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Thread: Making air

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    Established TDF Member taz's Avatar
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    Making air

    .

    Is there any reason why we can't make air from from oxygen and nitrogen?

    Given an unlimited amount of 100% pure gas in both oxygen and nitrogen would it be as simple as putting the correct amounts of both into a cylinder?

    taz


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    Cheeky Monkey... Paul Evans's Avatar
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    Quote Originally Posted by taz View Post
    .

    Is there any reason why we can't make air from from oxygen and nitrogen?

    Given an unlimited amount of 100% pure gas in both oxygen and nitrogen would it be as simple as putting the correct amounts of both into a cylinder?

    taz


    .
    Cost?
    “Attitude is a choice. Happiness is a choice. Optimism is a choice. Kindness is a choice. Giving is a choice. Respect is a choice. Whatever choice you make makes you. Choose wisely.”
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    Quote Originally Posted by taz View Post
    .

    Is there any reason why we can't make air from from oxygen and nitrogen?
    Given an unlimited amount of 100% pure gas in both oxygen and nitrogen would it be as simple as putting the correct amounts of both into a cylinder?
    taz
    We do it already. Its called Synthetic Air

    Sometimes made up from from liquid oxygen LOX and Liquid Nitrogen, depending on the required pressure and purity.
    Used for span gas to calibrate gas detectors, medical air and in Atomic Absorption Spectroscopy.

    A similar idea used to be used offshore for mixing dive gas on the fly called a Mixmaker.
    But using bottled gas including helium, useful in the days when oil rigs were bolted to the sea bed and inspections
    would be from the splash zone (air range) down to the sea bed for example Fortes Bravo 411 ft on the sea bed and horizontal diagonal nodes needing
    inspecting every 33 foot down.

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    No problem doing it, can be a bodge it way to blend trimix if you don't have a compressor.

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    Established TDF Member taz's Avatar
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    Quote Originally Posted by Paul Evans View Post
    Cost?
    Hypothetically lets say you have an unlimited amount of gas (legally) and the equipment to do it

    Quote Originally Posted by iain/hsm View Post
    We do it already. Its called Synthetic Air

    Sometimes made up from from liquid oxygen LOX and Liquid Nitrogen, depending on the required pressure and purity.
    Used for span gas to calibrate gas detectors, medical air and in Atomic Absorption Spectroscopy.

    A similar idea used to be used offshore for mixing dive gas on the fly called a Mixmaker.
    But using bottled gas including helium, useful in the days when oil rigs were bolted to the sea bed and inspections
    would be from the splash zone (air range) down to the sea bed for example Fortes Bravo 411 ft on the sea bed and horizontal diagonal nodes needing
    inspecting every 33 foot down.
    Intresting.......... If we blend different gasses why not blend air? Is it just as simple as cost?

    Quote Originally Posted by WFO View Post
    No problem doing it, can be a bodge it way to blend trimix if you don't have a compressor.
    That's what I was thinking



    taz

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    Cheeky Monkey... Paul Evans's Avatar
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    So........

    Cost
    Time
    Space
    Safety

    Even with a cascade your going to lose gas.
    Without a booster or compressor you can never actually fill anything to 232. 300bar is out.
    Its much quicker to run a compressor.
    Its much safer to run a compressor.

    And thats just Air...................

    “Attitude is a choice. Happiness is a choice. Optimism is a choice. Kindness is a choice. Giving is a choice. Respect is a choice. Whatever choice you make makes you. Choose wisely.”
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    Quote Originally Posted by Paul Evans View Post
    So........

    Cost
    Time
    Space
    Safety

    Even with a cascade your going to lose gas.
    Without a booster or compressor you can never actually fill anything to 232. 300bar is out.
    Its much quicker to run a compressor.
    Its much safer to run a compressor.

    And thats just Air...................

    I'm with you about getting a compressor.

    Except why is decanting Nitrogen unsafe?
    No risk of oil contamination, much less heat of compression, no risk of sucking in vehicle fumes, no risk of an oxygen fire decanting it. If anything the only increased risk is doing your back in moving an extra J cylinder.

    Time? Really? A toy compressor will take 20 minutes to do your air top. From a bank (of nitrogen) you could do that in 20 seconds if you wanted. (ok let's not start on the time taken to go and get the J of nitrogen)


    BUT

    If you actually want to do it, then get your N2 from Energas as they do inerts at 300bar.

    You will need the daft euro coupling which may be different from the helium one but I don't know.
    Last edited by WFO; 13-06-2019 at 08:42 AM.

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    Apart from the fire-explosion risk not being there with nitrogen, there is still the safety concern of doing anything with a compressed gas and the energy stored in it. When dodgy tanks fail being filled it’s not usually an O2 fire, it’s the stored energy and whatever defect in the tank.

    If you are blending the N2 into oxygen, then there could then be a risk if the N2 is contaminated, and it meets high pressure O2

    I wonder if heat from decanting N2 into say 40 bar of pure O2 is dangerous if done quickly - tyres filled with air on large mining trucks explode with heat? Anyone know?

    If you want to blend, do it at ambient in your back with a Rebreather. Why settle for air though?


    Sent from my iPhone using Tapatalk

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    It would work but I can see no practical application for it in recreational diving.

    If it's more than a one off, you're very quickly going to lose the high pressure in your banked gasses so you'll need a booster.

    You're decanting o2 which comes with the obvious risks.

    There's also a monumentally increased risk of a fuck up leading to a hypo / hyperoxic mix.

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    Established TDF Member taz's Avatar
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    Quote Originally Posted by Dave1w View Post
    Apart from the fire-explosion risk not being there with nitrogen, there is still the safety concern of doing anything with a compressed gas and the energy stored in it. When dodgy tanks fail being filled it’s not usually an O2 fire, it’s the stored energy and whatever defect in the tank.

    If you are blending the N2 into oxygen, then there could then be a risk if the N2 is contaminated, and it meets high pressure O2

    I wonder if heat from decanting N2 into say 40 bar of pure O2 is dangerous if done quickly - tyres filled with air on large mining trucks explode with heat? Anyone know?

    If you want to blend, do it at ambient in your back with a Rebreather. Why settle for air though?


    Sent from my iPhone using Tapatalk
    Is it safer to always blend into the O2?
    Cause I never thought of that side off it

    taz

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    .. ... -. .----. - / -- --- .-. ... . / -.-. --- -.. . / --. --- --- -..


 
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