This one seems to cause some very negative comments.

[spiral_72]

Alright, I've got this idea. Boy, that sounds like the beginning to an
end.

I figure I can drop dry ice in a tank, cap it with a regulator and have
CO2 for some period of time for my planted aquarium. Obviously it will
require more than a handful of dry ice and chances are it ain't quite
that simple. Right now I am building a tank with a mouth wide enough to
accept an entire piece. I figger I'll pack the stuff in there like the
old shotgun wadding with a length of 2x2 or something until it's full,
and cap it.

I run a search on this over the web and the Google groups. I got the
same response: "DON'T DO IT, IT'S TOO COMPLICATED"

What's up with dat? Any particular reason? I don't want to hear that
the stuff is not sanitary either. The air in my house probly ain't
sanitary after a nice homemade bowl of chille. Heck, it's free......
They pack ice cream in it at the gas station (they sell ice cream in
cones) and they just throw it away.

[Pete]

"spiral_72" > wrote in news:1106256969.936458.265300
@c13g2000cwb.googlegroups.com:

> Alright, I've got this idea. Boy, that sounds like the beginning to an
> end.
>
> I figure I can drop dry ice in a tank, cap it with a regulator and have
> CO2 for some period of time for my planted aquarium. Obviously it will
> require more than a handful of dry ice and chances are it ain't quite
> that simple. Right now I am building a tank with a mouth wide enough to
> accept an entire piece. I figger I'll pack the stuff in there like the
> old shotgun wadding with a length of 2x2 or something until it's full,
> and cap it.
>
> I run a search on this over the web and the Google groups. I got the
> same response: "DON'T DO IT, IT'S TOO COMPLICATED"
>
> What's up with dat? Any particular reason? I don't want to hear that
> the stuff is not sanitary either. The air in my house probly ain't
> sanitary after a nice homemade bowl of chille. Heck, it's free......
> They pack ice cream in it at the gas station (they sell ice cream in
> cones) and they just throw it away.
>
>

Actually sounds like fun but a few of the things I can think of off hand.

1. I'm not sure if you'll get enough pressure to run a regulator. I've
heard many horror stories of regulators allowing CO2 dumps into tanks
because they let their CO2 tank get too low and thus not enough pressure
for the regulator to work with, the remaining CO2 gets injected overnight
and game over.

2. If you do get enough pressure for a regulator, how good are you at
building high pressure tanks? I don't think you want any sort of explosion
near a large glass tank filled with water.

3. If you rely on the speed of it melting to dictate the injection rate
(maybe a setup with a insulated box for the ice and an air tube to the
intake of a canister filter) then it's an issue of controling the speed.
You could change that with using more or less insulation and I could see
that maybe working.. no worse that yeast and sugar for varing rates.

P.

[Dan White]

> "spiral_72" > wrote in news:1106256969.936458.265300
>
> 3. If you rely on the speed of it melting to dictate the injection rate


Just a nitpick, but CO2 sublimes instead of melts.

dwhite

[Pete]

"Dan White" > wrote in news:0t%Hd.571$vo6.564
@fe11.lga:

>> "spiral_72" > wrote in news:1106256969.936458.265300
>>
>> 3. If you rely on the speed of it melting to dictate the injection rate
>
>
> Just a nitpick, but CO2 sublimes instead of melts.
>
> dwhite
>
>
>

ROTFLMAO. Oh man I know, I'm a science geek I do that nitpicking stuff
myself. I just didn't think it was worth it having people look up the
definition of sublimation :P

P.

[Dan White]

"Pete" > wrote in message
...
> "Dan White" > wrote in news:0t%Hd.571$vo6.564
> @fe11.lga:
>
> >> "spiral_72" > wrote in
news:1106256969.936458.265300
> >>
> >> 3. If you rely on the speed of it melting to dictate the injection rate
> >
> >
> > Just a nitpick, but CO2 sublimes instead of melts.
> >
> > dwhite
> >
> >
> >
>
> ROTFLMAO. Oh man I know, I'm a science geek I do that nitpicking stuff
> myself. I just didn't think it was worth it having people look up the
> definition of sublimation :P
>
> P.

