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Depleting the ozone layer?


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  1. #1
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    Depleting the ozone layer?

    I keep thinking about the old cold power rockets. I never got to try one back in the day but I always wanted to. The other day I walked into Walmart and purchased a kit to do a self recharge of the air conditioning unit on my car. Seems to me you could release a lot of R-134a ( correct designation ??) into the air with one of these if you weren't careful. Now I know that cold power rockets using freon are never coming back but something bugs me about this whole "depletion of the ozone layer" thing. Every time you have a thunderstorm and lightning, it creates ozone. At least according to my late Father it does. So where does that ozone go? Are we depleting it faster than it's created? Not trying to start an environmental debate or some sort of controversy here but this question about lightning and ozone has always bugged me. If I disappear from the forum, you guys will know that Al Gore's minions have come and taken me away!
    B.A.R.
    NAR # 94917

  2. #2
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    Well the R-134a is safer for the ozone layer that the old R-12 that had ozone eating CFC's (CloroFluoroCarbons) in it. That is the reason it replaced R-12. Either way it is not good for the environment.

    When all else fails.... Read the directions!
    If it don't fit.... Get a bigger hammer!
    Having peace of mind, means finding that piece!

  3. #3
    r134a depletes ozone, but a lot less than the old r12. it's also a more efficient coolant pound for pound.

    ozone (O3) is made by a multitude of things happening, including lightning, and UV radiation from the sun. it's a very powerful oxidiant, and will react with most organic material (that includes humans).

    ozone only lasts for a half hour to 45 minutes though, so it's constantly being created/depleted.

  4. #4
    Ozone O3 is constantly being made in the atmosphere by thunderstorms, like you said, and other processes. And it is alos constatnly being converted back into oxygen gas O2 by other processes. It takes some time on average to convert back to oxygen gas, and there is always some ozone around in an equilibrium state. Man-made gases like freon contain halogens like chlorine, and as they are broken down in the atmosphere, they release free atomic chlorine into the atmosphere. This chlorine acts as a catalyst and provides another process for converting ozone back into oxygen gas. Because it speeds up the average rate of converting ozone to oxygen gas, the new equilibrium state for ozone is lower than it would be otherwise --- meaning the level of ozone is depleted.

    The real serious problem with the ozone-depeleting gases is that they can stay around for a very long time, and the atomic chlorine they release into the atmosphere can also stay around a long time. It acts as a catalyst, so it is not used up in the chemical reaction that destroys the ozone --- it remains unchanged in the process and each chlorine atom is free to destroy hundreds (thousands? millions?) of ozone molecules in it's lifetime.

  5. #5
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    Ozone is highly reactive and near ground level where there is plenty to react with, short lived (I won't get into the chemical details). The big problem with the CFCs and other compounds, mostly to a much lesser degree, is that they catalyticly decompose ozone in the upper atmosphere. Meaning one molecule of CFC can facilitate the degredation of many molecules of ozone before it is rendered harmless.

    On a related note, one of the dryest people I've ever met was Sherwood Rowland (won the Nobel prize along with his postdoc Molina for explaining ozone depletion). A group of us took him out for dinner after a talk at a really nice restaurant with an insane wine selection and the chemistry department's credit card...oh the possibilities. We sat down at the bar and he order and O'Douls and announced he was a T-totaler. There was much sadness.

    That being said he is a tremendous scientist, who was the brunt of a tremendous attack campaign when his research on ozone depletion was coming out.
    Last edited by Cl(VII); 2nd August 2013 at 03:06 AM.

  6. #6
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    Quote Originally Posted by RocketMike View Post
    I keep thinking about the old cold power rockets. I never got to try one back in the day but I always wanted to. The other day I walked into Walmart and purchased a kit to do a self recharge of the air conditioning unit on my car. Seems to me you could release a lot of R-134a ( correct designation ??) into the air with one of these if you weren't careful. Now I know that cold power rockets using freon are never coming back but something bugs me about this whole "depletion of the ozone layer" thing. Every time you have a thunderstorm and lightning, it creates ozone. At least according to my late Father it does. So where does that ozone go? Are we depleting it faster than it's created? Not trying to start an environmental debate or some sort of controversy here but this question about lightning and ozone has always bugged me. If I disappear from the forum, you guys will know that Al Gore's minions have come and taken me away!
    The kicker is the "upper atmosphere" part. Ozone is naturally created by ultraviolet light. When short-wave UV light hits regular oxygen it breaks the molecule apart into atomic oxygen. The two newly-freed oxygen atoms are then able to find other oxygen molecules and combine with them to form ozone. Medium-wave UV light is absorbed by ozone - it breaks the ozone apart, which becomes regular molecular oxygen and a free oxygen atom. The atom can then find another regular molecule to form ozone, or hook up with an atom and become molecular oxygen again.

    Chlorine and Bromine enter the picture by catalytically converting ozone back to oxygen - they do so without reacting (so they're available to do it many times), and they destroy the ozone much quicker than it can be created.

