[TheForge] Re: magnets as latches

[GHS]

Hah, when you mentioned fire doors I was thinking solvent and boiler 
rooms. <G> No wonder I couldn't figure out why you wanted magnets. (and 
BIG magnets they would be)

That will teach me to post before the coffee kicks in.

Mike Graf

Roger Olsen wrote:

> In my county code is all fireplaces must have closeable doors,  they do not have to
> be air tight.  Any latch system is OK as far as the inspector is concerned.
> _____________________________
> 
> GHS wrote:
> 
> 
>>Also, and perhaps more to the point, will the fire codes allow them?
>>
>>Mike Graf
>>
>>Roger Olsen wrote:
>>
>>>Let me try asking the question this way________do any of you have actual
>>>experience using magnets for a closing system on firedoors?  I am not asking
>>>those of you who have guesses or assumptions or opinions, only those of you who
>>>have actually used them and what you found______did the doors latch the same
>>>two years from day one or did they loose a lot if not all of their magnetic
>>>qualities.
>>>
>>>Thanks,
>>>R Olsen
>>>__________________________
>>>
>>>Steve Smith wrote:
>>>
>>>
>>>
>>>>I don't have a clue, Roger. I did find a list of Curie point
>>>>temperatures for different materials. Here are a few (in degrees
>>>>Kelvin--subtract 273 and you have Centigrade):
>>>>Iron 1043
>>>>Cobalt 1388
>>>>Nickle 627
>>>>source: http://www.nationmaster.com/encyclopedia/ferromagnetism
>>>>
>>>>etc. So your question is good, how soon do you see effects? It also
>>>>looks like you have a huge effect in the actual temp by what alloy
>>>>you're magnet is made of. I don't think this helps, just more info.
>>>>
>>>>Steve Smith
>>>>
>>>>Roger Olsen wrote:
>>>>
>>>>
>>>>
>>>>>So I assume the higher the heat the faster the magnetic loss but when does
>>>>>the affect kick in?  100 degrees________300 degrees_________500
>>>>>degrees________700 degress?
>>>>>
>>>>>Does anyone know the answer to this?
>>>>>
>>>>>R. Olsen
>>>>>_______________________
>>>>>
>>>>>Bruce Freeman wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>Clearly, when steel goes non-magnetic, if the steel WERE a magnet it
>>>>>>wouldn't be afterwards.
>>>>>>
>>>>>>However, any heating or hammering will reduce or destroy the magnetic
>>>>>>properties of a steel magnet.
>>>>>>
>>>>>>If using a magnet as part of a door latch:
>>>>>>
>>>>>>First, be aware that those rare earth magnets can be VERY strong.
>>>>>>Think pinch-points when using them in a design.
>>>>>>
>>>>>>Second, you may want to move the magnet itself away from the heat.
>>>>>>Imagine, for example, using a horseshoe magnet as the handle on a hot
>>>>>>door.  The cooler handle will be less likely to lose its magnetic
>>>>>>properties.  But if constructed correctly, this remote handle could be
>>>>>>an effective latch for the door, since the magnetic forces will follow
>>>>>>the path of the steel.  (Constructed incorrectly, there would be no
>>>>>>magnetism to latch the door, however.   Avoid a complete loop.  Think:
>>>>>>"horseshoe" shape.)
>>>>>>
>>>>>>Bruce
>>>>>>NJ
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>>>erik at methow.com 5/13/2004 12:22:50 PM >>>
>>>>>>
>>>>>>Hey Andy,
>>>>>>
>>>>>>Ask your friend one other thing about magnets.  I wonder about heat, at
>>>>>>what
>>>>>>point does it drain a magnet of its magic affects?   I have never used
>>>>>>them on
>>>>>>fire doors but I know many have.  I have considered using them in the
>>>>>>past and
>>>>>>I am sure I will again in the future.
>>>>>>
>>>>>>If I did I would use the 'Rare Earth Magnets' sold by Lee Valley and
>>>>>>others as
>>>>>>well.  They seem to be about 10 times stronger than the radio shack
>>>>>>type
>>>>>>magnets.
>>>>>>
>>>>>>Roger Olsen
>>>>>>__________________________________
>>>>>>
>>>>>>Gladish Family wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>>1. I have a number of assorted magnets used for set-ups, mock ups
>>>>>>
>>>>>>and
>>>>>>
>>>>>>
>>>>>>
>>>>>>>>the like...should they be stored separately, carefully aligned
>>>>>>>>north/south, to retain max  pull ( suck?) or is it not a problem
>>>>>>
>>>>>>just to
>>>>>>
>>>>>>
>>>>>>
>>>>>>>>toss them in a box with their friends?
>>>>>>>
>>>>>>>My understanding is that magnets are manufactured by applying
>>>>>>
>>>>>>overwhelming
>>>>>>
>>>>>>
>>>>>>
>>>>>>>magnetic fields (i.e. really really huge!) to a previously neutral
>>>>>>
>>>>>>chunk of
>>>>>>
>>>>>>
>>>>>>
>>>>>>>metal, and that heat or overwhelming magnetic force are the only ways
>>>>>>
>>>>>>that
>>>>>>
>>>>>>
>>>>>>
>>>>>>>magnets lose their pull, other than physical deterioration.
>>>>>>>I have a friend who sells magnets for a living- I'll ask him.
>>>>>>>Andy G.
>>>>>>>
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>>>>>
>>>>>
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>>>>
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