5 ms·

Do they burn...?

sliverstorm 16y ago
It might seem like a bit of a trollish question, but I'm wondering the same thing. I am trying to think of benefits to wooden ladders; they are heavy, easier to damage, harder to make. Probably an incredible challenge to make extendable ones too. The one upside beyond cosmetics I can think of is they probably don't get hot the way metal does. edit: OK, I finished watching the video, I understand now. So it's not that they are necessarily better than metal, but they are necessary in SF.
- MichaelApproved 16y ago
  They are necessary because of the large amount of hanging electrical wires SF has.
  - ars 16y ago
    Why is it wood vs aluminium? What about fiberglass? Doesn't conduct, lighter, and doesn't fail suddenly in heat.
    - britta 16y ago
      See the article at http://articles.sfgate.com/2007-06-25/bay-area/17249021_1_wooden-ladders-aluminum-or-fiberglass-san-francisco-s-fire-shop http://articles.sfgate.com/2007-06-25/bay-area/17249021_1_wo... - They don't conduct electricity like aluminum or wet fiberglass ladders do....Aluminum or fiberglass, when it gets too hot, it gets soft; it will actually fold over without any warning."
    - msbarnett 16y ago
      Too light = bad stability in high winds, like those common in San Francisco.
  - sliverstorm 16y ago
    does aluminum start to conduct at high voltage? Normally the oxide layer makes it a bad conductor.
Simucal 16y ago
They mentioned in the video that they apply varnish to make them less flammable. So, they do burn but perhaps not as easily as you would think.
pinaceae 16y ago
wood is far more safer when exposed to heat than metal. while wood starts to burn on the outside it turns into coal, which effectively seals the remaining wood core from oxygen - preventing (for a while) further structural loss. this is taken into consideration when sizing wooden structures in buildings. metal on the other hand loses structural integrity when exposed to heat shockingly fast. the wtc towers showcased this effect quite publicly. experienced firefighters prefer to deal with fire in wooden structures than in metal ones. they can predict how long a wooden roof structure will take till collapse quite well, while a metal structure is a nightmare. so, flammability and structural integrity under heat are two different things. non-intuitive for most non-engineers, hence the retarded wtc discussions. in SF's case they use wood because of its function as an isolator.
- MichaelApproved 16y ago
  >>metal on the other hand loses structural integrity when exposed to heat shockingly fast. the wtc towers showcased this effect quite publicly. but isn't that at extremely high temperature? Wouldn't that same amount of heat burn wood far faster than it would damage metal? The wtc towers were exposed to jet fuel and beaten by a jetliner slamming into the building. Also, the metal beams in the wtc towers were made of steel while ladders are made of aluminum.
  - evgen 16y ago
    For a straight-up failure test, yes. Try exposing wood and metal to fire, then cool it, then expose it again, etc. You can tell visually when the wood is likely to fail much easier than the metal.
  - sokoloff 16y ago
    Aluminum (in most alloys) loses significant strength in the 400-500*F range. By 600F, Al alloys are very weak. http://www.burnsstainless.com/yieldstrength.aspx http://www.burnsstainless.com/yieldstrength.aspx
    - baguasquirrel 16y ago
deleted 16y ago
[deleted]
JanezStupar 16y ago
Like the other said. If you build it from right type of wood prepared the right way - those things are incredible. They are insulators - helping with electricity AND heat. They are predictable... Wood is an awesome material - but it takes time and expertise to do it right - thus making it expensive. But nevertheless the highest quality and style items are still made of wood - it just ain't cheap. Think: furniture, insulation, windows, doors, floors, stairs... Hell wooden shingle roofs can and do last over hundred years if prepared properly.

Do they burn...?

It might seem like a bit of a trollish question, but I'm wondering the same thing. I am trying to think of benefits to wooden ladders; they are heavy, easier to damage, harder to make. Probably an incredible challenge to make extendable ones too. The one upside beyond cosmetics I can think of is they probably don't get hot the way metal does. edit: OK, I finished watching the video, I understand now. So it's not that they are necessarily better than metal, but they are necessary in SF.

MichaelApproved 16y ago
They are necessary because of the large amount of hanging electrical wires SF has.
- ars 16y ago
  Why is it wood vs aluminium? What about fiberglass? Doesn't conduct, lighter, and doesn't fail suddenly in heat.
  - britta 16y ago
    See the article at http://articles.sfgate.com/2007-06-25/bay-area/17249021_1_wooden-ladders-aluminum-or-fiberglass-san-francisco-s-fire-shop http://articles.sfgate.com/2007-06-25/bay-area/17249021_1_wo... - They don't conduct electricity like aluminum or wet fiberglass ladders do....Aluminum or fiberglass, when it gets too hot, it gets soft; it will actually fold over without any warning."
  - msbarnett 16y ago
    Too light = bad stability in high winds, like those common in San Francisco.
- sliverstorm 16y ago
  does aluminum start to conduct at high voltage? Normally the oxide layer makes it a bad conductor.

Simucal 16y ago

They mentioned in the video that they apply varnish to make them less flammable. So, they do burn but perhaps not as easily as you would think.

pinaceae 16y ago

wood is far more safer when exposed to heat than metal. while wood starts to burn on the outside it turns into coal, which effectively seals the remaining wood core from oxygen - preventing (for a while) further structural loss. this is taken into consideration when sizing wooden structures in buildings. metal on the other hand loses structural integrity when exposed to heat shockingly fast. the wtc towers showcased this effect quite publicly. experienced firefighters prefer to deal with fire in wooden structures than in metal ones. they can predict how long a wooden roof structure will take till collapse quite well, while a metal structure is a nightmare. so, flammability and structural integrity under heat are two different things. non-intuitive for most non-engineers, hence the retarded wtc discussions. in SF's case they use wood because of its function as an isolator.

MichaelApproved 16y ago
>>metal on the other hand loses structural integrity when exposed to heat shockingly fast. the wtc towers showcased this effect quite publicly. but isn't that at extremely high temperature? Wouldn't that same amount of heat burn wood far faster than it would damage metal? The wtc towers were exposed to jet fuel and beaten by a jetliner slamming into the building. Also, the metal beams in the wtc towers were made of steel while ladders are made of aluminum.
- evgen 16y ago
  For a straight-up failure test, yes. Try exposing wood and metal to fire, then cool it, then expose it again, etc. You can tell visually when the wood is likely to fail much easier than the metal.
- sokoloff 16y ago
  Aluminum (in most alloys) loses significant strength in the 400-500*F range. By 600F, Al alloys are very weak. http://www.burnsstainless.com/yieldstrength.aspx http://www.burnsstainless.com/yieldstrength.aspx
  - baguasquirrel 16y ago

deleted 16y ago

[deleted]

JanezStupar 16y ago

Like the other said. If you build it from right type of wood prepared the right way - those things are incredible. They are insulators - helping with electricity AND heat. They are predictable... Wood is an awesome material - but it takes time and expertise to do it right - thus making it expensive. But nevertheless the highest quality and style items are still made of wood - it just ain't cheap. Think: furniture, insulation, windows, doors, floors, stairs... Hell wooden shingle roofs can and do last over hundred years if prepared properly.