Directional Sounders Part III

Which Way Out?


Basic type 1 installations
The simplest of designs, these are located in close proximity to what your building/fire code deems as the “exit” door. This exit may open directly to the outdoors, but may open to a “vertical exit element” such as a stairway, or a “horizontal exit element” such as a passage to another building or corridor leading to a separate fire area. Since some physically handicapped persons cannot use stairs, they may need rescue assistance; sounders should be located at any door into an “area of refuge.” Ships and buildings that have exits on several levels can use an optional “slow whoop” to sound every six cyclesto indicate which direction the occupants need to take inside a stairwell. For example, a sweeping sound from low to high means to go up the stairs. (The best evacuation times and highest percentages were seen when the directional sounder’s various signals were explained beforehand. However, even when the audible cues were not explained prior to the smoke filled corridor trials, most occupants instinctively followed the pulsing sounds and went the correct direction in the stairwells.)

When a fire alarm signal is heard by the occupants, they move from their rooms to the hallways and need to get moving on the most direct path to an exit. But which way is out?

A. Directional sounder A leads the telemarketers along the path of travel that will take them directly to an exit stairwell.
B. Sounder B is located at both an exit plus an area of refuge. This sounder will be set to produce another optional tone (also repeating every six cycles) indicating that this exit also contains an area of refuge. Sounder B should have its volume high enough to pull people from a distance, and may need to be louder than the fire alarm.
C. Other office workers will move toward sounder B.
D. If not for sounder B, these occupants at D might miss the exit stairway and wander into the dead-end corridor toward E, possibly resulting in their death.

Advanced type 2 installations
Advanced installations are used where occupants will need to make decisions about which way to go. These installations require additional sounders to be placed along the occupant’s common path of travel in buildings that have confusing hallway layouts and dead ends. When occupants are not familiar with the building’s layout, or are in the habit of leaving the way they came in and cannot see an exit because of smoke, they may miss their chance.   Install these sounders to prevent them from retracing their path or missing their last chance.

At the decision points along the exit path, directional sounders are used to provide audible clues guiding them toward the nearest exit. Additional sounders are added to a Type 1 installation to keep occupants moving toward the exit by using the pulse speeds to create an egress pathway to the emergency exits. Notice that when sounders are installed along the exit path, they are placed just after where the occupants move past a turn (within two feet).

A. The A sounders are set to the fastest pulse setting. The fastest pulse setting is to be used only at the exit or refuge area. This sounder might also be set to the highest volume, which may be louder than the fire alarm.

B. Sounders at B, set to pulse at a medium speed, are used to keep people moving confidently toward the exit. Sounder B1 may also need to be set to be a little louder than sounder C.

C. Sounder C is pulsing the slowest and should be set at the same or lower volume settings than the next sounder, B. Sounders C and B2 keep occupants from moving down a dead-end corridor. If the occupants are closer to the center of the building and hear a sounder pulsing faster than sounder C, then they should move in that direction.

Each directional sounder incorporates an optional disable feature using two normally open wiring terminals. An automatic heat detector may be connected to disable one or more sounders so as not to draw occupants to a more dangerous area or even away from the logical path of egress.
Directional sounder capabilities are impressive and if used properly, will most certainly lower exit times and save lives.

Greg Kessinger is the former chairman of the NBFAA Life Safety Committee.