISO 21524 includes new features of questionable value and safety such as pass doors and vision panels. Neither feature makes sense practically or for safety.

The pass door has a number of issues ranging from the trip hazard threshold (bottom bar) to the problem that occurs with the reality of someone fighting with the Velcro in a fire escape situation when it is much simpler to use the ERB (emergency retract button). ERBs will retract the curtain for a preset time – if it is safe to do so. There is no way to stop someone from opening a Velcro pass door if there is a fire on the other side which could be very dangerous or even fatal to the user and endanger the whole building. Conversely, an ERB can be micro-switched to thermal and smoke sensors that prevent activation if either is present on the other side of the curtain.

The vision panels are also of negligible value in a fire when rooms are filled with smoke. Thermal and smoke sensors can advise the fire services centrally as to the presence of smoke and/or fire, and it is negligent to recommend that a room sweep check for people needing to escape is done courtesy of a small grainy window in the fire curtain. If it is safe to enter then the ERB should be used to enable a thorough check before resealing the room.

ISO 21524 also introduces a new idea of repairing patches to tears in the fabric. This is not advisable as there is no third-party control over the quality of repair on site and we are talking about a life safety product that relies on the integrity of the curtain to perform and save lives. Additionally, this idea does not solve the root cause of tearing fabric and further tears will recur over time if the root cause is not resolved. It is akin to the analogy of using a sticky plaster on a broken arm. The root cause for fabric tearing in the vast majority of cases is an old design that is still in use by some manufacturers. This design uses bolts or poppers punctured through the edges of the fabric to retain the fabric in the side guides. This causes a weakness in the fabric which over time will lead to a tear under the strain of regular testing. It happens even more quickly when the bolts or poppers jam in the guides. The solution to these problems is found in new designs of fire curtains that will soon be the norm for all manufacturers. Adexon does not advocate temporary and unreliable fabric patching in the meantime. Read more about the new design that solves the root cause of fabric tears⁴.

If the revision of BS 8524-1 and BS 8524-2 include these novel and potentially unsafe or even dangerous features, Adexon will be recommending it goes back out for revision again. Life-safety is too important to shape standards around manufacturer’s products and instead, we manufacturers should up our game and lead the way in safety, with the standards simply providing the standardised benchmark.

Currently, the harmonised European Standard BS EN 16034 is the legal requirement to CE mark all vertical fire curtains to since 1st November 2019. As an improvement to BS 8524, BS EN 16034 only allows fire testing to BS EN 1634-1 as opposed to BS 476. BS 8524 has 30 references to BS 476 in it. See our article, ‘Why scrapping BS 476 is good for safety’¹⁰.

BS EN 16034 is harmonised and thus comes under the Construction Products Regulations. You can read full details on it in the Adexon white paper¹.

There is no ambiguity in the application of BS EN 16034 to fire curtains, even standing up to a challenge from those in favour of retaining BS 8524 back in 2018. You can see the details of this in this short video⁵.

It is misleading to say the foreword of BS EN 16034 standard says anything about BS 8524; it is the BSi’s National foreword that draws the reader’s attention to BS 8524. It is not part of the legally required harmonised standard. BSi adds ‘front’ and ‘back’ covers when they publish European Standards, sometimes referring to British Standards such as in this case, but always adding the disclaimer in bold, “Compliance with a British Standard cannot confer immunity from legal obligations”.

‘Legal obligations’ would include compliance with the CPR for construction products as evidenced by CE marking to the applicable harmonised standard, from a Notified Body. In the case of vertical fire curtains, this means CE marking to BS EN 16034. The Adexon white paper comprehensively goes over all the questions around BS 8524 and BS EN 16034 including applications of either¹.

You can also find an 8-minute video going over the reasons some have cited for continuing to use BS 8524¹¹.

