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Thread: Ar % of gas mix

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    New Member Peter Bomberg is an unknown quantity at this point Peter Bomberg's Avatar
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    Ar % of gas mix

    I am thinking of manufacturing my own 02 mix however the device I am looking at using will result in a Ar ratio of 4.2% rather than 0.93% that is normal, so the question is does anyone have experience with this high ratio and or can anyone point me at a method to reduce the Ar ratio in a gas mix, I know the issue with Ar is the 02 binding properties but if it's in the breathing mix does that still apply or will it already have bound the 02?

    Anyways help appreciated.

    Peter

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    Re: Ar % of gas mix

    Quote Originally Posted by Peter Bomberg  View Original Post
    I am thinking of manufacturing my own 02 mix however the device I am looking at using will result in a Ar ratio of 4.2% rather than 0.93% that is normal, so the question is does anyone have experience with this high ratio and or can anyone point me at a method to reduce the Ar ratio in a gas mix, I know the issue with Ar is the 02 binding properties but if it's in the breathing mix does that still apply or will it already have bound the 02?

    Anyways help appreciated.

    Peter
    I thought the primary problem with Argon in a breathing mix is that it is very narcotic, far more so than nitrogen. I'm not aware of O2 binding properties but then again, I'm not a gas blender

    David

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    Re: Ar % of gas mix

    Quote Originally Posted by Peter Bomberg  View Original Post
    ... I know the issue with Ar is the 02 binding properties but if it's in the breathing mix does that still apply or will it already have bound the 02?
    Argon is inert (except and extremely high energies that alow ionization but thats not important right now).

    It reacts with nothing, not even itself. It is extremely narcotic under preasure, much more than nitrogen.

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    Re: Ar % of gas mix

    Quote Originally Posted by Peter Bomberg  View Original Post
    ... I know the issue with Ar is the 02 binding properties but if it's in the breathing mix does that still apply or will it already have bound the 02?

    Anyways help appreciated.

    Peter
    You may have some false info. Argon is an inert noble gas. It does not bind with O2. Have you been reading the fictionary?

    The problem with argon in CC use is the accumulation in the loop. It will effect the narcosis.

    Follow-up question: How does it effect decompression?

    -Pasi

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    Re: Ar % of gas mix

    Quote Originally Posted by plazma  View Original Post
    You may have some false info. Argon is an inert noble gas. It does not bind with O2. Have you been reading the fictionary?
    Perhaps he means that argon (when used when MIG welding or similar) forms a screen that prevents oxygen reacting with the weld bead. It doesn't bind oxygen per se, but just forms a shield of inert gas.

    Follow-up question: How does it effect decompression?

    -Pasi
    Heh - who knows I doubt anybody seriously intends to make argox trimix tables

    David

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    Re: Ar % of gas mix

    Quote Originally Posted by Peter Bomberg  View Original Post
    I am thinking of manufacturing my own 02 mix however the device I am looking at using will result in a Ar ratio of 4.2% rather than 0.93% that is normal, so the question is does anyone have experience with this high ratio and or can anyone point me at a method to reduce the Ar ratio in a gas mix, I know the issue with Ar is the 02 binding properties but if it's in the breathing mix does that still apply or will it already have bound the 02?

    Anyways help appreciated.

    Peter
    hey peter !!! you have to get rid off argon in total... argon is a bad gas and only usable as a suit gas....
    when used in a suit it will isolate very vell from cold but if inhaled even in small quantities it is really dangerous.....i really reccomend you to looka at gas physics..... check out matti@antti.la.... page is called exotic diving gases.... it is very informative what you can do and use with different gases...
    with best regards mogge

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    Re: Ar % of gas mix

    Quote Originally Posted by mogge_mek  View Original Post
    hey peter !!! you have to get rid off argon in total...
    Utter nonsense. argox is a known yet little used decompression gas. Argonox 50/50 could be used from 21m and up if you're prepared to roughly have an equal narcotic effect as air on 60m. (Better use it shallower) Do a search on Argonox on wikipedia and while you're at it check the external links. IIRC (can't find a source for it) one of the drawbacks of argon is that an argon bend is hard to fix which along with it being largely unknown quantity prevents it from being used widely. Price should be a factor for rebreather divers especially since only used shallow.
    Actually I'm surprised that it isn't used on extremely deep dives during deco in an attempt to keep both pulmonary oxygen toxicity and cns under control....

