SAFETY - boiling water in a microwave

Discussion in 'Health & Fitness' started by Michael 345, Mar 27, 2021.

  1. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    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 heatany liquid for more thantwo minutes per cup. After heating, let the cup stand in the microwave forthirty secondsbefore moving it or adding anything into it.

    Here is what a local high school 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 andwill particularly occurif 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 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.

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    Last edited: Mar 27, 2021
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  3. James R Just this guy, you know? Staff Member

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    Is there a question?
     
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  5. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

    Messages:
    12,314
    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 heatany liquid for more thantwo minutes per cup. After heating, let the cup stand in the microwave forthirty secondsbefore moving it or adding anything into it.

    Here is what a local high school 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 andwill particularly occurif 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 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.

    When I first started using microwave for cups of coffee I would boil up a cupful of plain water. First never injuries. Few messes

    They happened when I put the spoon of coffee in the hot water causing it to bubble up over the top of cup

    Anyone done the same sort of thing?

    Any other tips about operating microwave?

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  7. RainbowSingularity Valued Senior Member

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    don't use cracked plates cups or bowls or glasses or mugs
    they can explode from thermal warping when you open the door and take them out
    or sometimes when inside heating

    cracked or chipped, don't use it in the microwave
    dropped and it might be cracked
    don't use it

    anything that is sealed creating its own air bubble should not be microwaved because it will explode .

    don't put any metal in the microwave

    common issue
    thick soups and thick liquids

    heated too quickly & not stirred, they create heat pockets which then boil & bubble up
    they burn the edges and don't heat right through while creating a boiling liquid explosion risk to children\happens quite a lot to 1st time microwave users heating soups
     
    Last edited: Mar 27, 2021
  8. foghorn Valued Senior Member

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    1,006
    This may be obvious to some.
    I was visiting my mother when the microwave starting ''zapping'', it was the ''gold gilt'' pattern on the plate she had placed the mince pies on to warm up.
    But, she did know to remove the foil case from each pie before placing them in the microwave.
     
    Last edited: Mar 27, 2021
  9. DaveC426913 Valued Senior Member

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    16,689
    Happened to me just a few weeks ago, with a deli sandwich wrapped in (foil-lined) paper.

    I was facing away from the microwave, but the kitchen lit up like lightning. OMG, can foil-lined paper ever burn!
     
  10. exchemist Valued Senior Member

    Messages:
    11,199
    This is about superheating of a liquid, when there are no nuclei to trigger the formation of bubbles which allow it to boil.

    We used to add "anti-bumping" granules to liquids that we were distilling or evaporating in chemistry, to prevent superheating and then sudden, violent boiling - "bumping" - which could overflow the vessel or break apart the fittings. Some readers may also remember this from their school days. (In the 6th form I once caused a fire on the lab bench, as a result of failing to include anti-bumping granules

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    )

    Now for the physics, or at least my understanding of it:-

    The excess pressure inside a spherical bubble, due to the surface tension of the inside surface is 2T/r (r being the radius of the bubble and T the surface tension of the liquid). So the smaller the bubble, the greater the pressure needed to inflate it. While this is a macroscopic scale formula, that won't strictly apply down to the scale of individual molecules, the picture it gives that a huge excess pressure is need to blow up a bubble from zero, is directionally correct.

    Nuclei of some sort, such as a porous surface with minute air pockets or sharp edges, or a mechanical disturbance, such as moving the vessel containing the liquid, are needed to break a few molecules apart within the liquid to start the formation of the bubble. Once a bubble forms, it grows exponentially, since the excess pressure required to sustain it falls as the bubble expands.

    So basically you have an unstable situation, if there are no nuclei to "seed" bubble formation. This can be pseudo-explosive, so potentially nasty.

    The solution is to use a slight "dirty" container, e.g one with traces of scale from previous boiling.
     
