Mike Irwin
Member
Don Gault,
Just saw your message about the sprinkler system.
It's apparent that you don't understand how the sprinkler systems on tall buildings work.
The sprinkler systems most of us are familiar with, ones that are installed in relatively low rise buildings like apartment buildings, some homes, and schools, generally work well when supplied by water taken from regular service mains.
The line pressure is normally more than enough to provide water in sufficient quantities to suppress a fire.
However, gravity eventually wins over line pressure, and you simply can't force water to go any higher without pumps. But supplying constant pump pressure to a sprinkler system in a 110-story building isn't feasible, either. You'd need to have multiple pumping stations. And what if there's a massive power failure, as there was a few weeks ago?
So, the most logical method of providing fire suppression cover is pumping water into static tanks. Yes, you need to do the relay pumping, but you don't have to do it to fill the static tanks as they are drawn down.
And since you're already pumping potable water up into holding tanks (that's the water that's used to flush toilets, provide water in drinking fountains, etc.), the approach in the past has normally been to simply pump water into large holding tanks for the sprinkler system, as well.
(Here's a secret... Ever been in a high rise apartment building or hotel that has a swimming pool on an upper floor? Guess what the pool is part of in many cases... The sprinkler system! It's one of the holding tanks.)
Once you have water in the holding tanks, gravity does the rest -- the water flows through standpipes to individual sprinkler heads as it's called for.
Now, imagine a plane loaded with 24,000 gallons of jet fuel kerosene crashes into the building.
I'm sure you remember the images... The planes go in one side of the building, and on the opposite side LOTS of stuff comes flying straight through the wall and down into the streets.
Remember, too, that those aircraft will impact not just a single floor, but several floors at the same time (they're taller than one floor is high), and one, if not both, planes hit at angles that transected several floors.
Immediately you have a massive breach of the pipes that supply the fire sprinklers in the areas where the jets hit, and likely in a swath right through the building to the other side. Standpipes AND individual trunk lines, on which the sprinkler heads are mounted, are destroyed, causing massive ruptures. Some likely would survive, but given that a disaster of this type was never anticipated when the building was designed, the sprinkler system is generally a large unit -- it's not branched or isolated.
The jet fuel also ignites fires over huge expanses of the floor, which means that those sprinkler heads that do survive are going to activate. They'll suppress the fire in those small areas, to some degree, but what good is that if all around that area an out-of-control fire is raging, and the sprinklers in those areas are destroyed?
So we have a unique situation. The sprinkler system was never designed to deal with such a massive fire, and it was never anticipated that the system would be catastrophically breached in so many places, rendering it largely ineffective.
And there's only a limited amount of water in the static tanks, and a large part of that is running out of the broken pipes and doing nothing to suppress the fires that are now raging across several floors.
Quite frankly, given the situation faced on September 11, I don't think any type of fire suppression system would have survived the catastrophic impact of a fully loaded jet liner going at 500 MPH.
Just saw your message about the sprinkler system.
It's apparent that you don't understand how the sprinkler systems on tall buildings work.
The sprinkler systems most of us are familiar with, ones that are installed in relatively low rise buildings like apartment buildings, some homes, and schools, generally work well when supplied by water taken from regular service mains.
The line pressure is normally more than enough to provide water in sufficient quantities to suppress a fire.
However, gravity eventually wins over line pressure, and you simply can't force water to go any higher without pumps. But supplying constant pump pressure to a sprinkler system in a 110-story building isn't feasible, either. You'd need to have multiple pumping stations. And what if there's a massive power failure, as there was a few weeks ago?
So, the most logical method of providing fire suppression cover is pumping water into static tanks. Yes, you need to do the relay pumping, but you don't have to do it to fill the static tanks as they are drawn down.
And since you're already pumping potable water up into holding tanks (that's the water that's used to flush toilets, provide water in drinking fountains, etc.), the approach in the past has normally been to simply pump water into large holding tanks for the sprinkler system, as well.
(Here's a secret... Ever been in a high rise apartment building or hotel that has a swimming pool on an upper floor? Guess what the pool is part of in many cases... The sprinkler system! It's one of the holding tanks.)
Once you have water in the holding tanks, gravity does the rest -- the water flows through standpipes to individual sprinkler heads as it's called for.
Now, imagine a plane loaded with 24,000 gallons of jet fuel kerosene crashes into the building.
I'm sure you remember the images... The planes go in one side of the building, and on the opposite side LOTS of stuff comes flying straight through the wall and down into the streets.
Remember, too, that those aircraft will impact not just a single floor, but several floors at the same time (they're taller than one floor is high), and one, if not both, planes hit at angles that transected several floors.
Immediately you have a massive breach of the pipes that supply the fire sprinklers in the areas where the jets hit, and likely in a swath right through the building to the other side. Standpipes AND individual trunk lines, on which the sprinkler heads are mounted, are destroyed, causing massive ruptures. Some likely would survive, but given that a disaster of this type was never anticipated when the building was designed, the sprinkler system is generally a large unit -- it's not branched or isolated.
The jet fuel also ignites fires over huge expanses of the floor, which means that those sprinkler heads that do survive are going to activate. They'll suppress the fire in those small areas, to some degree, but what good is that if all around that area an out-of-control fire is raging, and the sprinklers in those areas are destroyed?
So we have a unique situation. The sprinkler system was never designed to deal with such a massive fire, and it was never anticipated that the system would be catastrophically breached in so many places, rendering it largely ineffective.
And there's only a limited amount of water in the static tanks, and a large part of that is running out of the broken pipes and doing nothing to suppress the fires that are now raging across several floors.
Quite frankly, given the situation faced on September 11, I don't think any type of fire suppression system would have survived the catastrophic impact of a fully loaded jet liner going at 500 MPH.