Fire Alarm -- Description
In case of fire, Total Evacuation is where everyone leaves the building at once, Staged Evacuation is where those in the zone of the fire and adjacent zones leave the building first, Defend in Place is where everyone gets to a safe place in the building.
What is Total, Staged, and Defend-in-Place Evacuation?
By Douglas Krantz
For their own safety, when the fire alarm
sounds, people want to get out of a burning building. Sometimes, though, there's a hitch in people's ability to evacuate; some buildings are easier to get out of than others:
- Smaller buildings have easy escape routes
- High rise buildings aren't easy because they don't have many escape routes
- Hospitals, healthcare institutions, and prisons aren't easy because the residents can't just get up and leave
Each of these situations is different, and each requires its own specialized method of fire evacuation.
Total Evacuation -- Smaller Buildings
Fire! Get Out!
Total Evacuation -- Everyone immediately gets out of the building
Like a school, with Total Evacuation, if the alarms sound
, they sound simultaneously everywhere. Everyone hears the fire horns or speakers, stops what they were doing, and withdraws from the building using fire exits.
In case of fire, smaller buildings are evacuated right away.
Staged Evacuation -- High-Rise Buildings
Fire! Let those in greatest danger escape first.
Staged Evacuation -- The phased withdrawal of the occupants
When there is a fire, if the escape routes are not large enough to handle everyone in a building at once, Staged Evacuation is the orderly withdrawal of people.
In Staged Evacuation, the alarm sounds near the fire. It's like shouting only to those in immediate danger, get out! The alarm sounds in the zone of incident (fire floor) and all adjacent zones (floor above and below).
For the rest of the occupants, there is either silence or an alert sound. It's telling everyone else in the building, those who aren't near the fire, "Stay where you are. Let those in danger get away, after that it's your turn."
Defend-in-Place -- Hospitals, Healthcare Institutions, and Prisons
Fire! Get to a place of safety inside the building.
Defend-in-Place -- Protecting those who can't leave the building
Hospitals, nursing homes, and even prisons present special problems because the people residing in there just can't just leave the building on their own.
In the case of hospitals, people often aren't able to get out themselves, or are put in danger by moving to what for others would be a safe place.
Residents in nursing homes are physically or mentally incapable of fending for themselves, and need assistance.
Prisons, of course, are a place where the residents aren't allowed to leave.
In a Defend-in-Place building, three different types of evacuation take place at the same time:
- Progressive -- Those in immediate danger get moved to a safe adjacent zone in the building
- Defense -- Those not in immediate danger are moved behind protective doors
Evacuate -- Those who can leave, and are not needed to assist in the Progressive or Defense procedures, exit the building
Fire Alarm Evacuation
Which method of evacuation people use -- Total Evacuation, Staged Evacuation, or Defend-in-Place -- depends on how easy it is for them to use the exits.
However, whether it's a Total getting out of the building that's on fire, a Staged withdrawal from the building, or Defend-in-Place inside the building, evacuation is still people protecting themselves from a fire.
In the book "Make It Work - Conventional Fire Alarms
" by Douglas Krantz, I'd like to show you how the fire alarm system works. The book describes the basic fire alarm system. Order Here