By Charles Bailey
The idea of exposure protection is to find a way to absorb the heat the exposure is being subjected to. Our primary method for doing this is by putting water directly onto the threatened exposure, which protects the exposure in two ways. First, when the radiated energy from the fire encounters the water, it is able to absorb some of that energy, which prevents it from being absorbed by the structure. Second, when given a porous surface, the water will soak into it, increasing both its moisture content and the amount of energy it takes to make that surface burn.
Because most of the exterior exposures we protect have vertical surfaces, it means that while some of the water we apply adheres to it, a great deal does run off. Therefore it’s critical that a continuous supply of water be applied to the surface as long as it is threatened.
Full article: Protecting the Exposures