    The types of UV are important here - UVA, UVB, and UVC. You hear about UVA and UVB all the time in sunscreen commercials. UVA is long-wave UV, which isn't blocked by the ozone layer. UVC is the short-wave UV, which is the type absorbed by oxygen, so depletion of the ozone layer doesn't let more of this in. UVB is the medium-wave stuff that's blocked by ozone, and coincidentally a major factor in sunburn and skin cancer.

    CFCs enter the picture because they belong to a group of molecules called "Halocarbons." Halocarbons are carbon-based molecules that have one or more halogen atoms bound to them. Fluorine, chlorine, and bromine are halogens. (Iodine is, too, but to my knowledge nobody has used it for refrigerants). Fluorine bonds extremely tightly to carbon, so it won't come off in the upper atmosphere, and can't participate in ozone depletion. This is why modern refrigerants (R-134a and many others) only use fluorine. Chlorine and bromine come off of a halocarbon molecule relatively easily, so when they reach the upper atmosphere they can effectively 'detach' from their host molecule and go play with the ozone. CFC-based refrigerants (Freon, also known as R-12) had chlorine. Bromine was usually used in fire suppression - Halon being the big usage.

    SO back to the original question: why ozone created at ground level doesn't help. Other people have answered this already, but I'll repeat: it's just too darned reactive to stick around long enough to do any good. Plus, since it's destroyed in the act of absorbing UVB radiation, and it can only be regenerated (in any significant quantity) by UVC radiation, it's not going to be regenerated at ground level.

    It's also really nasty stuff - strong oxidizing agents really aren't good for you. It's actually beneficial in some ways, though - white blood cells produce it as a means to rapidly destroy bacteria or other things they don't like.

    And just in case you thought the new refrigerants were great... they're all STRONG greenhouse gases. Way more powerful than CO2. So you just can't win.
    NAR 82268 L1

    "For any successful technology, reality must take precedence over public relations, for nature cannot be fooled."

  7. #7
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    Anyboby see that caboose go by----I lost my train of thought again!

  8. #8
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    Propane can be used as a substitute for R-12. Another thing that might work is the stuff used in canned air.
    'Til next time,

    Mike Toelle

    NAR 31692 L1

    SAM 0373

  9. #9
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    I appreciate the detailed explanations guys. Makes a good bit more sense to me now. I was not advocating anything to cause more environmental harm, it just bugged me because I could always remember my Dad remarking about the ozone after a thunderstorm. It is ashamed there is not a viable substitute for freon in cold power rockets though. I mean, we are lucky to have the motor options we have now but the novelty of cold power has always interested me. I don't think propane is a viable substitute, one spark and that's all she wrote! I have some canned air here and it's marked as flammable too. I don't think anything that's flammable is gonna fly.....excuse the pun.
    B.A.R.
    NAR # 94917

  10. #10
    Dr Zooch uses airbrush propellant in old coldpower engines. See:

    http://rocketdungeon.blogspot.com/20...ketry.html?m=1

  11. #11
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    Quote Originally Posted by 5x7 View Post
    Dr Zooch uses airbrush propellant in old coldpower engines. See:

    http://rocketdungeon.blogspot.com/20...ketry.html?m=1
    Unfortunately, I can't afford folks asking price for the old cold power engines. I wish someone would manufacture a modern day equivalent.
    B.A.R.
    NAR # 94917

  12. #12
    Hi everybody...
    I don't know why they don't just go back to using NH3 ammonia gas as a refrigerant. If memory serves me correct, ammonia is one of the best refrigerants known because of it's high heat absorbsion ability. Yes, I know it's poisonous, but there are ways to work around that.
    I still think that the expiration of Dupont's patents on the old Freon played a factor in it being banned.
    Daniel

  13. #13
    Butane and propane have been used in coldpower motors

  14. #14
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    Quote Originally Posted by DanFrank View Post
    Hi everybody...
    I don't know why they don't just go back to using NH3 ammonia gas as a refrigerant. If memory serves me correct, ammonia is one of the best refrigerants known because of it's high heat absorbsion ability. Yes, I know it's poisonous, but there are ways to work around that.
    I still think that the expiration of Dupont's patents on the old Freon played a factor in it being banned.
    Daniel
    If you've ever messed with anhydrous ammonia, you'd understand...

    "Poisonous" isn't really the word... the stuff is, being a pressurized liquid, prone to boiling off instantly into clouds of white vapor when the pressure is removed from it, absorbing heat and thus "refrigerating" whatever it touches in the process (which can frostbite you if you're sprayed with the liquid itself, much like propane or butane.) The clouds of gas are noxious, in that if you breathe them in, or the vapors get into your eyes, they are hygroscopic, meaning "water seeking" and thus dissolve instantly in the moisture in your eyes and mucous membranes, like inside your nose, throat, and lungs. This is roughly analgous to inhaling liquid household floor-mopping ammonia (aqueous ammonia). In short, it's like you snorted a bottle of household ammonia and you start drowning in the stuff... no good at all!

