You Could
Avoid an Accident
By Col. Riaz Jafri
(Retd)
Rawalpindi, Islamabad
My 26-year old son 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
told me he wanted to bring the water to a boiling
point. 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 instantly 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 buildup of energy. His whole face is
blistered and he has first and second degree burns
to his face which may leave scarring. He may also
have lost partial sight in his left eye.
While at the hospital, the doctor who was attending
to him stated that this is fairly common occurrence
and water (alone) should never be heated in a
microwave oven. If water is heated in this manner,
something such as a wooden stir stick, tea bag,
etc. should be placed in the cup to defuse the
energy. It is however a much safer choice to boil
the water in a kettle.Please pass this information
on to friends and family.
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 the 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. I hope this helps.
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 anytime water is heated and will
particularly occur if the vessel that the water
is heated in is new, or when one is heating a
small amount of water (less than half a cup).
“What happens is that the water heats faster
than the vapor 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.”- Shahid.
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