How would steam pressure move a lid?

Discussion in 'Physics & Math' started by Bob-a-builder, Jun 14, 2019.

  1. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Yes, you did CLAIM that the pressure would get more powerful. And it was pointed out that it wouldn't by several people.
    What you did NOT say, or imply was that "the water will boil so fast and fervently".
    And yet, again, all you present are unsupported claims and denial of what everyone else here is telling you.
     
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  3. DaveC426913 Valued Senior Member

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    Bob: If you're looking for a flame war, keep at it. If you're looking for a rational discussion, maybe start off that way.

    Fewer unfounded assertions, more asking of questions will get you the discussion you want.

    People here know what they're talking about, and you're not nearly as knowledgeable as you think you are.

    You state so many misleading half-truths and unfounded conjectures in one breath there's simply no practical way to correct you without clearing the whole table and starting from scratch.

    So, start at the beginning. Make one statement that you're sure of, and we'll weigh in to correct it.
     
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  5. Bob-a-builder Registered Senior Member

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    Okay.. Ill bite.
    I said "However.. Your next trick is to make a claim and put words in my mouth. It's called Stawman.. so lets have it then."

    You now say,
    Can you actually quote where this has been done? Or are you simply making stuff up again?

    I COULD QUOTE THIS A DOZEN TIMES IN PAST WEEK. FROM RANDY CLAIMING I SUGGESTED ALIENS TO A RAINBOW GUY SUGGESTING 70 TON BOXES WERE MOVED DAILY (with logs for some reason.. he sounded like he was on crack)


    But MOST RECENTLY IN PAST 3 COMMENTS

    I had said the water will boil so fast and fervently (look it up dave) that tiny lift it used to let steam escape won't be enough.


    Dave C replied "This is not what you claimed earlier."

    ANYONE can look at my unedited first post (cannot edit since yesterday) and see I said

    The pressure gets extremely more powerful for this example.

    So yes.. Strawman.

    THAT IS WHAT A STRAWMAN ARGUMENT IS.

    If you do not have the intelligence to debate a topic, you just pretend the person is saying different things and argue against that.

    I'm thoroughly convinced you are both very dumb people.

    I guess nobody in a physics forum knows how boiling water works.
     
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  7. DaveC426913 Valued Senior Member

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    Except that this is the quote I was addressing (posts 9, 12, 15, 16):
     
  8. DaveC426913 Valued Senior Member

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    Are we going to start again, or are we just going to keep going round and round? Your call.
     
  9. Bob-a-builder Registered Senior Member

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    119
    double post deleted
     
  10. Bob-a-builder Registered Senior Member

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    Strawman AGAIN. Are you suggesting you are not aware of the parameters of the experiment now DAVE!

    The lid is free moving. It is not attached in any way. Increasing pressure will seek alternate routes of ventilation to lower pressure.
    ROMPER ROOM!

    This is the context. This has been stated time and again.

    IN THAT EXPERIMENT.

    "Steady building pressure would not find satisfaction with just one route to lower pressure."

    You say that is wrong.. but unless you go all STRAWMAN for third posting in a row.. You cannot attack that sentence.
     
  11. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    18,899
    And yet you only manage the once -
    Still wrong, as has been pointed out.
    You were told that the pressure does not, and cannot, "get more powerful" in a boiling pan.
    Since that IS the case your wording of "boiling so fast and fervently" was taken as a shift of goal posts.

    No, a misunderstanding based on your lack of clarity AND your lack of ability to accept facts.
    It's obvious that you don't, at least...
     
    Last edited: Jun 15, 2019
  12. Neddy Bate Valued Senior Member

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    1,838
    I have a pressure cooker that has a little weight on top which gets lifted up when the internal pressure is great enough. It lifts just enough to let some steam vent out. Once that starts to happen periodically, the pressure cooker maintains a constant pressure. There is a pressure gage on top which anyone can look at to confirm this. The pressure does not keep increasing endlessly, contrary to what the OP seems to be claiming.
     
  13. billvon Valued Senior Member

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    15,783
    Nope. Not true in theory - or in practice.
     
  14. sideshowbob Sorry, wrong number. Valued Senior Member

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    5,596
    In your scenario, with the lid held on only by gravity, the pressure can not grow in intensity.
     
  15. Bob-a-builder Registered Senior Member

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    119
    Thanks for at least giving a thoughtful answer.

    What if the lid itself was thin/light? I used a piece of sheet metal for example. I thought that was obvious. Since we are DISCUSSING the movement of a lid under pressure. I thought it fair to assume the lid was not 100 lbs for such an experiment. I suppose I should have drawn some diagrams.

    In earlier postings I described the experiment like a square meatloaf container being boiled with a light (lighter than a pressure cooker lid or stainless steel) rectangular sheet metal flat lid with roughly a 10% overlap. Nothing holding it down.

