A couple of weeks ago, there was an article published by TYCO, a sprinkler manufacturer, pushing for their alternate 1-2 hour wall assembly using their special purpose deluge sprinkler and tempered glass. In the article, they make the case that tempered glass and deluge sprinklers are cheaper compared to 1-2 hour fire resistive glazing assemblies. However, their estimate only referenced the cost of a couple of sprinkler heads and tempered glass – what they fail to tell the buyer (or the architect) is that there are plenty of hidden costs and safety risks to this assembly.
So before going through the AHJ approval process for this alternate assembly using deluge sprinklers, here are a few concerns to help architects and owners make an informed decision. This is in comparison to readily available, USA-made, 1-2 hour fire resistive glazing assemblies that do not need prior AHJ approval.
Other than following the time and temperature curve, there is nothing that resembles the original ASTM E-119 test for deluge sprinklers with fixed glazed assemblies. There is no cotton waste test, there is no hose stream test, and there is no documented report showing how it provides radiant heat protection by limiting the temperature rise on the non-fire side to less than 250 degrees F over ambient.
The possibility of sprinkler failure also poses a real threat to building occupants. No sprinkler manufacturer or installer will guarantee that it will work 100% of the time. When the sprinklers fail to operate, the non-rated glass will be useless in preventing fire, smoke and dangerous radiant heat from spreading. Building occupants are no longer protected, and safe egress becomes almost impossible. Wetting the surface of heat-strengthened glass or tempered glass may prevent thermal shock and compartmentalize smoke and flames, but it won’t prevent the passage of radiant heat. Ceramics may be able to resist cracking or shattering at high temperatures because it is an excellent conductor of heat. This is why it is widely used as cooktops, and why the IBC limits its use to fire protective applications only because it does not limit radiant heat whatsoever.
After comparing the hidden costs, safety risks and design restrictions on special purpose deluge sprinklers that requires prior AHJ approval vs. already approved 1-2 fire resistive assemblies, it is clear to see that merely looking at this in terms of ‘a few sprinkler heads and tempered glass’ exposes the designer and building owner to various costs and liabilities. For more information, visit http://safti.com/tyco-model-ws-and-firelite-plus-ws-product-alert/.