Coating fire resistance: Standard UNE-EN ISO 11925

Some works require a certain fire resistance to guarantee a specific behavior in case of fire. That is why the standard ISO 11925 standardizes this variable

Certain works carried out in the industrial sector are developed under a specific standardization framework that offers a series of guarantees in relation to certain aspects of particular relevance. Thanks to this, it is possible to precisely guarantee a certain performance and durability of the work carried out in the face of certain external agents.

Under these premises, some works in the industrial sector require a certain fire resistance to guarantee a specific behavior in case of fire. That is why the standard ISO 11925 standardizes this variable in order to be able to guarantee any work carried out under its indications. However, do you really know the content of this standard, do you know how important it is, and when it is necessary to use it? Don’t worry, because below we will show you the most relevant aspects of the very important standard UNE-EN ISO 11925.

Study of Standard UNE-EN ISO 11925.

The standard UNE-EN ISO 11925 establishes the criteria to be considered to objectively define the reaction of a given material to a heat source. More specifically, its purpose is to establish the resistance of a given material when directly exposed to an open flame.

To ensure that the result is reliable and equal for any of the materials tested, the ISO standard establishes the type of test to which the material must be subjected. This involves placing upright a flat object of 250 x 90 mm, with a maximum thickness of 60 mm per specimen, which has been conveniently coated with the material to be tested, inside a perfectly sized combustion chamber, made of stainless steel and equipped with the corresponding openings and supports for placement and observation. The heat source is supplied by a propane gas burner which is placed at an angle of 45º in respect to the object being tested.

With this equipment and set-up, 2 different tests are carried out in three different time ranges, so that between 6 and 18 samples are obtained for each test and time range. For each sample, factors typical of exposure to an intense heat source are analyzed, such as the characteristics of the residual particles generated by combustion, the propagation of the flame or the thermally affected area, among others. Subsequently, all these data and samples are analyzed separately in order to weight the results obtained and establish a certain degree of fire resistance.

The 2 tests performed are as follows:

  • Surface fire resistance, i.e., on the flat side of the object. The test is carried out by applying the flame 40 mm above the lower edge during the three established time ranges.
  • Perimeter fire resistance, i.e. at its edges. In this case, the test performed depends on the thickness of the object, so that the heat source is applied depending on whether the object is less than 3 mm, greater than 3 mm or greater than 9 mm.

Why is it important for a coating to be fire resistant?

A multitude of products are coated to beautify them and make them more attractive. However, the paints used are usually flammable, a fact that exponentially multiplies the devastating effects of any fire. For this reason, it is essential that in certain areas and sectors coatings are used to control the progress and consequences of a fire, thus constituting a form of passive protection against fire.

These types of coatings are known as intumescent flame-retardant paints and are generally designed to protect a specific substrate (wood, metal, etc.). Regardless of this, with the use of these coatings, these two great advantages are obtained:

  • Greater control of the variables inherent to a fire, such as fire prevention, flame propagation and self-extinguishing capacity. Thanks to all this, it is possible to reduce the virulence of the fire and with it the material and personal damages that it usually entails. For example, fire damage can be significantly reduced in a house or building where the furnishings are coated with fire-resistant paint.
  • The integrity of construction elements with a structural function is safeguarded, preventing materials from losing their mechanical properties. An example of this would be the steel structure used in a bridge or a building, which is prepared to absorb the oscillations typical of these constructions. In case of fire, if the coating used is not fire resistant, the steel quickly exceeds 500ºC, which causes it to lose bending capacity, making the material more rigid and prone to cracking and fissures. With the use of fire-resistant coatings, this serious problem disappears.

This particular behavior is achieved thanks to the use of specific chemical compounds. An example of this type of paint is Disolac’s PUR 840, a coating that, in addition to its flame-retardant properties, has direct adhesion to metals and a strong anti-corrosive power.

Damage reduction with fire-resistant paints tested according to standard UNE-EN ISO 11925

In certain areas or sectors, the consequences of a fire can be lethal and far-reaching. For this reason, under the guidelines of the standard UNE-EN ISO 11925, it is possible to submit any coating to a standardized fire resistance test, in order to market paints that provide passive fire prevention. With this, it is possible to reduce material and personal damages, establishing safer environments.

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