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    Re: Ar % of gas mix

    Quote Originally Posted by Dutchy  View Original Post
    Actually I'm surprised that it isn't used on extremely deep dives during deco in an attempt to keep both pulmonary oxygen toxicity and cns under control....
    Looks like you answer your own question.

    Quote Originally Posted by Dutchy  View Original Post
    Argonox 50/50 could be used from 21m and up if you're prepared to roughly have an equal narcotic effect as air on 60m.

    IIRC (can't find a source for it) one of the drawbacks of argon is that an argon bend is hard to fix which along with it being largely unknown quantity prevents it from being used widely.
    But in the context of the OP's question...

    Lots of Argon in your loop is not a desirable thing. Its highly narcotic and will build up if it comes in with the O2 since it won't be metablized. How bad? How much is ok? Those questions need someone with more knowledge than me to answer.

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    Re: Ar % of gas mix

    Dry air is 20.947% oxygen and 0.934% argon. If you sieve out the nitrogen with a membrane, the ratios of the oxygen and argon remain the same, so if you make nitrox 90% with your membrane, you will have 4.0% argon in there.

    Argon is 2.33x as narcotic as nitrogen.

    The trouble with this on closed circuit is that because the argon is inert, it builds up in the loop. Every time the solenoid adds the nitrox 90 you made to your loop it increases the concentration of argon in the loop. If the dive is a long one it could be a problem:

    If you did a 2 hour dive with that nitrox 90 and consumed 1.4 litres/min of oxygen, you'd add 7.5 litres of argon to the loop over the course of the dive. The loop is, what, 8 litres? Now that's narcosis!

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    Re: Ar % of gas mix

    Quote Originally Posted by cramerdn  View Original Post
    Looks like you answer your own question.
    It really is a question. Ideally you have none at depth then use it shallow (to avoid ongassing as much as possible) for the aforementioned reasons.

    Quote Originally Posted by cramerdn  View Original Post
    But in the context of the OP's question...
    Lots of Argon in your loop is not a desirable thing. Its highly narcotic and will build up if it comes in with the O2 since it won't be metablized..
    I responded to the uneducated earlier response that said none. The way you phrase it I absolutely agree.

    Quote Originally Posted by cramerdn  View Original Post
    How bad? How much is ok? Those questions need someone with more knowledge than me to answer.
    No you don't! The good thing is that you CAN calculate yourself and deal with it accordingly!

    First calibrate your O2 measuring device. Then measure O2 content in your alleged O2. Assume everything not O2 is argon (to be on the safe side with respect to argon).

    let's assume that is 10% for now. You know what you metabolize. Let's assume 2l/minute. It means you'll be injecting .2l/min of pure Argon.

    What can you tolerate (or do you want to tolerate?) Assume argon effect and N2 add up. (once more on the carefull side)
    With argon being some 2.5 times as narcotic you'll need to add narcotic depth for argon. 1 Bar of Ar corresponds to 0.8*2.5*10 = 20m of narcotic depth.

    Assume you think pPN2 of 3.2 Bar is acceptable. (roughly 30m on air) add to that the 20m and you'll have 50m of narcotic depth

    Now how fast does that .2l/min build up to 1 Bar? That is the thing I can't tell you. You need to know your total loop volume for that. Assume it to be 10l (You need to know for your specific purpose, if you want to be on the safe side only measure the Rebreather volume with minimum loop, not yourself)). In that case it holds 50 free liters @ 5 Bar. You need 10l to get 1 Bar which corresponds to 50 minutes. (assuming you never accidentally loose gas/argon ;) ) Of course on a 100m dive you'll need to flush more often than that.

    Argon is bad but let's be realistic here... You see that even with all factors chosen badly the outcome is still not too bad. Please compensate for factors you alter like having He in the mix to lower END or better O2 content and you see it becomes on non-issue. (unless I made calculation errors ...)
    Last edited by Dutchy; 8th December 2008 at 21:57.

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