Protecting people is generally referred to as "life safety." Of course, completely avoiding a fire through the effective use of prevention measures is the first goal. However, should a fire or other emergency occur, there are critical life safety issues to consider. Mainly, occupants need to be provided:
- Clear warning that an emergency exists;
- Time for escape;
- Sufficient number of properly located useable exits; and
- A clear path of escape.
Clear warningThe best way to provide warning of an emergency situation is via an installed detec-tion and alarm system. This should be supplemented with a voice communication system that provides specific instructions to occupants.
"Clear warning" means that occupants understand that they may be at risk. A fire alarm alone does not necessarily accomplish this, as peoples' responses to a fire alarm vary widely, from leaving immediately to ignoring it completely. Responses of occupants are based on their perception of risk.
An alarm system has to first detect the emergency, and it must have a low potential for false detections. Frequent false alarms teach occupants not to trust the system. The detection system must also sense the presence of an emergency condition early. Occupants should be given as much warning as possible of the situation to allow the maximum time for escape.
Once the emergency has been detected the alarm should provide a clear warning to all occupants of the building. This means it must be capable of being perceived above ambient conditions - it must be loud enough to overcome background noise and distinctive enough to be unique from among all the other signals. Typically, fire alarms provide a combination audible and visual warning.
Ambient noise conditions also present a challenge to alarm systems. In many work settings background noise can be substantial. Personnel may be required to wear hearing protection. The alarm system must be designed to overcome all of these challenges.
A supplemental public address system enables specific information and instructions to be provided to occupants and improves their chances of perceiving the risk and taking action. By announcing the specific nature of the emergency you assure occupants that it is, in fact, a real event. This also allows you to convey detailed information - for example, if the emergency is on one side of the building you can tell people to exit on the other side.
Time for escapeTime for escape is provided in part by the early warning of an emergency given by the detection and alarm system, and in part by containing the emergency and limiting the speed of its growth and spread. Construction features are one of the tools used to accomplish this. Compartmentation is the concept of dividing the building into distinct fire areas and constructing these areas in a way that prevents the spread of fire and smoke from one area to another.
Installed extinguishing systems are another component of containing and limiting the growth of a fire. A sprinkler system, for example, will discharge water on the fire while it is still in the early stages. These systems will often extinguish the fire before it can grow beyond the area of origin. Of course, extinguishing systems need to be regularly inspected and maintained.
Useable exitsA sufficient number of exits are required to allow the prompt escape of occupants. These exits must be properly located. At least two exits should be available from any given area, and they should be located remote from each other. This is so no single event is likely to block both exits.
Proper location also means that people should not have to move toward a more hazardous area to reach an exit. For example, in an industrial setting, people working in the production area should not have to pass through a flammable liquid storage area to reach an exit.
Path of escapeYou must look at the entire escape path when considering evacuation of a facility. The first part of the path is the exit access. This includes all of the area that a person may need to cover from where they are at the time the emergency occurs until they reach an exit. The second part is the exit itself. In simplest form this is the door that passes through an exterior wall to the outside of the building. In a multistory building, the stair tower, if properly constructed, is considered the exit. From the area immediately outside the exit to a location safely away from the building is called the exit discharge.
Part of making a clear path for escape is marking exits. All exits must be posted with signs. If the exit itself is not visible from all parts of the area then illuminated directional signs indicating the path to the exit are necessary. Emergency lighting, powered by a backup source such as a battery, is also needed to ensure that occupants can find their way to an exit if the building loses electrical power.
All portions of the escape path must be maintained, unobstructed, unlocked and frequently inspected.
Count headsIn a work environment an additional element should be covered: accounting for personnel after they have evacuated the building. Have a system that will allow you to confirm with a reasonable degree of certainty that all of your employees have been evacuated from the facility. This will usually include designated assembly areas outside the building and a method for conducting a head count of occupants.
SIDEBAR: Inspect, test and maintainEffective system design, installation, inspection, testing and maintenance are critical to ensure the proper operation of your alarm system. While design and installation are one-time events that you may have little or no direct control over, your primary day-to-day focus is on the inspection, testing and maintenance of the installed systems. Some tips to remember are:
- Regularly inspect all components of the system.
- Conduct testing of the system at least annually.
- Test both the detection and alarm portions of the system. Alarm portions should ideally be tested during normal facility operations to confirm that the alarm can be detected above ambient noise conditions.
- Required maintenance should be completed promptly by competent personnel.