LUBA RET. EX 076/077 RE-E - Laserfiche WebLink

LJ • occurs upon or prior to the discharge of water, usu- ally when heat detectors mounted next to each sprinkler head are activated. These heat detec- tors have both a lower temperature rating and a higher sensitivity (a lower response time index) than' the sprinkler. However, to minimize the chance that firefighters will be trapped by a power shutdown, the temperature rating of the heat detec- tor should be as high as feasible. Another shut- down method involves water flow detectors; however, these detectors cannot employ a time delay, so designers seldom choose this method. Note that in many cases NFPA 13, Standard for the Installation of Sprinkler Systems, permits sprinklers to be omitted from these areas. The National Fire Alarm Code, NFPA 72, requires that smoke detectors in either the elevator hoistway or the elevator machine rooms trigger separate and distinct visible annunciation at both the fire alarm control unit and the fire alarm annunciator. This alarm notifies firefighters that the elevators are no longer safe to use, and it also provides some warn- ing time prior to the shutdown feature that is required with sprinkler protection. In addition, ANSI A17.1 requires a warning light in elevator cabs to flash when an elevator problem is imminent. Stairs NFPA 1, NFPA 101, NFPA 5000, the IBC, and the IFC all require that identification signage be provided inside stairwells at every level (Figure 2.22). These standards all require stairwell signs in buildings over a certain height, but the height thresholds vary. Signage should show the stair identifier, floor level, terminus of the top and bottom, roof accessi- NO ;ROOF ACCESS F01F1 i 1 ` THRU 5 I FOR STFIET Elm bility, discharge level, and direction to exit dis- charge. On floors that require upward travel to reach the exit, a directional indicator should also be provided. It is important that these signs be located 5 feet above the floor and be visible with the stair door open or closed. In hotels or other buildings with room or suite numbers, the signs should also include the room or suite numbers most directly accessed by each stair on every level, (i.e., second floor of stairway 3 has direct access to rooms 202 through 256). The latter signage would be extremely important where certain stairways provide no access to some sections of the building. Buildings more than 3 stories in height above grade should have roof access. The IBC and IFC require this, except for buildings with steeply- pitched roofs (with a more than 4:12 slope). As stated above, the IFC, the IBC, NFPA 5000, and NFPA 241 contain special construction/demoli- tion requirements. One stairway should be com- pleted as construction advances. Conversely, as demolition progresses, one stairway should be maintained. These standards also address lighting, and fire rating of the enclosure. Stair Capacity Building and fire codes typically require that stairs accommodate exiting occupants. Fire service per- sonnel who may use the stairs are not factored into exit capacity calculations. In situations where occu- pants are still exiting and firefighters are using the same stairs to enter the building ("counter-flow"), the evacuation may take longer. Furthermore, in most cases, stairway capacity is designed based on the floor with the highest occupant load. Typically, stairs are not widened as one travels in the direction of egress unless the stairs converge from both above and below. This approach assumes that people will evacuate in a phased manner, beginning with the floor(s) closest to the fire origin. In an immediate general evacua- tion, or when people from other areas self-evacu- ate, the increased load will slow evacuation. Both of these bottlenecks will be made worse as the height of the building increases. Furthermore, total evacuation is becoming more commonplace due to concerns about terrorism. (Fig. 2.22) Stairway ID sign. 24 OSHA Occupational Safety and Health Administration 140