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Post by silverdragon on Dec 10, 2016 13:41:20 GMT
If Everyone in a Skyscraper...
Flushed the toilet at the same time, the building would collapse.
It is suggested that the weight of "all that water" in free-flow down the sewers would either back up the toilets on the lower floors, or just vibrate the pipes "enough", or the sheer weight of the water alone would crate havoc?..
BTW, I know the answer is a lot simpler and this one could be busted by physics alone, but well, why not have this as a full scale segment on the show if it ever comes back in any form.
The suggested answer I believe to be true is that the "Four inch pipe" that we all know as sewerage drains are designed in such a way that they would choke back excessive flow in such a situation and that would prevent problems.
Could the four-inch pipe at the bottom of the skyscraper hold in such pressure of a back-up of maybe 20 storeys of flow?... now that bit I aint sure about, but, I suspect there is an easy answer, and yes, yes it could?..
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Post by silverdragon on Dec 10, 2016 13:45:55 GMT
If Everyone in a Skyscraper...
Express elevator theory.
So if Everyone..
...caught an elevator down at the same time and for some reason the doors at the bottom floor were left open, the sudden rush of air into the bottom floor from all of the elevators arriving at the same time, would "blow the bloody doors off" the front of the building...
I believe modern elevators are designed aerodynamically with cones at the top and base of the lift to ease air past the "box" shape of the lift to prevent express elevators creating such a huge pressure wave?...
I also believe modern lift shafts are wider than you think to allow air to go around the lift to stop this happening.
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Post by silverdragon on Dec 10, 2016 13:48:09 GMT
If Everyone in a Skyscraper...
Ran in unison from one side to the other, and back again, it would create a swing in the building the same as a high wind, or earthquake...
On those buildings with "trick" anti-earthquake foundations that allow it to move a bit, that may also make the building move sideways by a foot?..
Plausible?..
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Post by GTCGreg on Dec 10, 2016 17:52:26 GMT
If Everyone in a Skyscraper... Flushed the toilet at the same time, the building would collapse. It is suggested that the weight of "all that water" in free-flow down the sewers would either back up the toilets on the lower floors, or just vibrate the pipes "enough", or the sheer weight of the water alone would crate havoc?.. BTW, I know the answer is a lot simpler and this one could be busted by physics alone, but well, why not have this as a full scale segment on the show if it ever comes back in any form. The suggested answer I believe to be true is that the "Four inch pipe" that we all know as sewerage drains are designed in such a way that they would choke back excessive flow in such a situation and that would prevent problems. Could the four-inch pipe at the bottom of the skyscraper hold in such pressure of a back-up of maybe 20 storeys of flow?... now that bit I aint sure about, but, I suspect there is an easy answer, and yes, yes it could?.. I'm sure the mechanical engineers were smart enough to figure this one out. But even if they didn't, the pressure in that 4" pipe isn't going to ever get that high. The water would simply flow out of the toilets on the lower floors. |
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Post by GTCGreg on Dec 10, 2016 17:58:29 GMT
If Everyone in a Skyscraper... Express elevator theory. So if Everyone.. ...caught an elevator down at the same time and for some reason the doors at the bottom floor were left open, the sudden rush of air into the bottom floor from all of the elevators arriving at the same time, would "blow the bloody doors off" the front of the building... I believe modern elevators are designed aerodynamically with cones at the top and base of the lift to ease air past the "box" shape of the lift to prevent express elevators creating such a huge pressure wave?... I also believe modern lift shafts are wider than you think to allow air to go around the lift to stop this happening. Never saw an elevator cab with cones on the ends. But as you suggest, the elevator shaft isn't sealed around the car. And don't forget that there is also room in the shaft for the counterweight that is also pushing air in the opposite direction. |
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Post by GTCGreg on Dec 10, 2016 18:06:09 GMT
If Everyone in a Skyscraper... Ran in unison from one side to the other, and back again, it would create a swing in the building the same as a high wind, or earthquake... On those buildings with "trick" anti-earthquake foundations that allow it to move a bit, that may also make the building move sideways by a foot?.. Plausible?.. It would have to be more than just running. It would be the sudden stopping that would cause a sideways force on the building. I just don't see the weight of a couple of hundred people per floor being anywhere near the windloading design limitations of the building. The Sears Tower in Chicago, (now Willis Tower, although no one in Chicago will call it that) sways about 6" on a windy day. That swaying can be felt inside the building. patch.com/illinois/chicago/freaky-willis-tower-sway-video-0 |