Like they say, "Damned if you do, damned if you don't." :)

dwhite

[spiral_72]

What I am hoping:

The dry ice will sublimate inside the tank, building pressure. At some
point the pressure will be high enough inside the tank that this
process stops (untill you leak a little CO2 into the aquarium.

At what pressure does the CO2 reach this.......equilibrium? I have no
idea...... What's worse I don't know how to find out other than
experiment. So, with this in mind (don't laugh) I found some 6" OD,
1/4" wall seamless steel tube to which I am going to tig weld 1/4"
thick plate "plugs" to cap the tank. I Already have the round stock and
I have turned the caps on a lathe.......O.K. now you can laugh.

The tank weighs about 15lbs! and I figger it'l be good to about
Mmmmmmmm........275,000psi. In all seriousness, I'm not worried about
the weld till at least 1500psi. Irregardless, the first time I am going
to pressurize this "bomb" in the front yard.

What's really gonna suck, is if the CO2 sublimates to 15psi....at which
point it reaches this "equilibrium" and I now have a very interesting
looking boat anchor. I guess lucky enough for me I pulled all this
stuff out of the dumpster at work. So, so far it hasn't cost any money.

Hey, this might even draw a crowd! Maybe, I could charge
admission!!.............Maybe, not.

[spiral_72]

Well, if I figured this right:

P = n * R * T / V Where:

P = pressure in atm
n = amount of substance in moles
R = Thermal expansion ( 1atm / K*mol )
T = Temp change in Kelvins
V = Volume of a sealed container in Liters

( n ) for CO2 is 22.727mol
( R ) for CO2 is 0.08206
( T ) is 298K
( V ) is 6.81322 Liters

Ignoring the air present in the container when it was sealed, and
introducing 1 Kg (2.2lbs) of dry ice in my 6.813 L tank, while the air
in my living room is 24 C (75 F)
final pressure inside the tank will be 8238.7 psi.

Oh, crap.

[Pete]

"Dan White" > wrote in
:

> "Pete" > wrote in message
> ...
>> "Dan White" > wrote in news:0t%Hd.571$vo6.564
>> @fe11.lga:
>>
>> >> "spiral_72" > wrote in
> news:1106256969.936458.265300
>> >>
>> >> 3. If you rely on the speed of it melting to dictate the injection
>> >> rate
>> >
>> >
>> > Just a nitpick, but CO2 sublimes instead of melts.
>> >
>> > dwhite
>> >
>> >
>> >
>>
>> ROTFLMAO. Oh man I know, I'm a science geek I do that nitpicking
>> stuff myself. I just didn't think it was worth it having people look
>> up the definition of sublimation :P
>>
>> P.
>
> Like they say, "Damned if you do, damned if you don't." :)
>
> dwhite
>
>

Hey, just thought of something. CO2 in a pressured tank is in liquid form.
So if he puts this dry ice in a sealed tank that does get a high enough
pressure once enough CO2 has sublimated, as the rest of the CO2 thaws it
will turn into a liquid instead of a gas... so it would 'melt'. hehe.

P.

[Pete]

"spiral_72" > wrote in news:1106326353.925305.265280
@z14g2000cwz.googlegroups.com:

> Well, if I figured this right:
>
> P = n * R * T / V Where:
>
> P = pressure in atm
> n = amount of substance in moles
> R = Thermal expansion ( 1atm / K*mol )
> T = Temp change in Kelvins
> V = Volume of a sealed container in Liters
>
> ( n ) for CO2 is 22.727mol
> ( R ) for CO2 is 0.08206
> ( T ) is 298K
> ( V ) is 6.81322 Liters
>
> Ignoring the air present in the container when it was sealed, and
> introducing 1 Kg (2.2lbs) of dry ice in my 6.813 L tank, while the air
> in my living room is 24 C (75 F)
> final pressure inside the tank will be 8238.7 psi.
>
> Oh, crap.
>
>

Well look on the bright side, if your tank doesn't hold, your manner of
death will be posted on the next list of the Darwin Awards :P

P.

