FIGHTING FIRE ON CAMPUS - When it comes to blocking flames & smoke, glass is an unsung hero
Reprinted from AS&U Magazine
By Jerry Razwick, Technical Glass Products
In January of this year, tragedy struck Seton Hall University when a dormitory fire claimed the lives of three freshmen students and injured nearly 60 others. What was particularly disconcerting was that the deaths occurred even though the alarms in the building activated properly to warn students of the fire.
According to Associated Press sources, dorm residents had endured approximately 18 false alarms the previous semester. Many students simply concluded that the noise blaring in the night was just another mistake, so they rolled over and went back to sleep. What was believed to be a prank became a genuine danger as deadly smoke from the fire in the third-story commons spread through the halls and under residents' doors.
While Seton Hall's situation was particularly tragic, it was far from an isolated incident. Statistics from the National Fire Protection Association indicate that approximately 1,500 fires occur every year in housing facilities on campuses across the country. In most cases, school administrators assume that the safety measures taken by the school would minimize any damage caused by a fire.
But is that a safe assumption? The dormitory at Seton Hall was equipped with alarms and fire extinguishers, which were all in working order. What no one had taken into account was the response of students. With no sprinklers in the dorm, there was no second line of defense once the fire alarms failed to achieve the intended results.
Yet all too often, even sprinklers cannot provide an absolute guarantee of safety. In fact, some schools rely almost exclusively on sprinklers the way Seton hall relied on alarms. Given the massive sprinkler recalls over the last two years, depending on them as a sole source of fire protection could be questionable.
Both sprinklers and alarms are considered "active" systems, requiring a number of steps to happen in the proper sequence. One unanticipated factor can impair the effectiveness of the entire system. What happens if the water supply valve is shut off? What if the water pressure drops? What if someone painted over the sprinkler heads during remodeling? Or, what if the PVC piping used for the sprinkler system melts during the fire?
Everyone agrees that sprinklers and alarms save lives and dramatically reduce the risks associated with fire. There is no question that they should be installed strategically on every campus. However, sprinklers and alarms only address two issues: how to detect fires and how to suppress them. And if they are anything less than 100% effective, it is critical to also have systems in place to aid in the containment of the fire and smoke.
One of the least likely heroes in this battle can be glass. Glass that is classified as "fire-rated" doesn't require any "activation" to do its job. It doesn�t depend on external factors to perform properly. Whether installed in doors, sidelites, transoms or windows, fire-rated glass stands ready around the clock to help prevent the spread of fire.
While it looks very unassuming, fire-rated glass is actually a sophisticated roadblock, an invisible barrier to flames and smoke. This is a task that ordinary window glass simply can't perform. When heated beyond 250° F, ordinary glass will shatter and fall out of the opening, leaving an unobstructed path for fire and smoke to travel into other parts of a building. By way of contrast, fire-rated glass has been tested in furnace conditions where the temperature exceeds 1600° F. In a real fire, glass that has passed that kind of testing will remain intact, compartmentalizing the space and restricting the expansion of the fire.
Glass is often more desirable than a solid in some locations for enhancing lighting, security or aesthetics. Typically, fire-rated glass is used instead of ordinary window glass in corridors, lobbies, stairwells and other key areas of a building that could serve as an escape route for occupants trying to exit during a fire. The level of fire rating required is determined by several factors that could influence how long people might end up trapped in a burning building.
For instance, the third floor of a hospital might have bed-ridden patients who would find it difficult to evacuate during an emergency. In contrast, a single story elementary school might empty very quickly under similar circumstances. Codes would therefore dictate different fire ratings for the glass, from 20 minutes to 3 hours, depending on how much time is deemed necessary for escape or rescue.
At one time, the only fire-rated glass on the market was polished wired glass. When most people on the street see the familiar criss-cross pattern in the glass, they assume that it is there for safety or security reasons. It isn't. The wire is embedded in the glass to hold it in place during a fire, but not to make it stronger. In fact, wired glass is significantly weaker than ordinary tempered or laminated glass, and can actually cause more injury when it is broken, due to the dangerous snags of broken wire.
Yet for many years, wired glass was the only glazing material that could endure the rigorous testing process to earn a fire rating. It is a widely used product even today, and can be found on the majority of school campuses in North America. But being forced to use wired glass to satisfy fire codes has often meant compromising impact safety. And in some injury cases involving wired glass, schools have learned the hard way that they may be held liable for such compromises.
Fortunately, a number of new glass options have emerged that outperform wired glass in terms of both fire and impact safety. These glasses have also managed to eliminate the need for wire mesh - improving appearances and moving away from the "institutional" look and feel of wired glass. With the growing awareness that environment impacts learning, the new "wireless" fire-rated glass alternatives offer a significantly improved aesthetic for educational institutions.
One of the new product options isn't technically a glass at all: it is ceramic. For centuries, people have appreciated ceramic's properties that give it a high tolerance for heat. Even grade school children learn this firsthand in art class when their ceramic projects go into the kiln. Today, sophisticated ceramic products can be found in cooktops, car engines and gas fireplaces, precisely because ceramic holds up well when things get hot.
Recognizing the value of that characteristic, manufacturers developed a transparent ceramic for use in fire-rated openings. When it is installed, ceramic looks like ordinary window glass, yet it retains its heat-resistant qualities. And while ordinary ceramic can be rather brittle, state-of-the-art technology has produced fire-rated ceramic products with high impact protection ratings. Available in insulated units for exterior applications, ceramic can also be beveled, etched or sandblasted without affecting the fire rating.
Ceramics have been tested to endure something else that is often overlooked: water. When water from a sprinkler or fire hose sprays hot glass, what is likely to happen? It will most likely shatter or explode, because standard glass cannot handle the stress of two different temperatures on its surface at the same time. As was discussed earlier, when that happens, flames and smoke are free to spread through the opening that is left behind. Fire-rated ceramics, however, have passed what is called the "fire hose stream test," and they are unaffected by this type of thermal shock.
Here is yet another example of why reliance on sprinklers alone may be unwise. Properly activated sprinklers may completely extinguish a fire, but in doing so they can generate large volumes of smoke. If water from the sprinklers came in contact with hot, non-rated glass during the fire and the glass shattered, that smoke will spread freely. And since the majority of fire-related deaths are due to smoke inhalation rather than burns, there is still cause for concern -- even after the fire is out.
In some cases, a school design may call for glass that can act as a wall to block heat in addition to flames and smoke. In stairwells, for instance, where people could conceivably become trapped during a fire for long periods of time, the heat could quickly build up to an intolerable level if there were no means of keeping the temperature down. Historically, this has meant using solid barrier walls and only a small amount of glass for visibility as needed.
Recent advancements in fire-rated glass have changed that, making it possible to have unrestricted amounts of glass in locations with 2 hour fire rating requirements. These newer glass products are called transparent wall units, because they are tested to the same standards as walls, and they act as a barrier to the transfer of heat. Tests have shown that even with a hot fire on one side of the glass, the opposite surface of the glass is still cool enough to touch.
Transparent wall units incorporate a range of different technologies, but all work on essentially the same principle. Multiple layers of glass sandwich an inert material which turns to foam during a fire. The foam obscures vision but blocks the heat of the fire.
These and other developments in fire-rated glass have opened tremendous new possibilities for school designers and architects looking for ways to enhance their designs without sacrificing life safety. By utilizing passive fire-rated glass in conjunction with active systems such as sprinklers and alarms, educational facilities can provide the best possible defense against the ever-present threat of a fire.
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