What happens if you boil water in this situation?

[Agile]

Don't try this at home - by blanking the pressure relieve valve and adding more weights to the top of the pressure cooker you could create your situation for real, but the pressure cooker WILL explode at some point producing LETHAL metal fragments and LETHAL superheated steam. Your kitchen walls are not built to withstand this sort of explosion and would probably collapse. THis is why pressure cookers have TWO safety systems.

Actually that does not happen!

Firstly they have a little rubber bung with a metal dongle in the middly which moves to release excess pressure.

Secondly even if it did not come out the the closing lugs bend under excessive pressure to allow the seal to leak and release the pressure. The bottom usually bends outwards a little too to create a domed effect.

Tony

 

[kevplumb]

My wife still believes that if a pan bubbles more then the water is hotter than boiling. Have tried to explain the science but she just does not undertand (or want to know??)

I would like to know - please could you explain the science to me?

water boils at 100c at atmospheric pressure after that it is a gas (steam) so how can the water get any hotter in an open pan

 

[Corgigrouch]

My wife still believes that if a pan bubbles more then the water is hotter than boiling. Have tried to explain the science but she just does not undertand (or want to know??)

I would like to know - please could you explain the science to me?

water boils at 100c at atmospheric pressure after that it is a gas (steam) so how can the water get any hotter in an open pan

Woman Logic..

Is the container completely filled with water or is there a small air bubble in there too?

Is the container infinitely strong or just strong in the OPs opinion? If the latter could we have some specifications for the container please because if the container is infinitely strong, then the water can never boil which makes a mockery of his original question..

 

[davebgas]

If the cylinder was connected to say taps and the water was underpressure and its temp got higher than 100degrees it would remain as a liquid until...... a hot draw off was opened and the stored water higher than atmospheric pressure would rapidly expand as we've said by 1600times, that extra space has to be taken up with something... hence boom....

If the cylinder was just a pure lump of one piece indestructable material and it was filled with no air gap and then heated then as the vessel is not open to atmosphere it would become a pressurised cylinder... and do...nothing.....as it cant because the container is 'indestructable'

If you are that interested in pressure vessels and the regulations there are many documents relating to high pressure storage... I have most on gas such as IGE/SR14 Part 1 on High pressure gas storage - above ground installations but its not really exciting

 

[bengasman]

My wife still believes that if a pan bubbles more then the water is hotter than boiling. Have tried to explain the science but she just does not undertand (or want to know??)

I would like to know - please could you explain the science to me?

You are joking right?

 

[iconic]

My wife still believes that if a pan bubbles more then the water is hotter than boiling. Have tried to explain the science but she just does not undertand (or want to know??)

I would like to know - please could you explain the science to me?

You are joking right?

No. I really would like to see IJWS15's explanation of why the water temperature does, or doesn't, stay under its boiling temperature.

 

[bengasman]

By definition, the boiling point is the maximum temperature of a liquid at a given pressure; normally that would be the atmospheric pressure. Adding more energy i.e. heat in this case, will result in more liquid evaporating, not an increase in temperature.

 

[iconic]

I like to see IJWS15's explanation of why the water temperature does, or doesn't, stay under its boiling temperature.

 

[Goldspoon]

My wife says food cooks faster when the lid is on... ?

I cannot understand the argument.

 

[bengasman]

I like to see IJWS15's explanation of why the water temperature does, or doesn't, stay under its boiling temperature.

Cant find that bit.

 

[bengasman]

My wife says food cooks faster when the lid is on... ?

I cannot understand the argument.

This is possible if you have for example a pot 150 mm high and only 10 - 20 mm of boiling water. If the steam is trapped, it will heat the veg that is not under water, like a pot full of kale.

 

[Corgigrouch]

My wife says food cooks faster when the lid is on... ?

I cannot understand the argument.

Only reason that I can think for her statement is that if the water didn't fully cover the food, then with the lid of the hot steam/ water vapour would leave the pan at a greater rate than with the lid on, thus the lid would raise the temperature in the air space above to close to 100c. As has been said before, increasing the pressure will increase the boiling point of water and this is the principal on which a pressure cooker works..... Conversely in reduced pressure, water can boil at temperatures well below the usual 100c application of a decent vacuum can result in water boiling at room temperature

 

[Nige F]

Well Thank Y`all ... Now when I put my old Lonnie Donegan record on .. "The Wreck of old 97 " I`ll know sure as heck that Steve the driver was scalded to death by the steam ..an` Glory be, I`ll know the physics of it

 

[Goldberg]

My wife says food cooks faster when the lid is on.

She's correct.

I cannot understand the argument.

A saucepan lid acts in the same way as a pressure cooker weight, by increasing the ambient air pressure inside the saucepan when the water reaches its boiling point. This raises the vapour pressure of the hot water, and so raises its boiling point, therefore the temperature at which the food is being cooked is higher.

FYI, you can also increase the cooking temperature by increasing the depth of the water in the pan.

Do you ever boil a kettle with the lid off? If not, why not?

If so, does the tea taste as good as when you put the lid on?

 

[kevplumb]

FYI, you can also increase the cooking temperature by increasing the depth of the water in the pan.

what a load of balls