[Richard Sexton]

>Oh, crap.

Now you know why you haven't heard of this before. :-)



--
Need Mercedes parts ? - http://parts.mbz.org
http://www.mbz.org | Mercedes Mailing lists: http://lists.mbz.org
633CSi 250SE/C 300SD | Killies, killi.net, Crypts, aquaria.net
1970 280SE, 72 280SE | Old wris****ches http://watches.list.mbz.org

[Ross Vandegrift]

On 2005-01-21, spiral_72 > wrote:
> Ignoring the air present in the container when it was sealed, and
> introducing 1 Kg (2.2lbs) of dry ice in my 6.813 L tank, while the air
> in my living room is 24 C (75 F)
> final pressure inside the tank will be 8238.7 psi.
>
> Oh, crap.

Well, the problem I can think of, even if you put less in:

CO2 is heavier than air. So if the pressure isn't high enough,
it'll just sit in your bottle and not do anything fun or interesting.

On the other hand, that strikes me as a better idea than winning a
Darwin award, as one poster suggested... ::-)


--
Ross Vandegrift

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37

[spiral_72]

HA, ha...... go ahead and laugh, Ye' of little faith.

My idea just may revolutionize the aquarium hobby as we know it. Quite
possibly the WORLD!

Anyways....... I bought some dry ice at Publix (a grocery store) for
$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
I suppose......Screwed the top on and um, hehe It went from a coke
bottle shape.... to a um, round kinda shape and all the pleats in the
bottle pulled out.......That is untill it exploded.

So, cool I know it works..... Guess I'll start out small and monitor it
with a pressure gauge.

Oh, yea....... Kids, Don't try that at home......... And if you do.....
leave me a message and tell me that wasn't the most excitement you've
had since breakfast.

[Richard Sexton]

In article . com>,
spiral_72 > wrote:
>Anyways....... I bought some dry ice at Publix (a grocery store) for
>$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
>a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
>I suppose......Screwed the top on and um, hehe It went from a coke
>bottle shape.... to a um, round kinda shape and all the pleats in the
>bottle pulled out.......That is untill it exploded.

Hey if you like that you should try to find the webpage
that has the videos of a guy dropping one pound blcoks
of pure sodium metal into water. That makes a nice bang too
with the added benefit of throwing molten metal and
lye all over the place.

--
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1970 280SE, 72 280SE | Old wris****ches http://watches.list.mbz.org

[Pete]

(Richard Sexton) wrote in :

> In article . com>,
> spiral_72 > wrote:
>>Anyways....... I bought some dry ice at Publix (a grocery store) for
>>$1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
>>a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
>>I suppose......Screwed the top on and um, hehe It went from a coke
>>bottle shape.... to a um, round kinda shape and all the pleats in the
>>bottle pulled out.......That is untill it exploded.
>
> Hey if you like that you should try to find the webpage
> that has the videos of a guy dropping one pound blcoks
> of pure sodium metal into water. That makes a nice bang too
> with the added benefit of throwing molten metal and
> lye all over the place.
>

There's one around!??!! Oh man I remember wishing that ever since high
school chemistry class. Our teacher has this huge chunk of sodium (kept
in oil) and he only gave us a tiny chunk to put into a beaker of water
to watch the reaction. I always wanted to get my hands on that chunk
and put it in a swimming pool... or how about a bucket of chlorine. If
sodium reacts that well with H2O I'm sure it would be dandy with CL for
a quick reaction to NACL :P


Actually spiral, I might have a safe (if less exciting) way for your
idea to work. Since all you want to do is have a consistant amount of
CO2 going into your tank, you need a reactor that is consistant but
doesn't build up pressure.

If you have an open bottomed box submerged in your tank with an air hose
from it to your CO2 tank (no valve), the amount of CO2 going into your
tank would depend on the size of the box (the surface area of the open
side). Excess CO2 produced would eventually overflow the box and bubble
up so no explosion risk.

