Fire Resistance - Fire Safety
In a building, fire barriers often have to be present. Fire barriers are then intended to make safe evacuation possible or to restrict the extent of any fire. Whether and where fire barriers are needed is down to the Building Regulation. The required quality of the fire barrier is also down to the Building Regulation, in which the requirement is dependent on various aspects. So, for example, the building height is also decisive in the question as to whether a fire barrier must be fire resistant for 30 or 60 minutes
In EN regulations, four criteria are differentiated, on the basis of which the fire resistance may be determined. The results of a fire resistance investigation (‘fire test’) is translated into these criteria:
This criterion is applicable to load-bearing structures, in which the structure must be able to support more load than its own weight;
This looks into holes and ruptures that arise in the structure during a fire test (determined with gauges which can be inserted into the furnace), or there may be hot gases that go through the structure (smouldering or burning of 'padded cushions'), and whether flames arise during the fire test on the non-heated side;
In this criterion, the average surface temperature on the non-heated side (so the ‘safe’ side) during a fire test must not increase by more than 140 degrees. Locally, an increase to 180 degrees is permissible;
The thermal radiation emitted during a fire test may not be more than 15 kW/m2, measured at 1 m distance in the centre of the testpiece.
Depending on the situation, one or more criteria may be set as the requirement. Which criteria must be satisfied is determined in the Natioan Building regulation. The flame resistance seems significant in all cases, the buckling criterion is not relevant for structures that do not support any load. So this criterion is not relevant to NOFISOL® products.
As well as the fire-resistance function of materials or components, fire safety is also a crucial factor in specifying building materials.
This not only relates to material properties (thinking of smoke formation through the material itself) but also to the smoke-resistance of the material.
On the basis of NEN 6075:2011, the smoke resistance of materials is established. In so doing, the following are used as the basis:
Smoke Penetration Resistance (SPR)
This is obtained by multiplying the fire resistance obtained in relation to the ‘flame resistance’ criterion of the relevant cavity barrier by a factor of 1.5;
If the fire resistance mentioned in the previous point is greater than 20 minutes (E 20), then the relevant component according to NEN 6075:2011 is assigned a smoke leakage rate Sa;
If the fire resistance mentioned in the first point above is greater than 30 minutes (E 30), then the relevant component may be assigned a smoke leakage rate Sm;
If a smoke leakage rate Sm is assigned to a cavity barrier, then the relevant cavity barrier may also be assigned a smoke leakage rate Sa.
The fire classes that are required in the Building Regulation are the European fire propagation classification as mentioned in NEN-EN 13501-1, in the ‘Classification Criteria for Construction Products’ section. European classifications run from A1 to F, in which A1 indicates the highest classification and F the lowest. The classification A1 to F relates to a classification based on thermal capacity, heat content, ignition and flame spread of the material. Furthermore, there is also a separate classification for the smoke production and the burning droplets and particles.
Materials in this class do not contribute to every stage of the fire, not even with a completely-developed fire.
Materials in this class do not contribute to a completely-developed fire with the fire load and spread of the fire. Practically incombustible.
Possible combustible materials that provide a limited contribution to the risk of fire.
Materials in this classification show a limited lateral spread of fire when they are exposed to the heat of flames (‘single burning item’). Combustible materials that contribute to the risk of fire.
Materials in this class provide longer resistance to small flame contact without substantial spread of fire occurring as a result. In so doing, they are also exposed to the heat of flames that arises with sufficiently delayed and limited dissipation of heat. Combustible materials that make a major contribution to the risk of fire.
Materials in this class make a very high contribution to the fire. The materials are resistant to fire for a short period without considerable spread of flames. Very easily combustible materials that make a very high contribution to the risk of fire.
Materials for which no response to fire propagation requirements has been determined. Extremely flammable materials.
The smoke classes that are required in the Building Regulation are the European smoke classes as mentioned in NEN-EN 13501-1, in the ‘Additional Classifications for Smoke Production’ section. The European classifications go from S1 to S3;
S1 - Low smoke production.
S2 - The total emission of smoke and the increase in smoke production are limited.
S3 - No restriction to smoke production required.
Met druppelvorming worden brandende of gloeiende hete druppels bedoeld. Er zijn Europese klassen, onderverdeeld in d0 tot en met d2.
By droplet-forming, burning or smouldering, hot droplets are meant. There are European classifications, subdivided into d0 to d2.
d0 - No flaming droplets / particles.
d1 - No flaming droplets / particles for longer than 10 seconds.
d2 - No restriction.