Guest blog post by Dave Bauer
Every now and then in our Elevator Smoke Protection world, something we thought everyone knew turns out to be something everyone did not know. I’m talking about how the “Elevator Recall” works together with a smoke curtain installed to prevent smoke from migrating via the elevator shaft in mid and high rise buildings.
“What is Elevator Recall?”
Elevator Recall consists of two parts, Phase One and Phase Two, but taken collectively Elevator Recall is the removal of the elevator from the public’s accessibility and control, reserving it for use by the Fire Department. Phase One simply returns the elevator cabs to the primary recall level (or secondary recall level if the detection of smoke was on the primary level) and locks it in place until the Fire Department takes control of that cab upon initiation of Phase Two Recall for its use in fire-fighting operations.
“What triggers Elevator Recall?”
Okay… great. So what triggers what? Let’s do Phase Two Recall first since its so simple. The fire department is in charge and they use their key to initiate Phase Two Recall and use the elevator cab exclusively because it is waiting in a locked position on the recall floor when they arrive. Of course they take great caution if they decide to use the elevator for firefighting operations. For example, they generally do not take the elevator to the fire floor. Instead they do their staging 2 or 3 stories below the fire floor. and use the stair with the water supply to enter the fire floor.
Now let’s backtrack to Phase One Recall. Let’s start by erasing a potential misconception; the fire control panel has nothing to do with elevator recall. Only the smoke detectors in front of the elevator, in the shaft, and in the elevator equipment rooms trigger Phase One Recall. Those smoke detectors may send a signal back to the panel saying that smoke is present at that location, and then the panel does its thing with blinking lights and other cool stuff, but the control panel does not recall the elevator. In other words, if smoke is detected at the loading dock, that smoke detector does notify the fire control panel but the panel does not initiate recall of any elevator. That elevator remains active and usable by the building occupants until (or, if) smoke migrates to a detector in front of the elevator, in the shaft, or in the elevator equipment room if they have one. And then, as mentioned, when the fire department arrives they have a key by which to take control of the elevator cab of their choice upon initiation of Phase Two Recall. They can do that. They’re the fire department.
To restate this once again redundantly, the fire control panel does not control or initiate elevator recall.
“Why is this important?”
We consistently tell design teams and AHJ’s that Smoke Guard connects to the local smoke detector, specifically that smoke detector immediately in front of the elevator. “Immediately” means on the ceiling (not the wall) within 21’ of any elevator door (according to NFPA 72). Someone at Smoke Guard years ago was very smart, and prescribed this connection such that we remain in sync with the elevator come hell or high water. To show what happens if you don’t, I blissfully get to mention a competitor of Smoke Guard. Unlike Smoke Guard, they do not connect to the smoke detector, but instead rely upon a signal from the fire control panel. When smoke is detected anywhere in the building, the panel is notified and the panel in turn directs their units to deploy, regardless of whether or not the elevators have gone into recall. Their website cut sheet says “SYSTEM CONTROL: Group Control Panel (GCP) The curtain deployment mechanism is directly synced and integrated in the fire alarm emergency systems.” This not only takes a bunch of coordination with the fire alarm people but has the potential to be be dangerous to building occupants. The Smoke Guard system only deploys when the elevator cars are off line in Recall so there is NO possibility that a occupant would encounter a deploy curtain while exiting the elevator car. This cannot be said about the competitors system because the way it is wired the curtain could be deploying while the elevator cars are still in service. This is not a good thing.
In order for the competitor to work like a Smoke Guard system (in this one aspect), the following has to happen:
- The fire control panel has to be programmed such that it recognizes that the elevators have entered Phase One Recall.
- The fire control panel has to direct this competitor’s controller to deploy their curtain(s) at the floor at which smoke was detected.
- The competitor’s units must have a dedicated controller for each bank of elevators, typically required to be unique to each floor. If not, all of their units on that controller will deploy together no matter how the fire control panel was programmed. Often the competition will try to get away with a single controller for multiple floors of a building (and conveniently avoid putting it in their bid price).
Conversely, Smoke Guard requires no special programming, no need for anyone to police how may controllers we have, no need to indirectly hope that we work with the elevators and not against them, no need for the Contractor to wonder what gaps he’ll need to pay for, but instead Smoke Guard remains integrally in sync with elevator operations in a virtually foolproof way.
There are other differences as well, such as manual egress, valid testing, and other fun stuff. But when someone says “it’s the same as a Smoke Guard”, remember how this all works and make sure to point out that the competition is NOT the same as Smoke Guard even in just this small but important way. And if you want to see something disturbingly funny, tell a the specifying architect that he gets to coordinate all this; then watch the expression on his/her face.
I’ve attached a link to an excellent article on recall operations and logic if you want to learn more: http://www.affiliatedinc.com/elevator-recall-integration-with-fire-alarm-systems/