If you find you're not getting enough CO2 dissolving into your tank
water, just get a bigger box which will have a bigger surface area for
the CO2 to react and dissolve into the water. I believe putting it
deeper also works.

Once you have the right size and getting 20-30 ppm of CO2 in your tank,
if you find you're wasting too much CO2 (it's bubbling out of the box)
just insulate the CO2 container more to slow it down.. you should be
able to get a pretty close balance so little CO2 is wasted.

Only problem with this method would be if the CO2 sublimates so quickly,
even with insulation that you waste too much of it.


All that being said, it might be easier and cheaper (unless you get some
free dryice) to go the yeast/sugar DIY co2 method which also has been
known to blow up bottles if that's a must :P

Cheers
P.

[Dan White]

"Pete" > wrote in message
...
> "Dan White" > wrote in
> :
>
> > "Pete" > wrote in message
> > ...
> >> "Dan White" > wrote in news:0t%Hd.571$vo6.564
> >> @fe11.lga:
> >>
> >> >> "spiral_72" > wrote in
> > news:1106256969.936458.265300
> >> >>
> >> >> 3. If you rely on the speed of it melting to dictate the injection
> >> >> rate
> >> >
> >> >
> >> > Just a nitpick, but CO2 sublimes instead of melts.
> >> >
> >> > dwhite
> >> >
> >> >
> >> >
> >>
> >> ROTFLMAO. Oh man I know, I'm a science geek I do that nitpicking
> >> stuff myself. I just didn't think it was worth it having people look
> >> up the definition of sublimation :P
> >>
> >> P.
> >
> > Like they say, "Damned if you do, damned if you don't." :)
> >
> > dwhite
> >
> >
>
> Hey, just thought of something. CO2 in a pressured tank is in liquid form.
> So if he puts this dry ice in a sealed tank that does get a high enough
> pressure once enough CO2 has sublimated, as the rest of the CO2 thaws it
> will turn into a liquid instead of a gas... so it would 'melt'. hehe.
>

Hmmm, well I'm not so sure it would work quite like that, but maybe! Vapor
pressure diagrams were a long time ago.

dwhite

[Dan White]

"spiral_72" > wrote in message
oups.com...
> Well, if I figured this right:
>
> P = n * R * T / V Where:
>
> P = pressure in atm
> n = amount of substance in moles
> R = Thermal expansion ( 1atm / K*mol )
> T = Temp change in Kelvins
> V = Volume of a sealed container in Liters
>
> ( n ) for CO2 is 22.727mol
> ( R ) for CO2 is 0.08206
> ( T ) is 298K
> ( V ) is 6.81322 Liters
>
> Ignoring the air present in the container when it was sealed, and
> introducing 1 Kg (2.2lbs) of dry ice in my 6.813 L tank, while the air
> in my living room is 24 C (75 F)
> final pressure inside the tank will be 8238.7 psi.
>
> Oh, crap.

I get about 1200 psi. Your formula gives you about 81 atm. 1 atm = 14.7
psi.

You should be fine if you go with 1" thick steel. :)

dwhite

[Elaine T]

spiral_72 wrote:
> HA, ha...... go ahead and laugh, Ye' of little faith.
>
> My idea just may revolutionize the aquarium hobby as we know it. Quite
> possibly the WORLD!
>
> Anyways....... I bought some dry ice at Publix (a grocery store) for
> $1.09 a pound.... Cheap enough I guess. I put about 1 inch of water in
> a 20oz coke bottle and 3 pieces of dry ice about the size of a quarter
> I suppose......Screwed the top on and um, hehe It went from a coke
> bottle shape.... to a um, round kinda shape and all the pleats in the
> bottle pulled out.......That is untill it exploded.
>
> So, cool I know it works..... Guess I'll start out small and monitor it
> with a pressure gauge.
>
> Oh, yea....... Kids, Don't try that at home......... And if you do.....
> leave me a message and tell me that wasn't the most excitement you've
> had since breakfast.
>
Heh. You haven't been around a biology lab enough. We used to take dry
ice pellets and put them in latex gloves. Tie the end in a knot and
stick the glove over by someone. It eventually blows up into a balloon,
and pops. *bang* Everyone jumps.

