·~ . A. r�, a ş t ı r m a DETERMINING EFFECTIVENESS OF ATRIA SMOKE CONTROL SYSTEMS An actual atrium fire is compared with the results ofscale model tests that are dynamically simi/ar Fires within large enclosed spaces present unique challenges and opportunities. Debate has raged back and forth within and without the regulatory community ever since these buildings became commonplace. However, little serious discussion has revolved on the technical issues in setting many of the regulations. Before examining the fluid dynamic effectiveness or ineffectiveness of various proposed or required smoke removal schemes, it is first important to define the scope of the problem. Typical large enclosed spaces are often thought of as malls, atriums and stacliums. Malls are most frequently a linear arrangement of mercantile shcps and are usually limited in height. Mail shops have significant fuel loads, often with heat release rates greater than 45 Btu/s/ft2 (500 kW m2). The arrangement of the fuel packages can be quite compact ancl alarmingly vertical. The separation of the typical shop from the roofecl pedestrian mail in most North American complexes is nonexistent. While the pedestrian mail was original intended to be virtually clevoid of fuel and provide for the swift ancl orclerly evacuation of occupants, such is no longer the case. The peclestrian mail has evolvecl into sales and exhibit space of its own, containing substantial fuel loads and numerous sources of ignition. it has also grown from the initial single story arrangement to commonly two levels, occasionally three and even more levels. Hinckley2 Butcher and Parnell3 and others have discussed in great detail the methodology of preserving the safety of occupant egress routes in the sterile, single story mali. However, the complexity of the unusual geometrics of modern multistory malls with fuelladen pedestrian exit paths is a far different problem. Atriums that are generally distinguished by greater height are often associated with hotels. However, atriums are finding their way into offices and many other applications. By Michael E. Dillon, P.E. Fellow ASHRAE in particular, North American atriums have evolved from the fairly simple conclition of a large vertical volume surrounded by open balconies leading to guest rooms to complex geometries incorporating virtually every type of public use and accommoclation. The original concept may have had some validity in that; it limited the clistances of travel from an individual hotel room to an enclosed exit; it provided for a high degree of compartmentation by isolating the hotel rooms; and, with the limitations on materials within the atrium, it provicled an extraordinary volume for the dilution of the limited smoke generation capacity. Today, the limitation on smoke generation is all but nonexistent. The height of these facilities has always called into question the effectiveness of the fire sprinkler protection. The physies of the situation has always belied the common myths of naive air change rates and makeup air introduction. Enclosed stadiums present many of the same problems as discussecl above, but they expose much greater populations to the hazards. Enclosed stadiums have grown substantially in size, number and cliversity of hosted activities. Operations of such facilities in North America do not generally limit the use of these buildings to low fuel loacl sporting events such as football, hockey, baseball and basketball. lnstead, many stadiums routinely have significant pyrotechnic displays. Some have "monster" truck races, motocross motorcycle events, truck and tractor pulls, and even indoor carnivals with midways and rides. The fuel loads and arrangements at these events can be considerable. With 20,000 to 40,000 people arrangecl vertically, open to the event and constrainecl to exit along steep aisles, the prospect of an unwanted and uncontrollecl fire is frightening. Another subsclass of facility that is not truly in the above 107
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