    My Dad was very nearly gassed by anhydrous ammonia, which is commonly used as an agricultural nitrogen fertilizer, when I was a kid. After that, despite anhydrous being cheaper, he switched to the more expensive but much safer to handle aqueous ammonia, which is ammonia already dissolved in water as a carrier, and thus is not a pressurized liquid that boils in open air, and isn't stored in a pressure tank. Worst that could happen to you with that stuff was getting it in an open cut, where it'd burn like fire, or having it splash you on your skin, tongue, or eyes, where it behaved similar to household cleaning ammonia-- IOW a strong detergent, tasted terrible, and burned in the eyes until it was washed away by eye flushing, and might dry your skin out.

    While folks have used propane or butane to as a cheap replacement for R-12, it's certainly NOT a recommended practice... (though an often necessary one, since R-12 substitutes were non-existant or heavily regulated as well). Refrigerants are supposed to be formulated to be non-toxic (at least at the "normal" levels one would expect if an accident punctured the coils and caused an "instantaneous" release of all the refrigerant in the particular system that was punctured, whether automotive or appliance), and it's supposed to be non-flammable, or not support combustion. Ammonia and propane/butane of course don't meet these requirements (though ammonia is a severe irritant and not massively, instantly "toxic" per-se, though it is in large enough concentrations). Honestly, I'd be less afraid of propane as a refrigerant than ammonia, especially in a vehicle-type system... a couple pounds of propane, even vented suddenly by a punctured coil, would basically have to vent and mix with air directly in the presence of an ignition source to ignite... and if the mixture is off, meaning not enough oxygen, or too diluted by mixing with too much air, the stuff won't ignite at all, and even if it does, it would burn off very quickly. Ammonia, on the other hand, would be an inhalation hazard until the wind finally carried it away. In a stationary air conditioning or refrigeration system, I wouldn't want either one...

    I've handled propane and butane, as it used to be a very popular (and cheap) alternative (in the 1950's) to gasoline power in farm tractors, before the 'diesel revolution' in the late 60's took hold and basically ALL farm equipment became diesel powered in the early 70's... We had a propane-powered Golden Jubilee Ford when I was a kid, and a propane powered Farmall M several years ago. One day I was filling it from the bulk propane tank, and when I disconnected the fill valve, the automatic poppet valve on the tractor tank, which is supposed to snap shut when the bulk tank hose fitting is unscrewed, stuck... liquid propane started squirting out, and rapidly boiling off into vapor, and soon the parts were thoroughly frosted over, their latent heat being siphoned off by the boiling propane. I tried screwing the valve back on, but couldn't get it to reseal... soon it was too bitterly cold to work with in bare hands, so I went and got my heavy leather welding gloves and used them, but they would soak up liquid propane which would boil off and soon they were freezing up too... I finally managed to get the fill hose unscrewed, and the poppet valve continued to dribble liquid propane, which boiled off into a cloud of vapors that then drifted across the field from our house toward the highway, some 150 yards away, and I was worrying that someone might toss a lit cigarette out a car window and have a gas explosion that would backdraft along the fumes to the tractor and tank, as the vapor cloud drifted on the breeze across the field. I got a 2x4 board and started smacking the sides of the tank filler fitting (the steel fitting welded to the tank into which the brass poppet filler valve was screwed) and it FINALLY snapped shut and seated, shutting off the flow of liquid propane, and the vapors rapidly dispersed... problem solved. My Dad told me later that yeah, sometimes that happens, and yeah, that's how you fix it...

    Later! OL JR
    The X-87B Cruise Basselope- THE ultimate weapon in the arsenal of homeland defense and only $52 million per round!

  15. #15
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    Quote Originally Posted by DanFrank View Post
    Hi everybody...
    I don't know why they don't just go back to using NH3 ammonia gas as a refrigerant. If memory serves me correct, ammonia is one of the best refrigerants known because of it's high heat absorbsion ability. Yes, I know it's poisonous, but there are ways to work around that.
    I still think that the expiration of Dupont's patents on the old Freon played a factor in it being banned.
    Daniel
    Ammonia is a great refrigerant. They even use it on the space station, despite the toxicity, because it's just the best stuff for the job. But that's a well-maintained system which is designed to some pretty stringent safety standards, not the least of which is that the ammonia never comes close to the crew volume. Residential A/C units aren't exactly well-maintained, though, and it's kind of dangerous to have your A/C system leak a poisonous, flammable gas into your house.

    There were no patents on Freon which expired around the time of the Montreal Protocol. R-12 (what we commonly call Freon) was invented in the late 1800s. "Freon" is the trademarked name DuPont sold it under, and trademarks don't expire (as long as they're protected by the holder).
    NAR 82268 L1

    "For any successful technology, reality must take precedence over public relations, for nature cannot be fooled."

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