Some supporters of BS 8524 have tried to cite that harmonised product standard BS EN 16034 is used in conjunction with BS EN 13241:2003 + A2:2016 and that the latter does not specifically refer to fire curtains. There are two points that demonstrate this is an invalid argument. The first is covered in this video⁵ where some in the UK tried to push back (rebut) BS EN 16034 applying to fire curtains. The Steering Group (GNB-CPR-SG06) set up for the standard considered the case and after deliberation reiterated that BS EN 16034 does cover fire curtains. This meant that when it became harmonised on 1st November 2019 it became a legal requirement to CE mark to it.

The second point is about applications. It is plainly written in the scope of the harmonised standard, BS EN 16034, that the scope includes vertical fire curtains. Here is an extract and the full discussion and review of this can be found in the fire curtain regulations white paper:

Scope (extract)

• pedestrian doorsets… etc…” and so on.

Definitions (extract):

• A “doorset” is defined as a whole range of items including “rolling shutter and/ or operable fabric curtains including any frame or guide” or “rolling or folding curtain”.
• An “operable fabric curtain” is defined as a “doorset with leaf constructed from woven material… which functions as a rolling shutter”.

For these reasons, we believe that citing ‘BS EN 13241 doesn’t refer specifically to fire curtains’ as a reason not to CE mark to BS EN 16034 is an example of dangerously misleading marketing for commercial gain. This behaviour has long been a source of ire and risk to the fire industry and Adexon feels a responsibility to provide the consumer with an in-depth analysis of such articles where it can, with accurate references to standards together with all relevant context so they are understood clearly for the sake of fire safety and legal compliance.

Those with a vested interest in BS 8524 may point to articles such as the Association for Specialist Fire Protection’s (ASFP’s), Technical Guidance Document (TGD) 21: UKCA / CE Marking of Operable Fabric Curtains¹², which recommends that manufacturers wishing to CE mark operable fabric curtains seek further independent legal advice. What we need to understand is the context of this document (and others similar) that some Trade Bodies are there to support their members. It will come as no surprise that ASFP’s largest fire curtains members are keen supporters of BS 8524. ASFP are very transparent about this support for their members, and it can be seen in various documents on fire curtains by the ASFP whose members still manufacture primarily to BS 8524.

Rather than blatantly deny the requirement for BS EN 16034, the tactic has instead been to create uncertainty.

Another area where this support for members can be seen is in ASFP’s defence of BS 476 which suits their members’ products, even now calling for an extension to the transition period after the Building Safety Act proposed a 12-month period. This is despite the fact that we have known in this country that the European Standards are superior and more thorough (safer) for over 20 years!

Adexon has produced a video going over all the common reasons supporters of BS 8524 give for continuing to use it. None of them stand up to scrutiny¹¹.

Prior to the Adexon white paper on fire curtain regulations, there had been over 30 articles, adverts and editorials published on fire curtains since BS EN 16034 became legally required on 1st November 2019. 30 of the articles refer to BS 8524 and not one of them referred to BS EN 16034. Since Adexon first published the white paper, those authors have started to acknowledge the existence of the legal requirement to CE mark to BS EN 16034 for the first time whilst attempting to ‘piggy-back’ the third-party certification of BS EN 16034 by saying BS 8524 and BS EN 16034 are ‘complimenting’ standards i.e. have them both. This is not the case, for example, BS 8524 allows BS 476 as an option for fire testing whilst BS EN 16034 insists on only using the superior European Standard BS EN 1634-1 fire testing.

Conclusion: Where does BS 8524 now sit in the UK market for fire curtains?

BS 8524 was the first product standard in the world to apply solely to active fire curtain barrier assemblies. Whilst this was a step in the right direction 10 years ago, BS 8524 no longer has valid third-party certification. No fire industry professional would advocate using a life-safety product without valid third-party certification, unless they had a vested interest in saying so. Additionally, since 1st November 2019, it has been a legal requirement of the Construction Products Regulations (CPR) to CE mark all vertical fire curtains to BS EN 16034. BS 8524 didn’t ever achieve harmonised status so cannot offer a route to legal compliance with the CPR. These two factors (legal compliance and third-party certification) mean BS 8524:

• should not be used for any vertical fire curtains since 1st November 2019 unless also CE marked to BS EN 16034*
• should not be used for any fire curtains (vertical or concertina or horizontal) since 9th June 2023 when the last valid third-party certification for BS 8524 expired.

