5 ms·

A party balloon full of helium is a minuscule amount?

sandworm101 6y ago
Note this is liquid helium in one operational MRI machine: "Let’s say you have an MRI scanner with the OR76 magnet with the full capacity of 1800 litres of helium. Your system consumes approximately 4% of its helium capacity per month, that sums up to 48% per year (4%12 = 48%). That means that 864 litres are consumed per year (1800 litres 48% = 864 litres)." https://lbnmedical.com/liquid-helium-in-mri-machine/ https://lbnmedical.com/liquid-helium-in-mri-machine/ That is liquid, so for the gas we can multiply 864 by about 1000. So this MRI machine is using 86,000 liters of helium gas per year. That is what, 40,000 party balloons? Say each machine does 1000 scans per year, that is a good-sized cluster of party balloons for every scan. So yes, a single party balloon pales in comparison to the amount of helium being used for MRI scans. (There are near-zero helium MRI machines, but there are also plenty of older machines in use out there.)
- m4rtink 6y ago
  Many modern liquid rocket engine powered space launchers also use quite a lot of helium for tank pressurisation in flight. Helium being inert with very low melting point is ideal for this use case, especially with cryogenic propelants. With the most modern generation of reusable space launchers such as SpaceX starship an alternative solution is being worked on, possible thanks to both fuel (methane) and oxidizer (oxygen) they use being cryogenic. Instead of pressurizing with helium they heat up a bit of the cryogenic liquids using the rocket engine heat, let it expand into gas and use it to pressurize the tanks, no helium required! One of the reasons is that for fully reusable space launchers the main cost is the propelant and helium in the amounts needed would be a big part of that!
  - Gravityloss 6y ago
    In some cases the helium cost is comparable to that of the propellants! Both are negligible compared to the total cost of space launch currently, but once reusability and operations become more streamlined, they start mattering more.
- gibspaulding 6y ago
  > "Let’s say you have an MRI scanner with the OR76 magnet with the full capacity of 1800 litres of helium. Your system consumes approximately 4% of its helium capacity per month, that sums up to 48% per year (4%12 = 48%). That means that 864 litres are consumed per year (1800 litres 48% = 864 litres)." I know this is napkin math so it doesn't really matter, but a 4% loss times 12 months would be 1-(.96^12) = 39%. Unless of course they're topping up the helium every month.
  - sandworm101 6y ago
    I'm not sure that the percentage matters in cooling. This stuff is cooling working parts (magnets). Boiling is therefore related to the amount of heat needing to be absorbed rather than the amount of helium in the tank. A half-empty machine would probably need to boil off just as much helium per time/use/work cycle as a full one. The other error I now realize is that these HDDs probably have much less helium than any party balloon. They appear to be below atmospheric pressure and are so small that they are probably less than a tenth of a liter each. So one MRI scan is probably the equivalent of hundreds of these HDDs.
    - sbierwagen 6y ago
      Superconducting magnets don't produce heat. (They are superconducting) All the heat comes from the resistive feeder cables and the walls of the cryostat.
  - mlyle 6y ago
    Loses a percentage of its capacity, not a percentage of the amount of helium it has.
  - deleted 6y ago
    [deleted]
- temp0826 6y ago
  Thanks, this thread just made “number of party balloons” my new favorite unit of measure
- moonbug 6y ago
  balloon gas is typically about 90% helium and is generally a recycling of helium expended in industrial applications.
- Dylan16807 6y ago
  > (There are near-zero helium MRI machines, but there are also plenty of older machines in use out there.) For the purpose of worrying about future supply, we probably want to compare to those. A balloon is a tiny waste compared to an MRI that vents helium willy-nilly, but it's a much larger waste compared to an MRI that gives half a care.

Note this is liquid helium in one operational MRI machine: "Let’s say you have an MRI scanner with the OR76 magnet with the full capacity of 1800 litres of helium. Your system consumes approximately 4% of its helium capacity per month, that sums up to 48% per year (4%12 = 48%). That means that 864 litres are consumed per year (1800 litres 48% = 864 litres)." https://lbnmedical.com/liquid-helium-in-mri-machine/ https://lbnmedical.com/liquid-helium-in-mri-machine/ That is liquid, so for the gas we can multiply 864 by about 1000. So this MRI machine is using 86,000 liters of helium gas per year. That is what, 40,000 party balloons? Say each machine does 1000 scans per year, that is a good-sized cluster of party balloons for every scan. So yes, a single party balloon pales in comparison to the amount of helium being used for MRI scans. (There are near-zero helium MRI machines, but there are also plenty of older machines in use out there.)

m4rtink 6y ago
Many modern liquid rocket engine powered space launchers also use quite a lot of helium for tank pressurisation in flight. Helium being inert with very low melting point is ideal for this use case, especially with cryogenic propelants. With the most modern generation of reusable space launchers such as SpaceX starship an alternative solution is being worked on, possible thanks to both fuel (methane) and oxidizer (oxygen) they use being cryogenic. Instead of pressurizing with helium they heat up a bit of the cryogenic liquids using the rocket engine heat, let it expand into gas and use it to pressurize the tanks, no helium required! One of the reasons is that for fully reusable space launchers the main cost is the propelant and helium in the amounts needed would be a big part of that!
- Gravityloss 6y ago
  In some cases the helium cost is comparable to that of the propellants! Both are negligible compared to the total cost of space launch currently, but once reusability and operations become more streamlined, they start mattering more.
gibspaulding 6y ago
> "Let’s say you have an MRI scanner with the OR76 magnet with the full capacity of 1800 litres of helium. Your system consumes approximately 4% of its helium capacity per month, that sums up to 48% per year (4%12 = 48%). That means that 864 litres are consumed per year (1800 litres 48% = 864 litres)." I know this is napkin math so it doesn't really matter, but a 4% loss times 12 months would be 1-(.96^12) = 39%. Unless of course they're topping up the helium every month.
- sandworm101 6y ago
  I'm not sure that the percentage matters in cooling. This stuff is cooling working parts (magnets). Boiling is therefore related to the amount of heat needing to be absorbed rather than the amount of helium in the tank. A half-empty machine would probably need to boil off just as much helium per time/use/work cycle as a full one. The other error I now realize is that these HDDs probably have much less helium than any party balloon. They appear to be below atmospheric pressure and are so small that they are probably less than a tenth of a liter each. So one MRI scan is probably the equivalent of hundreds of these HDDs.
  - sbierwagen 6y ago
    Superconducting magnets don't produce heat. (They are superconducting) All the heat comes from the resistive feeder cables and the walls of the cryostat.
- mlyle 6y ago
  Loses a percentage of its capacity, not a percentage of the amount of helium it has.
- deleted 6y ago
  [deleted]
temp0826 6y ago
Thanks, this thread just made “number of party balloons” my new favorite unit of measure
moonbug 6y ago
balloon gas is typically about 90% helium and is generally a recycling of helium expended in industrial applications.
Dylan16807 6y ago
> (There are near-zero helium MRI machines, but there are also plenty of older machines in use out there.) For the purpose of worrying about future supply, we probably want to compare to those. A balloon is a tiny waste compared to an MRI that vents helium willy-nilly, but it's a much larger waste compared to an MRI that gives half a care.