[TheForge] Re: magnets as latches

[Roger Olsen]

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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