Quentin
QUOTE: Originally posted by M.W. Hemphill 1. Sprinkler system would have to be heated to protect from freezing. I don't know how you would design a system that can distinguish between the heat of a fire and the heat of a hot exhaust stack. Maintenance requirements would be high -- and this is just one tunnel. There are 300 or so more on the UP system. Lowball cost estimate for initial installation, $100 million. Annual maintenance, probably $10 million. Actual effectivness: totally unknown, probably zero, even if you could figure out how to make it not leak, not go off on its own, not freeze and burst, not fall off the roof, not get hit by dragging equipment, not flood the tunnel, not short out the signaling system, not interfere with tight clearances, not be a target for thieves, and actualy put out a fire that's probably behind the concrete or gunite and thus inaccessible to the water spray. 2. No practical miner would buy into that idea. Explosives might temporarily snuff the flames, but they'll just relight. All three sides of the "fire triangle" would still be present: oxygen, fuel, heat. It works on an oil well because there's hardly any heat present except in the flame itself. Worse, the explosives might shatter the rock so badly the cost of recovering and relining the tunnel would escalate into the hundreds of millions of dollars. 3. They have fire cars. Have for years. The cost-benefit analysis from having staffed and prepped fire equipment ready to go, to all the places you're equally likely to need them, makes it cheaper to have the tunnel catch fire. Same problems with freezing, maintenance, people sitting around waiting for the call, and a big one called geography. It's one thing to have a fire deparment at a refinery, an installation confined to a small area and subject to lots of fires. It's another to have a fire department that covers thousands of miles of territory and might have a fire once every 20 years. The numbers are't there. 4. Why would you want to use some of the most expensive and fragile insulation known to man? Insulation doesn't stop fire. It merely delays heat transmission for a brief period, in the case of the space shuttle, about 15 minutes, in the expectation that by the end of that period the heat source is gone. "Fireproofing" in a steel-frame office building is only a method to buy time for the fire department to put out the flames, with the aid of the building's sprinker system and standpipes. As illustrated in 9/11, when the sprinkler system, standpipes, and method of reaching the fire are all toast, the fireproofing is worthless -- even if it hadn't been knocked off the structure in the first place.
RJ
"Something hidden, Go and find it. Go and look behind the ranges, Something lost behind the ranges. Lost and waiting for you. Go." The Explorers - Rudyard Kipling
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QUOTE: Originally posted by Dick_Lewis I have seen several forum entries which cite certain locomotives as having a well-known propensity to "flame" and speculating that this may have been the cause of the tunnel fire in question. (I certainly have no knowledge of the validity of such speculation.) If accurate, it would seem an engineering solution for the suspect locomotives would be in order. Or, as an alternative, assign such locomotives to territories without tunnel fire risk.
QUOTE: Originally posted by Junctionfan 4/ If they plan to use wood again, they should insulated it with the same stuff that NASA uses to keep the shuttle from burning up in the atmosphere upon re-entre.
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QUOTE: Originally posted by edblysard QUOTE: Originally posted by Junctionfan 4/ If they plan to use wood again, they should insulated it with the same stuff that NASA uses to keep the shuttle from burning up in the atmosphere upon re-entre. Junctionfan, The "insulation" on the botton of the SST isn't insulation, it is ablatement. Insulation is designed to prevent heat transfer, by absorbing the heat, and dissapating it through the entire structure, or radiating it away over time. The tiles on the leading edges and bottom of the SST are designed to burn away during re-entry. By ablating, or burning away at a fixed rate, the tiles carry the heat created by the friction of the shuttle passing through the atmosphere away in the form of a super hot gas..the "plasma" seen through the shuttle windows. They dont prevent the heat, they re-direct it. At first, the tiles were replaced every trip, but better and more efficent designs allow them to be used for two or more re-entrys with proper inspection. Fragile beyond your wildest imagination, some of them can crack if you set them down on edge, their own weight is beyond the ability of their structure to support. To show you how fragile they are, the Colombia had a leading edge tile set destroyed by a simple piece of styrofoarm insulation that broke lose from the main LOX tank, and struck the edge of the wing during launch. About the size of a standard Coleman cooler, so light my 5 year old could carry it around, yet it cracked and broke enough tiles on the wings edge so that, during re-entry, the ablatement failed, and the super hot gases from the surrounding ablatement areas entered the actual structure of the vehicle, with the result that it was destroyed. You wouldnt want to line a crock pot with this stuff, the first time you set it down hard, the linning would break. On the other hand, if you had one that was flat, you couldnt burn through it with a cutting torch, you can not create enough heat to begin the ablatement process. Ed
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