Erupting Tea Pot

[n6crv]

Hello, I keep a tea pot on top of our wood stove. It is there for a couple of reason one is that if we are in a different room then where the stove is I can tell how hot the stove is getting by the whistle the tea pot is making. I have it setting on the top side of the stove. Well tonight the stove-top was down to around 200 so I added wood like I always do. It started and was JUST starting to burn good the stove-top was around 250-300 when all of a sudden the whistle part blew off and water shot everywhere about 2qts! It blew a good 4 feet and really not any steam to speak of. What happened? We have cats that like to lay around the stove and sure don't want them to get brunt with hot water. The stove was not heating up any faster then normal. The tea-pot whistle was not plugged so don't know why it blew off.
Thanks for any help/thoughts.
Don

 

[Corey]

Well, it would be pretty rare in a stovetop tea pot, but there is such a thing as superheated water. Basically, if you have a relatively pure water and a smooth pot or pan and there is just no place for the first bubbles of boiling to form - so the water can actually get above 212ºF (or what ever the local boiling temp happens to be). Then finally something sets it off and a large amount of water suddenly flashes to steam. It's more common in a microwave when you have a smooth coffee cup or bowl...heat the water a bit too hot, stick in a spoon to stir in some of your favorite java, and BOOM!! It can be very common in a laboratory setting where pure water and smooth glassware are the norm.

To avoid this, you can put some 'boiling stones' in the pot - a few bits of rock, glass, ceramic tile, or something else which is not affected by the boiling water, but has a rough surface which helps start the boiling. Once a few bubbles form, they churn the liquid enough to help more bubbles form and boiling progresses as normal.

http://www.youtube.com/watch?v=1_OXM4mr_i0

(This isn't the greatest video, but around 1:13 they stick a fork in a measuring cup of superheated water and it produces a fairly violent eplosion.)

 

[pen]

cozy is right in that it could have been super heated water.

I'd figure it was more likely that the kettle was over filled and as things heated up the whistle plugged with water and couldn't make noise until the kettle puked its contents, or else a "floater" in the water in the form of mineral deposits blocked the exit making the kettle build up pressure until it freed the blockage once the pressure was great enough in the kettle.

I think I'd set a timer instead from now on and keep the kettle on a trivet or move to a steamer which is designed for constant use.

pen

 

[n6crv]

Thank-You for the reply's. I will try putting so rocks in the bottom and see what happens. I would just take it off put the whistle works great as long as no puking.
Don

 

[Adios Pantalones]

Don't fill it to the very top. Depending on how the lid fits and where the spout connects, if the water is into the neck of the spout then there's a lot of pressure that can build up. I think that pots with spout whistles are designed to build some back pressure to make the whistle work.
You might pull off the lid and leave it ajar or off.

 

[Martin Strand III]

VERY DANGEROUS to place containers not designed
for hot stoves on hot stoves. Especially ceramic or
clay.

Years back on a Timberline insert, I placed a small
handmade ceramic pot filled with water intended to
act as a room humidifier as the water boiled off.

And it did, for a short time, until
POW! It exploded. Like a grenade,
small pieces flew throughout the room.
Lucky I was in another part of the house
and no one else was present.

Apparently, water soaked into the porous
pottery, became superheated and trapped
causing the explosion.

Lesson learned.

Aye,
Marty
Wife #2 used to say,
"You've gone from stupid to
just plain dumb."

 

[madison]

IMHO another strike for water on top of a stove.