Warning: Boiling Water

rondetto

*Microwaving Water!
*
A 26-year old man decided to have a cup of coffee. He took a cup of water
and put it in the microwave to heat it up (something that he had done
numerous times before). I am not sure how long he set the timer for, but he
wanted to bring the water to a boil. When the timer shut the oven off, he
removed the cup from the oven. As he looked into the cup, he noted that the
water was not boiling, but suddenly the water in the cup 'blew up' into his
face. The cup remained intact until he threw it out of his hand, but all
the water had flown out into his face due to the build-up of energy. His
whole face is blistered and he has 1st and 2nd degree burns to his face
which may leave scarring.

He also may have lost partial sight in his left eye. While at the hospital,
the doctor who was attending to him stated that this is a fairly common
occurrence and water (alone) should never be heated in a microwave oven. If
water is heated in this manner, something should be placed in the cup to
diffuse the energy such as a wooden stir stick, tea bag, etc, (nothing
metal).
*
General Electric's Response:
*
Thanks for contacting us; I will be happy to assist you. The e-mail that
you received is correct. Microwaved water and other liquids do not always
bubble when they reach boiling point. They can actually get superheated and
not bubble at all. The superheated liquid will bubble up out of the cup
when it is moved or when something like a spoon or tea bag is put into it.

To prevent this from happening and causing injury, *do not heat* any liquid
for more than *two minutes per cup*. After heating, let the cup stand in
the microwave for* thirty seconds* before moving it or adding anything into
it.

Here is what our local science teacher had to say on the matter: 'Thanks
for the microwave warning. I have seen this happen before. It is caused by
a phenomenon known as super heating. It can occur any time water is heated
and *will particularly occur* if the vessel that the water is heated in is
new, or when heating a small amount of water *(less than half a cup*).

What happens is that the water heats faster than the vapour bubbles can
form. If the cup is very new, then it is unlikely to have small surface
scratches inside it that provide a place for the bubbles to form. As the
bubbles cannot form and release some of the heat that has built up, the
liquid does not boil, and the liquid continues to heat up well past its
boiling point.

What then usually happens is that the liquid is bumped or jarred, which is
just enough of a shock to cause the bubbles to rapidly form and expel the
hot liquid. The rapid formation of bubbles is also why a carbonated
beverage spews when opened after having been shaken.'
*
If you pass this on*, you could very well save someone from a lot of pain
and suffering

barbara12

Gosh Ron
That is very interesting, I sometimes boil water in the microwave , one thing I don't like seeing is someone warming babies milk in there, has it carrys on warming when taken out
I will take heed and stop boiling my water in there... :shock:

valval

i always make sure to stir liquid before removal if possible as have seen this on a news program when microwaves first came out and lots of people did not realize how dangerous it can be same with milk

mellman01

One thing you should always watch out for is a layer of super heated steam that can build up under any layer of cling film in a microwave oeven, got had before by this so I NEVER use my hand to start to pull off the film as as soon as you open up the dish to air the steam comes out the opening and bingo burnt flipper.

georgie66

blimey interesting reading that never knew that could happen
glad now i never got a microwave..
georgie