RE: H2O Microwave Criticality

["Bradshaw, Keith" <Keith.Bradshaw@nnc.co.uk>]

	<CUT>
> The main phenomenon that would limit superheating is the natural
> convection
> circulation of the water.  The cooler water in the center (self-shielding
> of
> the microwaves) would sink while the hotter water on the periphery would
> rise.  This mixing limits local superheat and promotes boiling.
> 
> I would think boiling violent enough to eject the water would be unlikely
> but possible.  Certainly very unlucky!
	<CUT>

	There have been a number of reported incidents of thick sauces,
gravy, custard and the like ejecting themselves after microwaving.
Apparently these things are more likely to superheat than water because of
the reduced convection and the coating of nucleation sites.  The kitchen's a
dangerous place!

	keith.bradshaw@nnc.co.uk


**********************************************************************
NNC Limited
Booths Hall
Chelford Road
Knutsford
Cheshire
WA16 8QZ

Country of Registration: United Kingdom
Registered Number: 1120437

This email and any files transmitted with it are confidential and 
intended solely for the use of the individual or entity to whom they   
are addressed. If you have received this email in error please notify 
the NNC system manager.
**********************************************************************
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html