• <br />• <br />E <br />VOICE ALARM SYSTEMS <br />Voice alarms automatically send a voice evacuation <br />message to speakers in selected areas of high-rises <br />or expansive buildings, hospitals, and other build- <br />ings where total evacuation is impractical. A typical <br />high-rise arrangement would provide for the fol- <br />lowing areas to automatically receive a pre-recorded <br />evacuation signal: the floor where the alarm origi- <br />nates and the floors above and below it. Arriving <br />firefighters can evacuate additional areas by manu- <br />ally activating one, multiple, or all floors with the <br />manual select switches in the command center. <br />They also can override the pre-recorded message <br />and broadcast live voice announcements to any or <br />all evacuation zones with a microphone at the com- <br />mand center. Adjacent to each manual select <br />switch, visual indicators show which evacuation <br />zones are activated at any given time (Figure 6.7). <br />Arrangement of evacuation zones depends upon <br />the design of the building and any evacuation plan <br />in place. Each floor is typically one evacuation <br />zone. Areas that are not separated by fire or smoke <br />barriers should not be divided' into multiple evacua- <br />tion zones. However, if a floor is divided by fire or <br />smoke barriers to enable occupants to take refuge <br />on either side, multiple evacuation zones should be <br />provided. Operators at the command center will <br />only be able to give different instructions to those <br />on either side of the barriers if the zone boundaries <br />coincide with the rated barriers. <br />56 <br />In addition to normally occupied spaces, most <br />building and fire codes require speakers in stair- <br />ways and elevator cabs. Each stairway and each <br />bank of elevators should comprise a single evacua- <br />tion zone. In a building with selective evacuation, it <br />is undesirable to automatically activate the speak- <br />ers in these areas. Also, there are typically no <br />detectors to warn of fire or smoke within the stair- <br />ways or elevator cabs. Each of these zones typically <br />has "manual-only" selection capability for the oper- <br />ators in the fire command center. If a stairway has <br />detectors, the speakers in that particular stairway <br />could be configured into a separate, automatically <br />activated evacuation zone. Designers should ensure <br />that evacuation signals are not heard in areas that <br />are not to be evacuated. <br />z <br />(Fig. 6.7) The grey panel is a voice alarm panel. The <br />lower window shows the microphone and the manual <br />select switches for the different evacuation zones. <br />O% '11 <br />Occupational Safety and <br />Health Administration <br />172 <br />