As a supplier of these products we often come across specifications that just don’t seem quite right……… so here are some of the questions that we find ourselves asking specifiers.
Think of curtains as a sail. When they restrict the opening, any air flow will increase in speed to travel through the reduced opening.
Smoke curtains don’t have side guides (unless specified), so will billow out of the wind path. Your smoke flow modelling will have to take this deflection into consideration. The lower the curtain descends, the greater the impact.
Fire curtains will have side guides but are not designed to cope with wind loads.
The curtain may be some distance from the final exit, but consider the impact of open exterior doors during the evacuation. Will airflow become channelled through the building?
BS EN 12101 Smoke and heat control systems Part 1: Specification for smoke barriers, provides some guidance on determining the effect of air flow on curtains.
The ‘Sm’ designation (as in -/*/*Sm) specified for smoke control doors in the Building Code assumes, when modelling, that these have zero leakage, except for a 10mm sill gap. Smoke and fire curtains do not provide this, as they have perimeter gaps, but the air leakage can be calculated, and can be included in your modelling. BS EN 12101 5.5.2 note 2 states that the system designer, when calculating for a specific installation, should take containment efficiency (smoke leakage) into consideration.
MBIE Commentary for Acceptable Solutions C/AS1 to C/AS7 mentions smoke curtains in 4.16.1 Closures in fire and smoke separations, but in 4.5.1 states that these must be ‘completely sealed’. The Acceptable Solutions define smoke separations as complying with BS EN 12101 Part 1, Specifications for smoke barriers (which includes fixed barriers), or being a ‘rigid element’, and forming an ‘imperforate barrier’. It does not specify a generic acceptable air leakage rate. BS EN 12101.1 includes note 4.1 that states… compliance, by itself, does not ensure fitness for purpose for an application.
Conventional fire curtains do not provide insulation in the traditional sense, partly because the required test thermocouples will not adhere to the curtain. In some BS EN tests irradiance is measured and this data can be used by the Fire Engineer to calculate the impact of radiant heat at given distances. (insulating zone).
Standard Smoke curtains will not provide ‘smoke control’, however there are specialised units for this type of application. These will require more detailed analysis of their capabilities by the Fire Engineer.
In New Zealand, as a general rule, BS, BS EN or AS Standards rather than UL (unless egress options are required). The relevant Standard(s) should be determined by the Fire Engineer.
European suppliers of these products have well developed testing regimes, including the following, amongst others-
BS EN 12101. Reliability & response, pressurised air leakage, and integrity
BS 476 Part 6 & 7. Fire propagation and surface spread of flame
BS EN 1634-3. Pressurised air leakage system test
BS 7346. Fire resistance, deflection, oversize, overlapping barrels.
AS 1530.4. Fire resistance tests.
ICC ACC77 Smoke containment for elevator doors
BS 8524.1 Specification for Fire Curtains.
Refer to the BLE link on our website for more details.
Curtains are often in hard to access and concealed locations. Regular operation, and access to ceiling voids for maintenance may be required.
Will the tester have visual control of the opening from the control panel?
How will you identify that obstructions such as desks and chairs are not to be placed in the path of the curtain?
It is not possible to fire test an opening in a fire wall unless it has a door in place, so opening designs tend to be developed by the curtain supplier rather than the wall supplier.
Due to the flexible nature and relatively light weight of Fire Curtains, most wall types are suitable, but check first.
Note: avoid timber architraves or combustible linings and sills.
The supplier can produce a PS3 (in their own format) but are unlikely to state compliance with the Building Code, just with the specified Test Standards. After all, they don’t produce the specification so can’t be responsible for its compliance with the Code.