That is a good point, Ed, that you make regarding active mechanical smoke control. You have a fan here, regarding "should" work when speaking about mechanical smoke exhaust.
Other "should´s" have higher woulds. So what about a recent NFPA statistic that sprinklers "should" work 90% of the time? Is this corroborated in Europa, Australia, South America, Asia? Is this unacceptably low to anyone else? Does this need to be changed by more accurate statistics, better maintenance or a combination of both? scot deal excelsior fire engineering On 10/2/07, Ed Vining <[EMAIL PROTECTED]> wrote: > > I don't think "should" counts for much in the real world. When the > Transamerica Building in San Francisco had a fire some years ago, it was in > an elevator cab. Janitors went to lunch around 9:00 PM, leaving their tote > bins in the elevator. More than likely a discarded cigarette did the > deed. The elevator shaft exhaust system did not operate > automatically. None of the fancy floor above, fire floor, floor > above worked automatically. The knob on the door to the fancy manual > controls in the first floor lobby still had dust on it. It was not > used. There was smoke throughout the building. > > Any or all of that stuff SHOULD have worked. > > > > "å... ...." <[EMAIL PROTECTED]> wrote: > 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) > > > > [EMAIL PROTECTED] > Ed Vining > 4819 John Muir Rd > Martinez CA 94553 > 925-228-8792 > _______________________________________________ > 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)
