By Jerry Razwick
Sprinkler systems have become one of the primary means of fire protection in
commercial buildings, and with good reason. They have a proven track record
of saving lives and property. However, the assumption that sprinklers are the
only necessary defense against fire can have disastrous consequences. Exclusive
reliance on sprinklers for protection may open the door to even worse fire damage
than no sprinklers at all.
Case in point: When activated during a fire, sprinklers can cause most types
of window glass to shatter within a few minutes. This may leave large openings
for fire and smoke to travel freely through a building.
That is just one possible scenario. Here are a few examples of commonly held
misconceptions about the use of sprinkler systems near glass:
"You can always count on sprinklers to operate." Unfortunately,
such is not the case. Recently, 35 million sprinkler heads were recalled nationwide
because of a design flaw discovered after the systems were already installed.
Regrettably, the flaws were only discovered after several fires had occurred.
Even at their best, sprinkler systems are only as reliable as the maintenance
they receive, which can lead to a dangerous false sense of security.
"All sprinklers can properly protect glass during fire."
The sprinklers typically used in commercial construction are not designed to
protect glass during a fire. Only special "deluge" sprinklers that
have specific installation and other sometimes unrealistic requirements may
offer some protection.
"Deluge sprinkler systems keep glass cool during a fire."
Laboratory tests have shown that the effectiveness of deluge sprinklers depends
a great deal on where the fire starts in relationship to the glass, how quickly
the sprinklers are activated, and other hard-to-predict occurrences. Since no
one can predict where and when a fire will strike, relying exclusively on deluge
or other sprinklers to cool the glass may be an unsafe choice.
"Tenants will abide by guidelines for the special deluge sprinklers."
Unless the water evenly cools 100 percent of the glass surface, there is a high
probability that the non-rated glass will fail during a fire. Some deluge sprinkler
manufacturers say that no curtains, blinds, or other such products are allowed,
since they may prevent water from reaching the glass. However, such restrictions
are impractical and may not be known or followed by building tenants, thereby
innocently jeopardizing fire protection.
"Sprinklers are compatible with all fire-rated glass."
Not all fire-rated glass is equal. Codes in the United States require that all
glass fire-rated for 45 minutes or more must pass the hose stream test. If sprinklers
are nearby, make sure that the glass in the area carries at least a 45-minute
rating with no restrictions or limitations on the listing.
"Sprinklers eliminate the need for fire-rated glass."
While sprinkler systems have usually proven effective as life-safety devices
in fire protection, they have their limitations. The best solution is to utilize
sprinklers in conjunction with fire-rated glass and framing systems that pass
the hose stream test. By using tested "passive" fire-rated glazing
systems, protection is provided even if the "active" sprinkler system
does not work properly - or if there is no sprinkler system at all. Redundant
fire-rated protection systems offer the best possible solution.
Jerry Razwick is president at Technical Glass Products, Kirkland, WA, a
well-known national distributor of fire-rated glazing and framing materials
such as the FireLite family of products, Pyrostop, Fireglass20, and Fireframes.
for more in-depth information on fire-rated glass and framing.