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Post by the light works on Dec 11, 2016 2:46:18 GMT
If Everyone in a Skyscraper... Express elevator theory. So if Everyone.. ...caught an elevator down at the same time and for some reason the doors at the bottom floor were left open, the sudden rush of air into the bottom floor from all of the elevators arriving at the same time, would "blow the bloody doors off" the front of the building... I believe modern elevators are designed aerodynamically with cones at the top and base of the lift to ease air past the "box" shape of the lift to prevent express elevators creating such a huge pressure wave?... I also believe modern lift shafts are wider than you think to allow air to go around the lift to stop this happening. Never saw an elevator cab with cones on the ends. But as you suggest, the elevator shaft isn't sealed around the car. And don't forget that there is also room in the shaft for the counterweight that is also pushing air in the opposite direction. elevators really don't go very fast, and the shafts aren't sealed very tight. the effect on the air column would be similar to a truck going through a tunnel. |
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Post by the light works on Dec 11, 2016 2:52:56 GMT
If Everyone in a Skyscraper... Flushed the toilet at the same time, the building would collapse. It is suggested that the weight of "all that water" in free-flow down the sewers would either back up the toilets on the lower floors, or just vibrate the pipes "enough", or the sheer weight of the water alone would crate havoc?.. BTW, I know the answer is a lot simpler and this one could be busted by physics alone, but well, why not have this as a full scale segment on the show if it ever comes back in any form. The suggested answer I believe to be true is that the "Four inch pipe" that we all know as sewerage drains are designed in such a way that they would choke back excessive flow in such a situation and that would prevent problems. Could the four-inch pipe at the bottom of the skyscraper hold in such pressure of a back-up of maybe 20 storeys of flow?... now that bit I aint sure about, but, I suspect there is an easy answer, and yes, yes it could?.. the tallest building I have worked alongside the plumbers in was 4 stories. at that height, the drains can survive being filled to the top and then released all at once. of course, they also have to seal the drains in the bathtubs to prevent water leaking out - and the pressure will blow an improperly installed seal out of the drain. it seems to me this actually is one that could be investigated to see if a significant dump of water in a tall building can back up enough to backflow drains in the bottom. keeping in mind, the toilets would have to be tank style toilets, otherwise, the "dump" would be limited to what the supply lines could deliver. |
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Post by silverdragon on Dec 11, 2016 6:51:09 GMT
Elevators on skyscrapers, think Burj Khalifa or Petronas Towers   Modern day half-mile high type things, and the express elevators that do floors-per-second. Those express elevators have the cones on them. |
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Post by the light works on Dec 11, 2016 15:21:50 GMT
Elevators on skyscrapers, think Burj Khalifa or Petronas Towers Modern day half-mile high type things, and the express elevators that do floors-per-second. Those express elevators have the cones on them. 1 floor per second is in the neighborhood of 8 miles per hour. as for the lift cars themselves, the regular lift cars appear to have the usual flat ends. the "shuttle lifts" which would be the high speed lifts to get you to the bottom of the upper level lift section, apparently are a state secret, since google returns no pictures of them. I would presume they would have aerodynamics as much to reduce wind noise as for anything else. |
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Post by silverdragon on Dec 12, 2016 6:03:27 GMT
OhCr@p, even my own "Google-foo" has come up a bust on this one...
You are going to have to take it from me that they are now designing elevators with aerodynamic cones on the top and bottom to ease air-flow...
Not even I can find this stuff on the net, but I know it exists?.
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Post by ponytail61 on Dec 12, 2016 6:41:16 GMT
OhCr@p, even my own "Google-foo" has come up a bust on this one... You are going to have to take it from me that they are now designing elevators with aerodynamic cones on the top and bottom to ease air-flow... Not even I can find this stuff on the net, but I know it exists?. Here ya go www.toshiba-elevator.co.jp/elv/infoeng/products/ultrahigh/index.htmlIt's not just your google foo, took me awhile to find it. |
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Post by silverdragon on Dec 12, 2016 10:38:56 GMT
 AHHHHH... TAIPEI 101.... Exactly the building I "watched" being built on the documentary that was talking about the elevators... Thanks Pony, I "Owe you one" for that. |
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Post by the light works on Dec 12, 2016 15:01:57 GMT
the picture says aerodynamic shape to reduce wind shear.
this says to me the nose cones are to give a smoother and quieter ride to the elevator car, not to prevent the elevator shaft working as a fire piston.
