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The Behavior of Industrial Insulation in Case of Fire
Blog in Brief
Industrial fires claim multiple lives and cost millions of dollars in direct and shut-down costs annually.1 Their prevention should be sought in all aspects of industrial design, including insulation. However, much confusion surrounds insulation material combustibility and toxicity. Misleading terminology based on equally misleading testing methods has led to the questionable evaluation of fire and toxic smoke risks.
The effect of fires on human beings
When people think of fire as a cause of death, they often think of flames. However, in a list of the four ways in which fire can kill, flames are the least likely cause of death.2
Asphyxiation - Fire consumes oxygen from the surrounding atmosphere, thus reducing its concentration. If oxygen concentration falls below 17%, a person’s critical thinking and coordination may become difficult. When oxygen concentration falls below 16%, attempts to escape the fire may be irrational, wasting vital seconds. With further drops in oxygen, a person loses muscular coordination for skilled movements and muscular effort leads rapidly to fatigue. Breathing ceases when the oxygen content falls below 6%.
Exposure to super-heated air or gases - With temperatures above 300°F (150°C), loss of consciousness or death can occur within several minutes. In addition, hot smoke with high moisture content is a particular danger, since it destroys tissue deep in the lungs by burning it.
Smoke and toxic products - Inhalation of smoke or the products of incomplete combustion can kill without any exposure to flames. In addition to carrying toxic products, thick smoke may be laden with organic irritants, such as acetic acid and formaldehyde. In the early stages of a fire, the irritants that attack the mucous membranes of the respiratory tract are often the more significant danger. In addition, smoke often blocks the visibility of exits, making it even more difficult to flee the dangers of a fire.
As previously mentioned, many toxic components of smoke are responsible for injury or death. These substances include, but are not limited to, carbon monoxide, oxides of nitrogen, aldehydes, hydrogen cyanide, sulfur dioxide and ammonia. Furthermore, there is ample evidence that the combined hazard of two or more toxic gases is greater than the sum of the hazards of each, and low oxygen levels and high temperatures may increase toxic effects. In addition to toxic gases that attack the lungs, there are irritants that attack the eyes, creating blinding effects, preventing escape. Plus, some fire gases dull the senses of the victim or awareness of injury.
Flames - Since the previously mentioned factors can debilitate, confuse, blind or kill with little or no warning, thinking that advancing flames will always be a sufficient warning for escape may be a fatal gamble.
The misconception of the role of insulation in fire propagation
Thermal insulation plays a potentially active role in fire propagation, either by being inherently combustible or by absorbing (wicking) liquids that are themselves combustible. Contributing to this danger is a frequent misunderstanding of tests, classifications, terminology and the protection provided by specific materials. References to “self-extinguishing” and “fire retarding” are often interpreted as the equivalent of “noncombustible.” In most cases, it is not flames, but the smoke and toxic fumes resulting from burning (including “slow-burning” or “self-extinguishing” materials) that cause the highest rate of death or injury.2
The standard “fire triangle” model illustrates the three elements a fire needs to ignite and keep going: a combustible material, an ignition source and a combustion supporter. Eliminate any one of these components and an ongoing fire is not possible. For this reason, it is advisable to use a completely incombustible insulation material, eliminating one of the three elements of fire propagation.
A closer look at fire testing
Nearly all manufacturers make claims related to the performance of their insulation materials in fire exposure situations. Fire testing often results in varying, ambiguous, or even nontransferable data. For example, ASTM E84 - Standard Test Method for Surface Burning Characteristics of Building Materials and ASTM E136 - Standard Test Method for Assessing Combustibility of Materials Using a Vertical Tube Furnace at 750°C are often viewed as the industry standards for fire testing of insulation materials. However, a review of the test methodology concludes that the tests do not appear directly related to the reality of an actual industrial fire. The results of these tests can be significantly altered using fire-retardant additives. While additives can reduce flame spread ratings of plastic foams under test conditions, these may have little retardant effect under actual fire conditions.
Other conditions that can significantly affect actual-vs-tested fire behavior are the substrates on which insulation is applied and the rate at which maximum temperatures are attained in chemical or petroleum fires compared with structural or building fires.
The FOAMGLAS® Cellular Glass Insulation Solution
Cellular glass insulation has been subjected to scores of national and international tests, including under ASTM E-136 and ASTM E-84, EN ISO 1182 - Reaction to Fire Tests for Products — Non-combustibility Test, EN ISO 1716 - Reaction to Fire Tests for Products — Determination of the Gross Heat of Combustion and BS476 - Fire Tests on Building Materials and Structures, to name a few.
In these tests, samples are subjected to furnace conditions, during which both sample and furnace temperature changes and flame development are monitored. If any of the strict conditions are exceeded, a material is classified as combustible. FOAMGLAS® cellular glass insulation has undergone rigorous testing and is classified as non-combustible. This means that using cellular glass insulation helps to eliminate a major component of the earlier discussed “fire triangle.”
A material being classified as non-combustible does not mean that fire risk is completely mitigated. The absorptive nature and composition of the material can contribute greatly to fire and smoke development and increase overall fire risk.
FOAMGLAS® insulation has been widely tested and proven by real-life situations to be non-absorptive to combustible liquids or gases. Non-closed cell material absorption issues are eliminated when using closed-cell FOAMGLAS® insulation.
This is also the reason why engineers often specify non-absorptive, non- combustible cellular glass insulation systems for applications with a risk of leaking organic fluids.
Finally, the inorganic nature of cellular glass insulation helps to minimize the potential fire risk of condensed hydrocarbon gases or liquid oxygen as it is proven to reduce the dangers associated with oxidization of organic materials. Additionally, this also is the reason why FOAMGLAS® insulation does not produce toxic smoke or gases in case of a fire.
Real-life situations have validated test results that showed a smoke development index of zero. This contributes to overall fire safety by maintaining fast and safe access to escape routes and allowing people to reach emergency services more quickly.
Conclusion
Insulation materials play an important role in the fire safety of buildings and installations. However, not all insulation materials react the same in case of fire. Designers should consider a wide range of characteristics when specifying insulation systems for fire protection.
Material properties such as absorption, the potential for development of smoke and toxic gases, as well as combustibility should be considered as part of the strategy for total fire safety of an insulation system.
We can conclude that a closed-cell, non-absorbent, incombustible, cellular glass insulation system that does not add to the spread of fire nor produce smoke or toxic gases can help to ensure maximum fire safety.
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