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Thread: Pistol stuck to MRI machine - GIF

  1. #11
    Supporting Member NeiljohnUK's Avatar
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    Quote Originally Posted by 12L14 View Post
    „Party balloons” are filled with a „leftover” helium from MRI - not „fresh” one.
    Still a waste, we have a Helium recovery and repurification plant that runs 24/365 to capture and recycle Helium used, as in an MRI scanner, for superconducting magnet cooling, one of my jobs is topping up and and recovery of Helium in some of those units. Many of the cylinder suppliers here use the same grade of Helium as they sell for other industrial uses for 'balloon gas', recovered or "left-over" Helium gets fed into their bulk supply for all uses once cleaned up.

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  2. #12
    Supporting Member hemmjo's Avatar
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    Well this is interesting reading . I was not aware of these facts.

    Specifically the last section on that page; (bold added my me)

    How Does An MRI Machine Use Helium
    An MRI machine contains coils, a magnet and wires that conduct current. The machine uses a great deal of energy because of its large magnetic field. In order for it to use that much energy, it must be super conductive. For this to occur, wires inside the machine need to be reduced to a temperature of near zero degrees. The machine requires a substance in order for it to maintain a cold temperature, and that substance is liquid helium. The wires continuously are doused with liquid helium. The fluid has a temperature of -269.1 degrees Celsius, which is the equivalent of -452.11 Fahrenheit. The average MRI machine utilizes 1,700 liters of helium. A standard 18″ balloon requires about .1 oz of helium, and the machine uses about 56,100 oz to give you a mental picture of how much helium that is. The amount of helium in the scanner must be topped off on a regular basis, which increases the amount of helium used by the machine even further.

    Unfortunately, the amount of helium on earth is diminishing due to its heavy usage, and it floating away. There isnít much of it on earth because itís not weighed down to the atmosphere. Itís slowly, but continuously, floating off into space. The noble gas is unable to be synthesized and is usually made through natural radioactive decay. Once the helium is gone, itís gone forever because itís a nonrenewable resource. The medical field requires a large quantity of helium to assist patients with diagnosing and monitoring their condition, which is by far a vital and valued use.

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    NeiljohnUK (Sep 12, 2022), Rangi (Sep 12, 2022)

  4. #13
    Supporting Member mklotz's Avatar
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    Advancing technology can eventually decrease the use of liquid helium to achieve superconductivity. There are already room temperature superconductors, albeit at extreme pressures too high to be practical...

    https://www.unlv.edu/news/release/lo...om-temperature

    There are many superconductors...

    https://en.wikipedia.org/wiki/List_of_superconductors

    The engineering tradeoffs include more than the temperature needed to go super. If a superconductor is exposed to too high a magnetic field it will crash. This effect limits the amount of current a superconducting wire in an electromagnet can carry.

    I'm reasonably confident that we'll be able to build an MRI in the next decade or two that can operate on liquid nitrogen temperatures.
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    Regards, Marv

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  5. #14
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    Quote Originally Posted by hemmjo View Post
    MRI machines are part of the reason that Helium is in short supply.
    Yes but also mostly no. The US decided to decommission the national helium reserve in the mid 90s, so they basically flooded the market with cheap helium. So for 20 years the price of helium was artificially depressed, which skewed the economics of projects that required helium. Now that the US is no longer dumping helium, the price has equalized. While it's true that it's mostly non-renewable, the fact is that there's an abundance but it's just not worth recovering. Nearly every natural gas project on the planet just vents the stuff to the atmosphere in truly monumental scales.

    Also you're totally right about it escaping the atmosphere, and it's super interesting. Helium is monoatomic and very light. To have the similar kinetic energy as other atmospheric gases (i.e. temperature) the atoms have to go super fast. How fast you say? Faster than the escape velocity of the earth. That's why there's no helium in the atmosphere. It shoots off into space and never comes back because it's actually going fast enough to escape the gravity well of the Earth.



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