Juvenile, but hey - graduate school brings out the best in everyone. ;-)

--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><

[spiral_72]

Hey, you know what? You are right..... I went back and checked my
little engineer's book........ 1atm=14.7psi.......not 101.3psi
Thank you. If nothing else it makes me feel better about my tank

[Dan White]

"spiral_72" > wrote in message
oups.com...
> Hey, you know what? You are right..... I went back and checked my
> little engineer's book........ 1atm=14.7psi.......not 101.3psi
> Thank you. If nothing else it makes me feel better about my tank
>

Sure. You gonna give it a try?

dwhite

[Morten]

"spiral_72" > wrote in message
oups.com...
> Alright, I've got this idea. Boy, that sounds like the beginning to an
> end.
>
> I figure I can drop dry ice in a tank, cap it with a regulator and have
> CO2 for some period of time for my planted aquarium. Obviously it will
> require more than a handful of dry ice and chances are it ain't quite
> that simple. Right now I am building a tank with a mouth wide enough to
> accept an entire piece. I figger I'll pack the stuff in there like the
> old shotgun wadding with a length of 2x2 or something until it's full,
> and cap it.
>
> I run a search on this over the web and the Google groups. I got the
> same response: "DON'T DO IT, IT'S TOO COMPLICATED"
>
> What's up with dat? Any particular reason? I don't want to hear that
> the stuff is not sanitary either. The air in my house probly ain't
> sanitary after a nice homemade bowl of chille. Heck, it's free......
> They pack ice cream in it at(they sell ice crea the gas station m in
> cones) and they just throw it away.


I can see what you're trying to do and I can see the fun in trying it, but
unless you're very good with a tig welder I wouldn't try that at all, I
really dont fancy my liver being spread over to large an area, it's just
fine where it is now.


If the goal of this exercise is to supply a steady stream of CO2 which can
be easily regulated / shut off, why don't you use a setup using baking soda
(NaHCO3) and a suitable acid like HCL or vinegar if you're a pussy :-)


I can't remember where I saw this but a setup with a couple of containers,
one with the acid in a ballon in a slightly presurized container, say 0.1bar
(1m water column), with a hose comming from the ballon to the next container
that contains the bakingpowder with about 2-3 cm of water on top (it wont
all disolve right away but will when the concetration goes down after time)
and another hose comming out to you tank, bubler, regulator whatever...

The theory is that when you add the acid to the saturated bakingpowder
solution the reaction releases CO2 which increases the pressure thus
preventing more acid to flow into the mixing container. When some of the CO2
is used the pressure will drop, allowing some acid to drip into the main
reactor, reacting with some baking powder thus creating some more CO2 until
the pressure reaches a equilibrium at arround the 0.1 bar mark...

The potential yield of this would be quite large, ie. pretty much governed
bu how fast you can supply the acid and how fast the CO2 gas can be used. On
the other hand you should be able to stop using any CO2 at all and the
reaction should stop itselfe because the pressure gets to high for any more
acid to flow into the main reactor and nothing more happens.

It would probably be a good idea to include a oneway valve in the hose
comming from the acid container and oanother in the hose comming from the
main reactor and a couple of stop valves would probably be called for as
well....


The chemical reaction is:

NaHCO3(aq) + HCl(aq) => CO2(g) + H20(aq) + NaCL(aq) + energy


I haven't build this one yet, but where I live baking powder is dirt cheap
and so is the HCl, one could use other acids if no HCl is available.

I would think that standard PVC drain fittings could be used, the pressure
is well within reach of standard schedule40 pipes and fittings, but one
could use schedule80 if paranoid. the hoses could be solicone of standard
vinyl hoses, as long as they're monitored close they should be fine...


What do you think, Is this approach even more insane than the Dry Ice in
container method, as far as I can see it should work just fine, just haven't
hade the time to source some materials yet...

