Smoke and fire curtains webinar Q&A

Posted by Paul Compton on 03/03/15 11:30

NZ_Carmel_College_smoke_curtainAt our recent webinar on smoke and fire curtains, I received a large number of excellent questions during the Q&A section. Here you can see my answers to these questions, slightly edited for clarity. 

There is also a recording of the webinar available. Watching the recorded version will still enable you to claim CPD points.

Are there any requirements in Europe for a curtain to have a sensing edge to stop the curtain on contact with an obstruction?

There is no requirement in the UK, but this can be an option. I can’t speak for the rest of Europe, but I don’t know of any such requirement.

What is the minimum fire rating available for fire curtains? Is there a price difference depending on the rating?

This depends on the testing that the manufacturer has done. Although the minimum time given in EN13501-2 is 15 minutes, most are tested to at least 2 hours, though longer is possible. For Colt fire curtains there is a price increase above 60 minute fire rating as a more expensive strengthened fabric has to be used.

Are overlapped fire curtains allowed according to EN 16034?

Yes. The test Standard allows a test on an overlapped curtain, but you then need to specify a curtain that has been tested with an overlap. (An EXAP (extended field of application standard) is currently being finalised which will clarify the requirements.)

Which is better - gravity or drive down?

Gravity is the simplest system: there are no issues about fire rated cables and there is no need to protect any battery back-up system, since we know such curtains will always drop without power. Drive down systems are used in special situations, such as when you have multiple drops (although some gravity systems can also do this), or if curtain is not vertical e.g. horizontal or at an angle.

Once the specification has been established, are there any reasons why the cheapest curtain should not be selected? 

Taking for example a smoke curtain, if the product in question is CE marked and complies with the Standard, then there is little to tell you if the product will be good or bad, as CE marking is not a quality mark. There are a lot of differences in the products offered on the market, and the differences are in the detail. If you look at my slide on construction of products, you can see that they all have similar components, but the details with regards to reliability, ease of access etc. will differ. There is no easy way to ensure that you will get a good quality curtain other than to go to a reputable manufacturer.

On new build projects, which 'work package' normally includes smoke and fire curtains? 

Smoke curtains are generally within the smoke control package. With fire curtains it depends; they could be in a variety of packages e.g. in the electrical package.

Are curtains in Europe mainly specified by architects or by fire engineers? 

Simple systems will generally be specified by architects. Fire engineers are generally involved when there are more complex issues.

What sort of pressure ratings are we looking at in sealing a room? 

Fire pressures can generally be 5-20 Pa, but with a mechanical system these can increase – e.g. when protecting a lobby to a stairwell these can be as high as 60 Pa. If properly designed, installed and commissioned and if deployed before high pressures are reached, curtains should be able to withstand these pressures adequately.

Do you think that 15 minutes delay for an alarm of obstruction to a fire curtain in a dwelling is sufficient?

This is a difficult issue. When we were writing BS 8524, we had to agree on a reasonable time interval. We don’t want the alarm to be raised simply because people stand and talk under a curtain but equally we don’t want goods stored there long term. 10-15 minutes seems a reasonable level of safety. The most dangerous period is when people are asleep and this is when there is least likelihood of anything being placed in the curtain operating zone.

What is the status of pushing these products into the Building Standards in Europe? 

In the UK a British Standard is established. I cannot speak for other countries. In terms of legislation, such as Building Regulations, the pace of change is generally quite slow as legislators tend to want new developments to become established before introducing them.

Which applies to fire curtains, EN 16034 or EN 1634?

The product Standard for fire doors is EN 16034, but EN 1634 is the fire test Standard; there is plenty of potential for a mix up.

How well does an overlapping fire curtain stop smoke leakage?

Normally pretty well: since they are usually quite wide, overlaps are generally more air-tight than the side guides and the headbox of a curtain.

Can you discuss if/ how an escapee can pass through a curtain if it is lowered? 

Generally an escapee will use an egress control system but it is possible that this is not provided because the curtain is not covering a designated escape route. With overlapping curtains it is possible to push these aside or lift the bottom bar, but if it is a wide curtain with a heavy bottom bar then this will be difficult. Colt have built a smoke curtain with a split bottom bar to facilitate escape through the curtain, but this would require a fire engineered approach.

Is there such a product called fire cum smoke curtain?

A fire curtain is generally as good or better than a smoke curtain for smoke control, especially if a smoke sealed version is specified.  I think I mentioned that it is quite possible for a fire curtain to have a dual drop facility to initially drop part way to act a smoke curtain and then to drop fully as a fire curtain as well.

Are there any third party accreditation schemes that cover the installers, designers and service engineers for fire and smoke curtains? 

There is a general certification scheme for designers of smoke control systems in the UK but nothing for fire curtains. At the time of writing BS 8524, there was a discussion about this, but there is currently no scheme.

Is the European certification regime similar to that required by NFPA? 

There are UL standards for draught (smoke) curtains and fire curtains, but they are different to EN 12101-1 and BS 8524. With NFPA 92 and 204 there is a requirement for “listing” but this may be to UL or to any equivalent acceptable in the jurisdiction where the product is being used. In Annex A of the standards, EN 12101 is referred to as a suitable certification scheme.

How are horizontal curtains utilised in Europe?

They are generally used where there is a fire engineering need to fill a void between two storeys. A fire curtain would be used if the floor is a compartment floor, otherwise a smoke curtain would be sufficient.

What amount of smoke leakage occurs around the edges of a fire curtain, and would the curtain meet the designation of S for fire doors in the Building Regulations? 

The maximum leakage for a smoke sealed fire curtain is set out in BS 8524, equivalent to a fire door in the same application. A smoke sealed fire curtain usually has has seals or rubbing surfaced in the headbox and side guides.

Will it damage the fire/smoke drop curtain if you manually lift the curtain, for example if people escape and just lift the curtain and crawl under it? 

Generally no, but the curtain could be crumpled and not drop fully again, which could cause some reduction in the amount of protection. It is best to raise the curtain using the controls in the normal manner.

What should activate a fire curtain? Heat detectors?  If so, at what heat should it operate the fire curtain and how far away from the curtain should it be located? 

A table in BS 8524-2 lists which activation methods are suitable. If a heat detector is used it should be at high level, close to the curtain.

Is there any solution to design out unsightly side guides with fire curtains, e.g. when you have  glass ballustrades, so that an open plan arrangement can be maintained? 

I am afraid that there is no option – you need side guides at the ends of each run of curtain, unless you have a system designed as a concertina which can be made to go round corners.

Provided that smoke and fire curtains are not mentioned in the building legislation, does that mean that every design is subject to an "alternative solution"? 

Such curtains are indeed not mentioned in the Building Regulations. This means that every curtain needs a special or fire engineered approach, and equivalent performance to ADB has to be proven. If you have a product complying with BS 8524, then this helps.

When being used in front of a lift, is there any issue with egress should the curtain be dropped?  Is the curtain easy to lift by hand? 

It is not the usual practice to site a fire curtain in front of alift door if that lift will be used for evacuation of fire fighting in case of emergency. The bottom bar can be lifted to assist escape but this is not ideal.

Are there any requirements in the EN testing for impact testing?  Either some sort of weighted bag or hose stream test? 

There is in BS 8524 but not in EN 16034. A weighted bag test is used.

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Paul Compton Paul Compton is Technical Director for Colt, experienced in smoke control, HVAC, solar shading and louvre systems.

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Topics: Fire Containment, Smoke Containment, Webinar, Curtains