    I have suggested the lid would vibrate rapidly as all pot lids do riding on the escaping streams of steam. Making it bounce based on pressures and gravity and design.

    This is a child level physics experiment.

    When pressure is released from an object it only releases enough steam to overcome the gravity force seal of the flat lid. The pot still would contain pressure, just not enough to overcome that seal. The lid would settle back down again. That is NOT the end of the story. The water would continue to accept heat and convert water into ever increasing amounts of steam. This can be learned by watching any kettle. After some time. The water would be converting to steam gas at such a high rate that a little "burp" of venting would not satisfy the pressure requirements of the remaining steam. At this point the lid would start to vent more from high pressure to low pressure. This lid will then "float" on the pressure to degrees. It would likely bounce and flop and move as there is no tongue in groove (nothing keeping it on at all except gravity). It would just be releasing steam at the rate it requires in this "growing pressure state"

    (I'm pretty sure I said all that in my opening post, but had to dumb it down a bit for some here).

    I thought a science forum would have people that new simple stuff like mechanics of steam.
     
  16. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    18,899
    No.
    Because every time the pressure rises enough to lift the lid at all the pressure is reduced and the lid falls back.
    And yet you don't...
     
  17. RainbowSingularity Valued Senior Member

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    2,992
    not to mention then it loosing
    fuel(heating) energy
    water energy

    what happens to solid granite pots when you boil them on an open fire ?
    i am guessing they crack very quickly
    unles he is refering to them having the steam on the inside by
    infecting the bull with a parasite that then kills and and makes it rot inside the box increasing pressure
    however...
    there is probably only a certain amount of bio-physics availible to the relative need for oxygen to convert to vapour pressure as bacteria parasites or fungus wont be able to completely reduce the bull carcus to its maximum water content to then convert to steam....
    which might lift the lid, but probably only once for a nano second

    to achieve what ?

    is there any parasite
    fungus
    bacteria
    that can kill convert a bull body that has suffocated to death in a small box into 99% of its liquid water volume then turn that into steam ?

    im ready to get off this roundabout of nonsense unless you can post some links to crypto-bactarial(fungus/parasite) science that is peer reviewed

    most likely way the bulls got inside was they were put there to create interest for tourism and get world headlines.
    not very interesting if they were all empty.
    in the late 1800s through the boom era of the early 1900's things like mysticism and animal sacrifices was hot news headlines for well educated sophisticated folk to see a secret world they have never known.
    it was a massive industry.
     
    Last edited: Jun 16, 2019
  18. billvon Valued Senior Member

    Messages:
    15,783
    It might. Or it might lift just enough to vent the steam, and then remain with that opening. Depends on the dynamics of the lid (not a simple problem.)
    There's no real seal. There's a surface that steam is pressing against. When the steam pressure overcomes the weight of the cover then the cover will lift just enough to exhaust the steam.
    Not if the pressure remains there.
    At equilibrium, given a steady input of heat, a constant amount of steam will be generated.
    It does. Hopefully you learned something.
     
  19. Michael 345 New year. PRESENT is 69 years old Valued Senior Member

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    You shouldn't because that is WAY above your pay scale

    Better you sit with the toddlers

    Please Register or Log in to view the hidden image!

     
  20. RainbowSingularity Valued Senior Member

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    ?

    Please Register or Log in to view the hidden image!


    must admit russel looks very sexy if you dont mind the politics
    (great movie, quite violent though)
     
  21. DaveC426913 Valued Senior Member

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    12,232
    What's silly about this whole thread is: even if by some magical suspension of the laws of nature we all granted it to be true, it still doesn't lend credence to the thread that spawned it - the one about sarcophagus batteries.

    I could make up an idea I like that the sarcophagi were built to hold food for Egyptian winters, and the corners aren't busted off but chewed off by hungry locusts trying to get at the food. There's just as much evidence for my idea as Bob's - which is none. And it is just as plausible as Bob's - which is not.

    It causes me physical pain to read Bob's posts. Like browsing the Flat Earth Society website.

    :unsub:
     
  22. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    18,899
    This is like claiming that on filling a cup with water once it's first overflowed you can keep pouring more water into it (i.e. above the top of the cup) until suddenly the column of water that's not actually in the cup will then overflow.
    One more time: as soon as the internal pressure is high enough to lift the lid the lid will be lifted. It is not physically possible for that lid to fall back after the initial pressure release and then contain more pressure than it did the first time. The pressure required to lift the lid is a fixed value.
     
  23. exchemist Valued Senior Member

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    8,138
    Surely this thread is all a confusion between pressure and rate of flow, isn't it? As you and others have pointed out, the pressure will NOT rise any more if the rate of steam generation increases, but the rate of flow of steam will increase, creating a larger opening for it to escape through, by lifting the lid higher.
     
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