/Morten




---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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[Morten]

"Morten" > wrote in message
...
>
> "spiral_72" > wrote in message
> oups.com...
> > Alright, I've got this idea. Boy, that sounds like the beginning to an
> > end.
>
> The chemical reaction is:
>
> NaHCO3(aq) + HCl(aq) => CO2(g) + H20(aq) + NaCL(aq) + energy
>

I've done a few calculations and 100g of baking powder together with 0.1447
litre of 30%HCl should give 52.39g CO2 which at room temperature / pressure
should be arround 26.65 Litre of CO2 gas which in turn should be about 2540
bubbles (based on a bubble size of 0.0952ml)

I also did some calculation on the yeast / sugar method and found that 200g
sugar gave about 48.86g CO2 or 24.87 Litre CO2 at room temperature, which is
about 2368 bubbles given the same bubble size as above...

So say that we use a standard Yeast / Sugar batch of ca. 200g sugar that
gives ca. 4700 bubbles over ca. 2 weeks. The Baking powder / Acid mix will
give approximately the same, but because the reaction is self regulating we
can make much bigger batches, ie. we could use 500g of baking powder and
0.723Litre of 30% HCl that would give 12700 Bibbles, lasting 37 days instead
of 14 days for a batch...


And of course the Baking powder / acid method can be shut off and run slow
or fast depending on need, where the yeast / sugar method cannot be
controlled easily with out venting / loosing the CO2 when not needed or
cleaning up the mess after a little mishap...


I still thinks this is a great idea, just haven't had a chance to implement
it yet.

Hmm, I wonder if B&Q are open now...



/Morten





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[Dan White]

"Morten" > wrote in message
...
>
> I've done a few calculations and 100g of baking powder together with
0.1447
> litre of 30%HCl should give 52.39g CO2 which at room temperature /
pressure
> should be arround 26.65 Litre of CO2 gas which in turn should be about
2540
> bubbles (based on a bubble size of 0.0952ml)
>
> I also did some calculation on the yeast / sugar method and found that
200g
> sugar gave about 48.86g CO2 or 24.87 Litre CO2 at room temperature, which
is
> about 2368 bubbles given the same bubble size as above...
>
> So say that we use a standard Yeast / Sugar batch of ca. 200g sugar that
> gives ca. 4700 bubbles over ca. 2 weeks.

It is an interesting idea, but I'm not sure if something sounds right or
not. I'm not a CO2 expert...I don't even use it, but I think I recall
people talking in terms of several bubbles per second. Even if we talk
about 1 bubble/sec over say 12 hours/day for 14 days that makes over 600,000
bubbles! Your bubble at .0952 ml has about a .28 cm radius, so it is a big
bubble.

I don't know how big the 600,000 bubbles are at the 1 bubble/sec rate, but
if we look at your calculation of 4700 bubbles through the yeast method over
that same 14 days, this would say that your bubbles would have to be
600K/4.7K = 128 times the volume of the yeast bubble. So what does that
make the radius of the 600,000 bubbles? .0952ml/128 = .00074 ml, or a
bubble radius of .056 cm or a diameter of 1 mm.

So for people who use yeast, if you get 1 bubble per second, these bubbles
would have to be 1 mm in diameter in order for the "charge" of yeast to last
14 days at 12 hours per day if Morten's 4700 bubble calculation is correct.
Does this make sense?

Just curious,
dwhite

[Morten]

"Dan White" > wrote in message
...
> It is an interesting idea, but I'm not sure if something sounds right or
> not. I'm not a CO2 expert...I don't even use it, but I think I recall
> people talking in terms of several bubbles per second. Even if we talk
> about 1 bubble/sec over say 12 hours/day for 14 days that makes over
600,000
> bubbles! Your bubble at .0952 ml has about a .28 cm radius, so it is a
big
> bubble.
>
> I don't know how big the 600,000 bubbles are at the 1 bubble/sec rate, but
> if we look at your calculation of 4700 bubbles through the yeast method
over
> that same 14 days, this would say that your bubbles would have to be
> 600K/4.7K = 128 times the volume of the yeast bubble. So what does that
> make the radius of the 600,000 bubbles? .0952ml/128 = .00074 ml, or a
> bubble radius of .056 cm or a diameter of 1 mm.
>
> So for people who use yeast, if you get 1 bubble per second, these bubbles
> would have to be 1 mm in diameter in order for the "charge" of yeast to
last
> 14 days at 12 hours per day if Morten's 4700 bubble calculation is
correct.
> Does this make sense?

