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Proyectos Cottés Group

Verifications for dimensional extrapolation of Fire Curtains

8 julio, 2013
Figura1. Sistema con 3 rodillos (2 Solapes)

At present the fire curtains are gaining importance in the fire protection market because this kind of systems offer a great flexibility to adapt to the needs of the projects: its lightness, the ability to create invisible screens for the fire sectorization (the system is retracted to the container boxes until be activated by an alarm signal) and the guarantee of high degrees of resistance and insulation to the fire ,  offers an aesthetic and functional solution highly demanded by architectural studies for the open concept of  spaces.

There is currently no standardized rules specific to the product, it is tested based on the UNE EN 1634-1 (Fire resistance tests for doors, shutters and openable windows). This standard, in most cases, is applicable to rigid elements that could be static or mobile, such as fire doors, shutters, guillotines doors, etc., But in our case, we are talking about textile systems that offer greater flexibility and behave differently to the pressures generated by the hot gases in the event of a fire. Therefore, to justify the higher dimensions to the tested dimensions, is necessary to evaluate certain requirements based on the draft standard Pr-EN 15269-11.

Within all the verifications and evaluate conditions, we highlight the following order of importance:

1. Systems with multiple rollers or multiple overlaps

All systems that to increase their width dimension requiring the use of multiple superimposed rollers creating overlaps in the system, must be tested with the most unfavorable configuration. That is, if we need 3 rollers to reach a certain size, the system shall be tested with 2 overlaps and so on. Fig1.

Figura1. Sistema con 3 rodillos (2 Solapes)

Figure 1. System with 3 rollers (2 Overlaps)

The testing of this system must to be done with the counterweight bar in the final position (touching the floor) and you can not be used a counterweight bar more heavy, leaving a distance from the ground to justify the resistance of the fabric, because if the counterweight does not touch the floor, the overlaps would remain tensioned and therefore the barrier will be completely closed. If the counterweight bar rests on the ground, the fabric will not be tensioned and the overlaps may be opened due to the movement thereof by the pressure differences in the fire test. Fig2. Integrity failure by opening that allows the passage of  a bar gauge of 25 mm diameter (Fire Test failure).

Fig2. Sistema con 3 rodillos (2 solapes) Apertura que permite paso de galga 25 mm (fallo integridad)

Figure 2. Integrity failure by opening that allows the passage of  a bar gauge of 25 mm diameter (Fire Test failure).

The dimension of the overlaps must be calculated according to the height of the barrier, taking into account the deflection of the fabric in fire test and the dimension of the overlaps in the tested system. Due to the sail effect of the fabric produced with the pressure in case of fire, the overlaps if not be calculated well could be opened.

If we tested, for example, a barrier of dimensions 2880 x 3000h, with an overlap of 600 mm wide and 150 mm deflection, to obtain the extrapolation to a 4000 x 4000h curtain we should use an overlap of 800 mm (Calculation using  Pr-EN 15269-11).

2. Classification type required

Depending on the searched classification for  the system, we should perform the following checks:

Clasification E (System Integrity): This clasification only check the fire resistance of the system. To justify the extrapolation on this classification, we need to perform stress tests of the fabric to verify:

  • Extrapolation on height: An extra weight is added to the system in its vertical position to justify the weight of the fabric that we would use for dimensions larger than those tested.
  • Extrapolation on width: An extra weight is added to the system in its horizontal position to justify the stresses exerted by the furnace pressure due the sail effect on the fabric, in this test we will verify the resistance of the fabric fixed to their side guides and the joining seams.

Fig.3 Rotura de costura por tensión excesiva

Fig.3. Counterweight Deflection

Classification EI (Integrity and Insulation): In addition to all the above, it has to verify the thermal insulation system, which may not exceed 180 ° C maximum temperature at any point on the system or an average of 140 ° C on the installed thermocouples. If the system is equipped with sprinklers that projected water onto the fabric, we has to verify that with the maximum dimension of the system (extrapolated dimension), the water spray is done in a uniform, with the same pressure and flow rate in the tested sample. May not be dry points or parts with lowest water spray.

Classification EW (Integrity and Low Radiation): In addition to the above, we have to verify the radiation emitted by the system which in no case could exceed 15 kW/m2 to a meter away. For higher dimensions, we need to be based on the radiation calculations obtained according to standard EN15254-4:2008 which calculates the increase in radiation based on the increase in sample size. One system of dimensions 3000 x 3000h which obtained a EW-60 classification, at 60 minutes the system exceeded 15 kW/m2, for the same system of dimensions 12000 x 3000h at the same minute, the radiation would be 21 kW/m2, outside the norm.

3. Counterweights

The counterweight bars, usually are rigid metal elements, which upon contact with fire, reacts dilating or deform. In this sense, we have to assess the magnitude of the gaps between the counterweight bar and side guides before and after the test.

For example, if the counterweight bar is formed by standard steel, we have one dilatation of 5 mm per linear meter of counterweight, for one system of 3000mm wide, we would need 15 -20 mm of gaps between the counterweight bar and side guides. Following this approach, for a system of 12000mm wide, would need a gap of 60 mm.

Without these gaps, the deflection of the counterweight would cause failure of the system integrity.

Fig3b. Deflexión contrapeso

Fig.3b. Counterweight Deflection

 Fig4. Deflexión de barra contrapeso (Fallo integridad)

Fig.4. Counterweight Deflection (Integrity Failure)

4. Durability and system use

It has to perform a fatigue test of the entire system, the test is a funcional test of all components. It will verify the durability of the system with the dimensions on the fire test and with the maximum dimension. The textiles systems, when coiling on their axes, can cause creases or wrinkles that deriving on wear and tear the fabric or seams due the error repeatability on the funcional test. For this reason should be justified durability of the system as a range of dimensions.

5. Report technical approval

In the absence of a harmonized standard for this type of systems, the validation of these methods requires report system technical approvals issued by an accredited laboratory. The suitability report must collect data on product dimensions, in addition to the conditions of the system tested, and the necessary modifications (if necessary) to achieve the maximum dimensions. If this does not appear in that report should be requested from the manufacturer of the product.

 Raúl Alonso

Product Manager  Cottés Group – Tecnitex

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