Huh?
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of å... ....
Sent: Monday, October 01, 2007 4:57 PM
To: [email protected]
Subject: Elevator Fire - pictures and clarification...
Without testing, one can not reliably
say how effective the sprinkler at the
top of the elevator shaft would have been.
Especially if this car recalled to the bottom of the shaft; sprinkler water
would primarily wet the walls if this was a one car shaft.
Then there is consideration of shielding that the roof of the elevator car
provided. Probably too many variables to say what the advantage or
stalemate would have been.
Had the car returned to the primary recall floor and opened its doors, this
would have provided valuable oxygen that otherwise was more limited had the
fire burned in a closed shaft.
Then again, a closed shaft would have reduced entrainment, and kept the
smoke hotter.
Certainly sprinklers in the corridor near the elevator car doors would have
helped reduce the HRR in this case, although there is the liability of
putting lots of water into an elevator shaft with other cars. The scrubbing
benefits from sprinkler water might be measurable on soot and smoke
temperature, but virtually ineffective on CO dispersement. You have no
support here, for the water curtain strategy.
As mentioned by CC, these fires are extremely rare, such that in the case of
at least high-rise buildings where:
a. elevator shafts should be surrounded by
smoke-resistant lobbies, and
b. cars should be noncombustible,
if a fire does occur, the smoke should not spread in untenable amounts past
the elevator lobby, with the result that the remainder of the building stays
tenable (at least for the duration of egress) despite one evidently
plausible worse case elevator-system fire presented to us.
Before deciding to return to a sprinklered elevator shaft, we should weigh
in the advise from professional research projects focussed specifically on
elevator system fire safety, as this is an active field of investigation at
the moment. One fire does not warrant a change in risk categorization for
elevator system fires.
Lesson learned: remove combustibles from elevator cars, shafts, etc.
NOTE: this is not an endorsement of Fire Retardant chemicals (for reasons
related to the environmental costs of generating and applying these
chemicals) in lieu of removing combustibles. An it is realized some power
cables are run inside elevator shafts, and they will remain.
New building designs should consider tenable egress from elevator fires
(what if someone is moving a couple of sofas in the elevator). One approach
is emergency notification and exit placement such that this situation is not
repeated [where students (a rather robust occupant) were afraid to use the
corridor and exit to a stair (apparently on a floor remote from the fire)
because the corridor was too choked with black smoke (a surprising finding
to my intuition)] under non-stack,
non-wind conditions. Alternatively, a smoke control design could
be as simple as constructing a passive elevator lobby with active doors held
open by magnetic hold opens. Both the exit and smoke control approaches
require sufficient documentation to validate their probability of success in
the light of building maturation (i.e.under duress of some component
failures) as well as performing simply in the line-of-fire.
There are enough details and interrelated disciplines (elevator, mechanical
ventilation, electrical backup power supplies, egress, and good
old-fashioned sprinkler protection) that making an out-of-hand prescriptive
design paradigm from this case might be short sighted, though that should
not stop us from suggesting potential strategies for peer review.
scot deal
excelsior fire engineering
_______________________________________________
Sprinklerforum mailing list
[email protected]
http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum
To Unsubscribe, send an email to:[EMAIL PROTECTED]
(Put the word unsubscribe in the subject field)
_______________________________________________
Sprinklerforum mailing list
[email protected]
http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum
To Unsubscribe, send an email to:[EMAIL PROTECTED]
(Put the word unsubscribe in the subject field)
