Squeaky Sound Of A Kettle After Pouring Water

[kubofal]

When I rather quickly poured water from a kettle and than I wanted to put it back onto it's stand I heard a short, squeaky sound. I recorded that phenomenon and thought about hypothesis. I was wondering if you could comment on my hypothesis and help me explain this sound. Thank you!

Here is my hypothesis: http://postimg.org/image/fcf89vw8v/

Here is recorded phenomenon :

[J.C.MacSwell]

Sounds like an oil canning effect from a reversal of pressure or possibly temperature on the almost flat bottom of the kettle.

[DrP]

You poured quite fast from a nearly empty kettle as it was boiling, so the element is still going to be very hot... You tipped out nearly all the water, so the element had a chance to be free from the water for a second or too - I reckon it dried out. When the kettle is righted again a small amount of water that did not drain out of the kettle met back with the, now dry, hot element and boiled off to steam in an instantaneous squeak.

[Strange]

Is there limescale on the element? That might make the effect greater - more nucleation of small bubbles; possibly bubbles being formed under layer of scale and forcing their way out.

[kubofal]

Sounds like an oil canning effect from a reversal of pressure or possibly temperature on the almost flat bottom of the kettle.

Hi! Thanks for your reply.

I looked at a bottom of the kettle. It is really robust and flat, no signs of oil canning.

I am including a picture of the bottom of the kettle: http://imgur.com/gallery/7C55dUP/new

You poured quite fast from a nearly empty kettle as it was boiling, so the element is still going to be very hot... You tipped out nearly all the water, so the element had a chance to be free from the water for a second or too - I reckon it dried out. When the kettle is righted again a small amount of water that did not drain out of the kettle met back with the, now dry, hot element and boiled off to steam in an instantaneous squeak.

Thanks for reply! I did experiment where i did not righ kettle so water did not met back with the hot element.

Here it is:

 

Is there limescale on the element? That might make the effect greater - more nucleation of small bubbles; possibly bubbles being formed under layer of scale and forcing their way out.

Also thank you for replying! There is no limescale on the bottom.

Picture of the bottom of the kettle: http://imgur.com/gallery/7C55dUP/new

[imatfaal]

its not the sound of the heat activated switch popping back into rest-state is it?

[kubofal]

its not the sound of the heat activated switch popping back into rest-state is it?

Hi! Thank you for replying. I am pretty sure it is not. There is only a heat activated switch for announcing boiling water. You can hear it in the begging of the videos.

[Strange]

Or strain caused by different parts of the metal cooling at different rates?

[kubofal]

Or strain caused by different parts of the metal cooling at different rates?

Well, it could be helpful to find out if plastic kettles make that sound too.

But anyway, I don't think there could become necessary difference in temperatures. Bottom of the kettle is still heated by element and in upper part of the kettle is boiling water. Difference between temperatures of outer and inner parts is also out because still kettle without pouring doesn't make that sound.

[imatfaal]

Hi! Thank you for replying. I am pretty sure it is not. There is only a heat activated switch for announcing boiling water. You can hear it in the begging of the videos.

 

I didn't say it was the cut-off activating - I was thinking it was the cutoff resetting after cooling

 

The heat-activated cutoff switch is at rest-state normally - the steam heats it up and it changes state which then stops the power (that is at the beginning) and flicks the kettle to auto-off, then after a few seconds of cooling the switch flicks back to off to allow the kettle to be reboiled.

 

It is a very weird sound and isn't anything like my kettle resetting the thermoswitch - but then my kettle doesn't have such a positive load click for the initial trip of the thermoswitch. Remember that sone of these switches use bimetallic strips under pressure that flicks back - and the noise could be the ping of metal flicking back

[J.C.MacSwell]

Hi! Thanks for your reply.

I looked at a bottom of the kettle. It is really robust and flat, no signs of oil canning.

I am including a picture of the bottom of the kettle: http://imgur.com/gallery/7C55dUP/new

Thanks for reply! I did experiment w

 

It looks like it may have a dent in it at about 11 o'clock. Can you push on the bottom of it?

[arc]

The noise is produced when the hot water contacts the general area around the spout. This is just a portion of the total area that forms the tapered and formed metal opening that is itself encased within the plastic integrated handle that forms the actual opening into the interior.

 

These two very different materials expand when heated at very different rates of expansion, with the metal container producing an outward radial movement as the hot water expands the area of the spout. The less thermally reactive plastic rim, that is integrated to the handle, is fitted tight enough to prevent leakage and would no doubt cause the metal to pop as it forces its way past the tight fitting slot that it is encased in.

 

I would bet you could reproduce the sound when the pot is cool by just heating the spout area with an electric heat gun or even a hair dryer.

Edited September 25, 2015 by arc