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[DPRG] ceramic magnets

Subject: [DPRG] ceramic magnets
From: Gordon McComb gmccomb at gmccomb.com
Date: Sat Dec 28 21:56:00 CST 2002

My only experience with a similar product was a magnetic mixer used for
chemicals (in my case, photographic processing chemicals). I don't think
the impeller was even a magnet, but just a ceramic-coated piece of steel --
it was quite heavy. I likened the thing to a white Good 'n Plenty.

You can readily test if the impeller is a magnet of course, but I imagine
the only way to determine if it's a coated magnet is to saw it in half. I
think that'll let all the remaining magnetism leak out, though, so be careful!

-- Gordon

At 09:13 PM 12/28/2002 -0600, you wrote:
>There could be points of difference there on that subject,
>but in my case they do after a fashion.
>For my salt water aquarium, I use various filter systems with different
>kinds of water pumps.
>I discovered that after a year or so, the ceramic magnet impeller starts to
>rust and swell/expand causing the impellor to jam against the housing and
>stop. So once a year I have to replace the magnetic impellor units. If the
>old one hasn't started rusting and swelling, leaving it out in the air for a
>while usually does the trick and they start rusting and swelling and
>breaking apart.
>The problem is determining if the magnetic impellor is a real ceramic
>composite or simply a ceramic coated magnet. After they go bad it's hard to
>tell as they sort of disintegrate before your eyes. Some impellors seem to
>work longer as long as the impellor never stops spinning as the centrifugal
>force keeps the water out, at least until you stop it for a while.
>But then maybe fresh water isn't as hard on the impellors as the corrosive
>salt water is.
>Basically, if air or moisture can get into the ferrous magnetic material,
>you'll get rust or oxidation to take place.

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