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Post by silverdragon on Dec 13, 2016 7:13:26 GMT
the picture says aerodynamic shape to reduce wind shear. this says to me the nose cones are to give a smoother and quieter ride to the elevator car, not to prevent the elevator shaft working as a fire piston. Exactly, it reduces the pressure build up below the leading "edge", being that the average box is the worst aerodynamic shape you can get unless its flying pointy-bit first... And if a lift is flying that way, you are in a whole world of trouble anyway?. |
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Post by the light works on Dec 13, 2016 14:39:10 GMT
the picture says aerodynamic shape to reduce wind shear. this says to me the nose cones are to give a smoother and quieter ride to the elevator car, not to prevent the elevator shaft working as a fire piston. Exactly, it reduces the pressure build up below the leading "edge", being that the average box is the worst aerodynamic shape you can get unless its flying pointy-bit first... And if a lift is flying that way, you are in a whole world of trouble anyway?. we have that situation on our quick response pickups. the light bar is flat on the faces, and above 35 MPH, it sounds like you are driving about 75. - speaking of wind noise, not engine/tire noise. |
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Post by WhutScreenName on Dec 13, 2016 15:50:06 GMT
If Everyone in a Skyscraper... Express elevator theory. So if Everyone.. ...caught an elevator down at the same time and for some reason the doors at the bottom floor were left open, the sudden rush of air into the bottom floor from all of the elevators arriving at the same time, would "blow the bloody doors off" the front of the building... I believe modern elevators are designed aerodynamically with cones at the top and base of the lift to ease air past the "box" shape of the lift to prevent express elevators creating such a huge pressure wave?... I also believe modern lift shafts are wider than you think to allow air to go around the lift to stop this happening. The weight wouldn't be an issue... as TLW said in a post, the toilets would have to be ones with a tank on them in order to get the water flow, otherwise it would be an issue of supply lines. If the water is already in the tank, then flushing isn't going to cause 'new' weight, it's simply going to shift it to the lines... and if everyone flushed at the same time, the water would be displaced at the same time... a better test would be to start at the top, and flush the lower floors sequentially, IE starting at the top, and then a split second later the nect floor down, and so on until the bottom... this creating the 'wave' effect... |
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Post by the light works on Dec 13, 2016 16:49:36 GMT
If Everyone in a Skyscraper... Express elevator theory. So if Everyone.. ...caught an elevator down at the same time and for some reason the doors at the bottom floor were left open, the sudden rush of air into the bottom floor from all of the elevators arriving at the same time, would "blow the bloody doors off" the front of the building... I believe modern elevators are designed aerodynamically with cones at the top and base of the lift to ease air past the "box" shape of the lift to prevent express elevators creating such a huge pressure wave?... I also believe modern lift shafts are wider than you think to allow air to go around the lift to stop this happening. The weight wouldn't be an issue... as TLW said in a post, the toilets would have to be ones with a tank on them in order to get the water flow, otherwise it would be an issue of supply lines. If the water is already in the tank, then flushing isn't going to cause 'new' weight, it's simply going to shift it to the lines... and if everyone flushed at the same time, the water would be displaced at the same time... a better test would be to start at the top, and flush the lower floors sequentially, IE starting at the top, and then a split second later the nect floor down, and so on until the bottom... this creating the 'wave' effect... it would be an interesting thing to study; and by "study" I mean have someone with more time and money than me do experiments on. my thinking would be to assemble a structire, maybe 10 stories tall, with transparent pipes, and two or three toilets per floor. maybe one setup with pipes sized to current codes, and another with pipes sized for early codes; and possibly with one sized to replicate old clogged pipes. (make it so you can change out the soil stack, which is the critical pipe.) |
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Post by silverdragon on Dec 14, 2016 8:07:31 GMT
I am thinking more on the toilet problem of say 30ft of water has a lot of pressure, if that was 300ft of water, all at the same time, on the sewer pipes, could the lower sections of pipe hold that much pressure?..
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Post by GTCGreg on Dec 14, 2016 14:29:32 GMT
I am thinking more on the toilet problem of say 30ft of water has a lot of pressure, if that was 300ft of water, all at the same time, on the sewer pipes, could the lower sections of pipe hold that much pressure?.. If a 300ft vertical pipe was filled to the top with water, the pressure at the bottom would be about 150psi. I would think the problem would be dropping a slug of water 300 feet and what happens when it hits the bottom. More of a water hammer problem than a pressure problem. A lot of this is already taken into consideration in the design. But I'm sure they have maximum load numbers. Exceed those design parameters and who knows. Here's more on the plumbing design considerations of high-rise buildings if anybody is interested. www.newcomb-boyd.com/publications-presentations-seminar-notes/high-rise-plumbing-design-its-all-the-same-right/ |
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