You may have issues having BS 8524 as well as BS EN 16034 if e.g. the fire test is done to BS 476 which is allowed by BS 8524. BS 476 is prohibited by BS EN 16034 and the latter is the legally required product standard so is the one to go by where there is conflict.

BS 8524 is often over-sold with claims of all sorts of additional tests, and references to the installation code of practice. The reality is that a number of the ‘additional’ tests in BS 8524 are fads or even dangerous, and whilst the code of practice is a nice idea, the acid test for installation and commissioning is that the product works when it should i.e. the legal requirement of the Regulatory Reform (Fire Safety) Order 2005 that life-safety products such as fire curtains “are subject to a suitable system of maintenance and are maintained in an efficient state, in efficient working order and in good repair”. Unfortunately, BS 8524 products don’t always tick this box as can be seen with this case-in-point £1bn office development in central London for a large global bank³.

So will BS 8524 achieve valid third-party certification again?

We are told it will*. But when?  No one can say. No one would indemnify you against a date when third-party certification will be available again for BS 8524. What we do know is that there is an indefinite and lengthy process before valid third-party certification for BS 8524 may be available again:

• BS 8524 needs revising*
• Notified Bodies then need to create a scheme that can be assessed and accredited by UKAS or equivalent
• Manufacturers then need to pass the new tests in BS 8524 including the European Standards fire test
• Then certification, audits, lots of paperwork, and Factory Production Control needs to be completed

*If BS 476, and/ or the superfluous or even dangerous tests or recommendations are still in BS 8524, we would recommend staying away from it.

Even if and when BS 8524 achieves third-party certification again, it will still be a legal requirement to CE mark to BS EN 16034. The foreword of the actual harmonised standard states, This European Standard [BS EN 16034] shall be given the status of a national standard… and conflicting national standards shall be withdrawn at the latest by October 2019”. This won’t change until BS EN 16034 changes, the Construction Products Regulations change, or BS 8524 becomes harmonised. None of these are likely within the next five years, if ever (BS 8524 is highly unlikely to ever become harmonised).

With the over-selling of BS 8524 in mind, it is not surprising that built environment professionals have been caught up in using the standard.

In the meantime

Do not use BS 8524, at least until it has valid third-party certification again. Even then, insist on legal compliance with the CPR. In the meantime, insist on valid third-party certification, insist on legal compliance with the CPR, (and choose the best design).

About the author:

This white paper was written by the team at Adexon Fire & Smoke in August 2023. It includes the views of the Adexon team and its intention is to raise awareness and standards in the fire safety industry.

We are at the forefront of valid third-party certification and legal compliance for fire and smoke curtains.

We are the only company in the UK with third-party certification to a product standard (ISO 21524) for horizontal fire curtains.

We may be the only company in the UK to have a third-party certified concertina smoke curtain to DH60.

This year alone we have been invited to talk at a number of prestigious events such as

• The Fire Safety Event¹³
• Chartered Association of Building Engineers (CABE) Conference Series
  • • Cabe Salford – Built Environment England – Built Environment Series¹⁴
    • Cabe Cardiff – Built Environment Wales – Built Environment Series¹⁵
• Vision Construct 2023 | Royal Suite, Wembley Stadium | Construction conference and expo | Resibuild¹⁶
• Build2Perform/CABE at Excel in Dec¹⁷

We have invested significantly over recent years to not only develop the UK’s premier design of active fire curtain⁴ but also in testing and certification, such that we have the widest range of legally compliant and third-party certified fire curtains in the UK.

If you have a question for the team or would like to give feedback on this white paper or find out more, please get in touch.