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Is it dangerous to compress carbon dioxide under high pressure?

  1. Jun 14, 2012 #1
    Is it dangerous to compress carbon dioxide under high pressure?
     
  2. jcsd
  3. Jun 14, 2012 #2

    berkeman

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    Staff: Mentor

    What is the context of your question? You already asked a similar question a few days ago in this thread about carbon monoxide:

    https://www.physicsforums.com/showthread.php?t=612769

    And what do you mean by dangerous? If the pressure vessel is not strong enough, pretty much any gas under pressure can be dangerous.
     
  4. Jun 14, 2012 #3
    yeah sorry about the double post. I felt i was not clear the first time. What i wanted to know is if carbon dioxide is pressurized will it cause a issue? Does it make it more fragile.. or something like that
     
  5. Jun 14, 2012 #4
    Anything under compression stores energy and can be dangerous. If a pressure vessel ruptures it can be lethal. Gasses are typically more dangerous as they are more easily compressed. In construction when at all possible pipe systems are tested for leaks using a liquid instead of a gas, because it is less dangerous due needing less stored energy.

    Carbon Dioxide is inert, so if compressed properly, it should be safe. It also becomes a liquid at around 800-900psi room temperature, so in most cases it won't be compressed beyond that. (do a search for a CO2 phase chart)

    You can buy liquid CO2 in a tank at a welding supply store, beverage companies (for beer and soda), or even at paint-ball suppliers. As the outside temperature increase these tanks can build pressure fast when full (and possibly rupture); therefore, they are not filled all the way. This allows for a gas pocket to be compressed if temperature rises (as the tank is used the liquid boils off and the gas/liquid ratio changes, the pressure in the tank stays relatively constant, so these tanks are checked for fullness by weight, not pressure.) Also all tanks over 5# have a safety pressure release valve, in case the pressure builds too high.
     
  6. Jun 14, 2012 #5
    ...also to clarify i should probably say that liquids are typically safer only for certain situations as stated above like in pipe testing. This allows you to use something which is roughly at room temperature, and pressure.

    Obviously CO2 in a liquid state is more dangerous when compressed to 800-900psi than a gaseous CO2 at lower pressures. CO2 also sublimates at atmospheric pressure (dry ice does not melt, it turns directly into gas.)
     
  7. Jun 14, 2012 #6
    CO2 used to be used in fire extinguishers to smother fires. It is stored in the extinguishers under pressure at about 70 atm (7 megapascals). When released, it comes out as dry ice (solid CO2) and rapidly cools and smothers flammable liquid, electrical, and metal (e.g., magnesium) fires.

    CO2 gas, which is heavier than air, can collect in low areas or depressions and smother unsuspecting animals. High pressure CO2 from volcanic fissures under Lake Nyos in Camaroon collected under several hundred feet of water. In 1986, The lake "exploded" and released over 1 million tonnes of CO2, and asphyxiated over 1800 people. See http://en.wikipedia.org/wiki/Lake_Nyos

    Compressed CO2 is used for enhancing oil recovery from old wells. See http://www.netl.doe.gov/technologies/oil-gas/publications/EP/small_CO2_eor_primer.pdf "Green Coal" supporters are proposing compressing CO2 (carbon capture and storage) and storing it in old oil wells and geological formations. The CO2 would be compressed and stored as a liquid. See http://en.wikipedia.org/wiki/Carbon_capture_and_storage

    Is it safe to store supercritical CO2 (70 atm and 30 degrees C) underground in deep geological formations? Is it safe to store in a house? [I have had a 5-pound CO2 fire extinguisher in my house for about 50 years].
     
  8. Jun 14, 2012 #7
    Most of the white stuff seen is condensation of the water vapour in the air.
     
  9. Jun 14, 2012 #8
    for basically your reply applies for any gas right? I mean is there any difference between compressing air and carbon dioxide, except you said carbon dioxide when compressed is inert. I'm assuming air is also inert because it is often compressed. But some gases are not inert right, what happens then? sorry im very new to physics i'm trying to brainstorm some ideas for a project
     
    Last edited by a moderator: Jun 14, 2012
  10. Jun 14, 2012 #9
    No. Carbon Dioxide may be safely compressed. It will not explode. It will not deflagrate.
     
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