Elevating Your Expertise Elevators are like a proverbial double-edged sword — on the one hand they save a lot of time and steps, on the other they can become a nuisance when they trap someone between floors. It’s even more of a problem when the cause of the stoppage is a fire alarm system.
Not only is it no fun to be trapped inside an elevator, but it’s especially no place to be when there’s a raging fire in a multifloor building. Under those circumstances it’s extremely important an elevator not only operate, carrying its occupants to safety, but that it does so by delivering them to the right floor. To do otherwise can result in injury or death.
This month, we’ll take a look at some of the issues surrounding effective elevator recall and shutdown.
Recall Vs. Shutdown
Recall and shutdown are two important facets of a multiple-floor fire protection program. The need to safely and effectively interface an elevator control system with a fire alarm is second only to the need to evacuate the structure itself.
There are two important tasks that must be addressed when a new fire alarm is installed: elevator shutdown and elevator recall.
Elevator recall involves the reordering of an elevator car, or lift, to a safe and secure position within a building when a fire is detected by specific smoke or heat detectors. Elevator shutdown is where mainline power is disconnected from the elevator to disallow further use.
Shutdown is supposed to occur after recall simply because the occupants must be deposited in a designated safe area of refuge within the building or on a floor where they can easily make their way to safety before mainline power is disrupted.
Smoke Detectors & Elevator Recall
There are still some installers who believe that when the structural fire alarm system detects smoke, elevator recall should be invoked. However, Section 18.104.22.168 of NFPA 72, 2007, says that only those smoke detectors located in the elevator lobbies, hoistway and in a machine room should be used for this task.
One of the reasons why we no longer invoke elevator recall any time the structural fire alarm systems go into alarm involves the distinct possibility that someone could be injured or killed if the floor the elevator happens to be recalled to is engulfed in flames.
There are actually two locations in a building to which a lift can be recalled. The first is referred to as the designated level recall and the second the alternate level recall.
The reason there are two recall levels involves the location of a detected fire. For example, if the fire happens to be on the same level as the accessible area of refuge or horizontal exit, and if the elevator lobby smoke detector on that level has detected smoke, the last thing you want the elevator to do is stop to deposit its occupants on that floor.
Sections 22.214.171.124.1 and 126.96.36.199.2, NFPA 72, 2007, provide valuable insight regarding both recall areas.
For example, a lift should be recalled to the designated level when 1) one of the automatic recall detectors in any elevator lobby but the designated level detects smoke; 2) when an automatic recall detector in an elevator machine room detects smoke, other than when it’s on the same designated level; and 3) when an automatic recall detector in a hoistway detects smoke.
The same lift can be recalled to the alternate level when 1) the automatic detector on the designated level detects smoke; 2) when the automatic detector detects smoke in a machine room on the same designated level; and 3) when smoke is detected by a recall detector positioned in a hoistway at or below the lowest level of recall, providing it’s located above the designated recall level.
Recall Smoke Detector Placement
Where there’s elevator shutdown there’s elevator recall. The latter requires a series of smoke detectors, usually one in a sprinklered hoistway, one in each elevator lobby, and another one in the elevator machine room, which is usually sprinklered the same time as the hoistway.
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Fire/Life Safety · Vertical Markets · Other · Fire/Life Safety 2 ·
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