Preventing catastrophic fuel vapor explosions

SafeCrest open pore reticulated polyurethane foam for explosion suppression applications contains a network of skeletal strands with 98% void space at any pore size The material functions essentially as a three dimensional fire screen similar to a safety fire screen over a lighted Bunsen burner.In a fuel tank, the empty space above the fuel level (known as the ullage) may readily contain an explosive mixture of fuel vapor and air. It is in this ullage area where an explosion can occur, should it be ignited by any source.Since the liquid fuel itself does not explode, a completely filled tank is far less likely to explode than one that is not full.Obviously, the lower the fuel level in the tank, the greater amount of explosive vapor present. When an ignition source is present (perhaps from a spark), the vapor adjacent to the spark ignites rapidly (Figure 1). This ignition, in turn, ignites the vapor around it, creating a "chain reaction" as the ignition, or "flame front" gets larger and moves faster as it propagates through the vapor (Figure 2). The rapid ignition and propagation of the flame results in an ever growing compression wave in front of it, compressing the unignited vapor, thus adding even greater force to an explosion (Figure 3). This sequence occurs in milliseconds. SafeCrest prevents this chain reaction from occurring; instead, vapor ignition is confined to the area immediately around the ignition source (Figure 4). Flame and wave propagation are mitigated by the foam to below propagation levels (Figure 5), thus preventing a catastrophic explosion (Figure 6).

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