    Last edited: Mar 28, 2021
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  11. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Have a new way make coffee now
    No need to boil a jug full (3 or 4 hundred ml for a 100ml coffee)
    That was the reason to use microwave (only heat the 100 needed)

    New way also safer than jug and microwave

    One of those capsule machines - without the capsule

    Put coffee in cup, place under spout, 50 ml hot water per press

    3 presses and a allowance for 50 ml of milk fills my cup, $2 Kmart

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  12. RainbowSingularity Valued Senior Member

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    7,105
    note, it may be quicker but it may use more electricity to keep the heater on
    efficiency of a new kettle may be less electricity for a single boil
     
  13. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Nope

    Switched off between cups

    Even if left on it automatically goes into low power mode

    Takes about a minute to warm up and pumps out hot 50ml about 20secs

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  14. RainbowSingularity Valued Senior Member

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    thats impressive

    i wonder if a gas fired instant water heater can do the same while using natural gas
    in countrys like india china & usa where they use coal fired electricity & heating it may be significantly less pollution and less CO2
    making cheap ones wont pass grade in usa
    but may be the only model that can make money in china & india

    being able to provide a few million to build the high tech factory would be expensive and you would need some regulators on the quiet in your pocket to prevent the idea from being stolen

    biggest markets india & china for tea drinking
    its a MASSIVE expense to income level
    when they are going to use the gas burner or coal fire or wood fire and keep that going.
    it would be a very expensive luxury item for them

    most investors want massive returns in exchange for betting millions on a new factory build

    being able to build in a country with no regulations on product standards would be needed but that would make sales to 1st countrys almost impossible
    and its 1st world investors who probably already own coffee machine tech and would spend millions fighting the idea in any way they could
    dirty tricks would be 24/7
     
    Last edited: Mar 28, 2021
  15. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Didn't instant gas Hot Water Shower units have a pilot light?

    Turn on the water, water pressure drops, gass turns on, almost instant hot shower water

    Pretty dangerous and haven't seen those in years

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  16. RainbowSingularity Valued Senior Member

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    7,105
    spark ignition battery or non battery
    you can have manual non electrical click spark

    mostly having 2 different controls is completely outside usa consumers ability to think clearly
    so it would not pass certification
    existing accidents with gas heaters would be used to attack the market to protect existing coffee machine makers and electric jug makers whom are large companys
    dirty tricks 24/7

    if you built the factory in India or china you might manage it
    but that takes lots of money and good connections

    probably around 3 million lump sum with 6 month lease and govt jobs system
    you might end up with a small scale high production for close to 8 million on a cheap factory build

    8 million is a lot to speculate on assuming you can grease the right official requirements for approval and land lease and labor law requirements
    etc etc
    customers would be almost exclusively Indian and Chinese
    and probably cater to lower income household birthday and Christmas presents as luxury items
    probably make some sales to new job start young adults also
    assuming they dont have a coffee machine
    they may want a tea machine
    local jug manufacturers would be against it.
    so locating and accessing the technology for the igniter and the bottle of gas and piping might face more 24/7 dirty tricks

    if you dont have the money and connections to combat the 24/7 dirty tricks you would lose your money
    additionally those who advertise to accept and partner with inventors steal their ideas and then make them, themselves
    THOSE type of people run the show mostly
    no morals no honor, those who do have honor and morals wont be interested in the risks ad smaller potential profit margin or the political wrangling required when they already have safe bets running ok
    thats the real world
    i have no shortage of creative new ideas
    just no honest honorable moral people to partner with
     
    Last edited: Mar 28, 2021
  17. Beer w/Straw Transcendental Ignorance! Valued Senior Member

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  18. exchemist Valued Senior Member

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    Nice demo.
     
  19. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Thank you

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  20. exchemist Valued Senior Member

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    In fact, thinking about this further, there may be another contributory factor. Conventional boiling of water involves transferring heat from a very hot surface (base of pan, electric heating element) into the cooler bulk of the liquid. So as boiling point is approached, a layer of water next to the hot surface may become superheated. But the moment this superheated layer finally boils, it is safely "quenched" by the bulk liquid, which is not yet at boiling point. So there is not much danger of the bulk liquid becoming superheated. Whereas a microwave oven heats the water evenly throughout - or nearly so - with no part liable to form bubbles first and thereby "defuse" the potential for superheating of the rest.

    So it all reaches boiling point at once and so, if it superheats, it ALL superheats!

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  21. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Can any mod please rename this thread SAFETY IN GENERAL
    Thank you



    This short video is about the importance of wearing Safety Vest

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  22. wegs Matter and Pixie Dust Valued Senior Member

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    I like watching water boil on the stove lol Not sure if I’ve ever heated anything in the microwave, to the point of boiling/scorching/burning. Hmm.
     
  23. Seattle Valued Senior Member

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