Insufficiently regulated in much of the world, the fire resistance of glass is an important issue that is often poorly resolved, endangering people's lives. What characteristics must a glass have to resist a fire? What options are there to choose from? We talked with the experts of Cristales Dialum to investigate these essential questions.
Leading the way in building fire protection, Europe has developed comprehensive standards for safety, incorporating products and solutions that other areas are not even aware of. Its specifications place special emphasis on the fact that fire response should be considered an integral part of glass production, and that the glass may not be effective if it is not accompanied by a suitable framework. As for the glass itself, there are two main types of products specified:
E-Class Fire Resistant Glass: Integrity
In the case of a fire, the E-class fire-resistant glass stops the propagation of flames into adjoining spaces, and significantly also prevents the smoke and toxic gases that emanate from burning materials, furniture, and objects from reaching other spaces. Smoke and its toxicity is the leading cause of death in a fire: for example, the burning of wood and PVC generates carbon monoxide, while the combustion of plastics, resins, and nylon, releases cyanide, two of the most dangerous toxic agents for humans.
To ensure maximum safety, the E-class glass could maintain its integrity for up to 120 minutes, resisting the temperature rises on the other side. Its transparency should not be completely lost, ensuring a certain level of visibility in case of evacuation.
However, this type of glass lets in a high percentage of heat, so it should be used in areas where this increase does not pose a real danger to its occupants. Although its price is affordable, and it does remain a viable option preferable to glass without any protection, it is necessary to consider that its temperature will increase in a matter of minutes and that it can be dangerous in case of evacuation in the dark.
EI-Class Fire Resistant Glass: Integrity + Insulation
The EI-Class fire-resistant glass not only fulfills all the functions of the E-Class but also almost completely prevents the passage of temperature into the adjoining space, functioning as a barrier that absorbs the heat generated from the fire and inhibits its spread. In the case of a dark evacuation, people could even lean on the glass and not burn, effectively escaping. Its composition includes a transparent protective layer with intumescent properties, which forms an anti-thermal shield when faced with a temperature above 100ºC. The more layers included, the greater the resistance time.
To test it, the glass and frame assembly is exposed to a heat of 1200 degrees. In addition to integrity and temperature, aspects such as the emission of flammable gases and smoke leaks are analyzed. The tested element must remain intact and not transmit heat from the opposite side for 30, 60, 90, or 120 minutes, to achieve the classification F30, F60, F90, or F120, respectively.
What should be taken into account when choosing?
The most important step is to define if the glass should be class E or EI, according to the parameters set forth above. However, there are a number of other relevant points that should be considered:
- Know the fire protection requirement. The project, the position of the glass cloth, the fuel load of the building, and factors such as operation, time, and evacuation routes, among other related aspects, should be studied.
- Understand if the glazed element fulfills some additional function. Normally, fire-resistant elements not only insulate from fire but also fulfill functions such as allowing access and evacuation to buildings, even being able to block or open remotely. All these functions and special features could change the design of the element.
- Know the location of the glass. Glass located outside, or that can receive solar radiation, should be protected to prevent UV radiation from damaging it over time. For this, variants of the same glass with UV filters are used.
- Integrate the flame arresters and firewall elements in the architecture. The high degree of technical sophistication of fire-resistant glass and carpentry allows the elements to be perfectly integrated into current projects. The aesthetics, dimensions, shapes, and frames are identical to those used in 'unprotected' glazed elements, being invisible to the user but equally effective.
As mentioned previously, any solution chosen must incorporate frames that support the resistance delivered by the glass. It is not effective to choose a very resistant glass if your frames will lose their integrity quickly; the entire wall may fall even if the glass remains intact. In the face of a fire, the entire system must behave comprehensively, and support each other.
In addition, fire-resistant glazed elements also have to be operational, resistant, and functional on a day-to-day basis. It is likely that a glazed fire door will not have to contain a fire at any point in its life, yet it could open more than 30 times in a single day. High rigidity steel profiles are an excellent ally for all these effects.
The design of protected areas against eventual fires is essential in any architectural project, especially in public and mass-use buildings. Therefore, the proper use of glazed systems can be instrumental when allowing the proper evacuation of interior spaces, possibly marking the difference between the life and death for many.
Review a guide for choosing glass in architectural projects.