Date:         Fri, 24 Sep 2010 07:31:26 -0500
Reply-To:     John Rodgers <inua@CHARTER.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Rodgers <inua@CHARTER.NET>
Subject:      Re: it's Friday, she blew the microwave up
Comments: To: Rob <becida@COMCAST.NET>
In-Reply-To:  <vanagon%2010092404413859@GERRY.VANAGON.COM>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

  Water can be strange stuff. We need it to survive, so we drink it, yet
it is the most corrosive/erossive stuff on the planet.

Water being chilled to the freeze point, shrinks until 4C or 39F, then
begins to expand as it chils further to the freeze point.

Water in a cup, left un-disturbed,  can be super cooled below freeze
point of 32F, yet remain in a liquid state,  then when jiggled the
tiniest bit, instantly turns to ice.

Water in a cup, left undisturbed, when heated in a microwave,  can
become super-heated - that is, get hotter than boiling temperature of
212F. Then when it is jiggled the tiniest bit -  being hotter than
boiling point, instantly turns to steam. Never, ever, heat a drink in a
microwave, and immediately after it shuts off reach in and grab the cup.
You may be grabbing a steam explosion. Give it a couple of minutes.

It is the latter principle, along with a couple of other things, that
applies to the exploding egg. The egg shell acts as a containment
vessel, and the egg heats so rapidly from the inside out that the
temperature rises about the boiling point of water before expansion and
conversion has time to take place in a slower manner to release the
pressure. Suddenly the egg cracks, releasing the pressure, the pressure
drop allows the water to convert to steam instantly, and steam expands
rapidly. Result: you have a pretty powerful steam explosion, sufficient
to blow open the microwave door.

Can the door be fixed? Dunno.

John Rodgers
Clayartist and Moldmaker
88'GL VW Bus Driver
Chelsea, AL
Http://www.moldhaus.com


On 9/24/2010 3:30 AM, Rob wrote:
> A daughter tried to hard boil an egg in the microwave oven and blew
> it up. The way I heard it she put the egg in and turned it on, later
> BOOM the door blew open and the microwave didn't work anymore.
> When I got home I looked at it and one of the lathes is broken.
>
> I'd never heard of such a thing but I thought if any group of people
> could deal with this or explain it the folks on the Vanagon list could.
>
> The egg caused the door to blow open on a modern microwave oven and
> break a latch in the process?  Any thoughts this Friday?
>
>
>
> Rob
> becida@comcast.net
>
>