To be totally honest the 0.0952ml per bubble was something i got from a
couple of postings a couple of years back, ie they came from a '1050 bubbles
per 100ml' statement, but your'e right it sounds like a quite a large bubble
:-) and is probably way above a real bubble, anyone done some counting on a
known volume?


/Morten




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[Elaine T]

Morten wrote:
> "spiral_72" > wrote in message
> oups.com...
>
>>Alright, I've got this idea. Boy, that sounds like the beginning to an
>>end.
>>
>>I figure I can drop dry ice in a tank, cap it with a regulator and have
>>CO2 for some period of time for my planted aquarium. Obviously it will
>>require more than a handful of dry ice and chances are it ain't quite
>>that simple. Right now I am building a tank with a mouth wide enough to
>>accept an entire piece. I figger I'll pack the stuff in there like the
>>old shotgun wadding with a length of 2x2 or something until it's full,
>>and cap it.
>>
>>I run a search on this over the web and the Google groups. I got the
>>same response: "DON'T DO IT, IT'S TOO COMPLICATED"
>>
>>What's up with dat? Any particular reason? I don't want to hear that
>>the stuff is not sanitary either. The air in my house probly ain't
>>sanitary after a nice homemade bowl of chille. Heck, it's free......
>>They pack ice cream in it at(they sell ice crea the gas station m in
>>cones) and they just throw it away.
>
>
>
> I can see what you're trying to do and I can see the fun in trying it, but
> unless you're very good with a tig welder I wouldn't try that at all, I
> really dont fancy my liver being spread over to large an area, it's just
> fine where it is now.
>
>
> If the goal of this exercise is to supply a steady stream of CO2 which can
> be easily regulated / shut off, why don't you use a setup using baking soda
> (NaHCO3) and a suitable acid like HCL or vinegar if you're a pussy :-)
>
>
> I can't remember where I saw this but a setup with a couple of containers,
> one with the acid in a ballon in a slightly presurized container, say 0.1bar
> (1m water column), with a hose comming from the ballon to the next container
> that contains the bakingpowder with about 2-3 cm of water on top (it wont
> all disolve right away but will when the concetration goes down after time)
> and another hose comming out to you tank, bubler, regulator whatever...
>
> The theory is that when you add the acid to the saturated bakingpowder
> solution the reaction releases CO2 which increases the pressure thus
> preventing more acid to flow into the mixing container. When some of the CO2
> is used the pressure will drop, allowing some acid to drip into the main
> reactor, reacting with some baking powder thus creating some more CO2 until
> the pressure reaches a equilibrium at arround the 0.1 bar mark...
>
> The potential yield of this would be quite large, ie. pretty much governed
> bu how fast you can supply the acid and how fast the CO2 gas can be used. On
> the other hand you should be able to stop using any CO2 at all and the
> reaction should stop itselfe because the pressure gets to high for any more
> acid to flow into the main reactor and nothing more happens.
>
> It would probably be a good idea to include a oneway valve in the hose
> comming from the acid container and oanother in the hose comming from the
> main reactor and a couple of stop valves would probably be called for as
> well....
>
>
> The chemical reaction is:
>
> NaHCO3(aq) + HCl(aq) => CO2(g) + H20(aq) + NaCL(aq) + energy
>
>
> I haven't build this one yet, but where I live baking powder is dirt cheap
> and so is the HCl, one could use other acids if no HCl is available.
>
> I would think that standard PVC drain fittings could be used, the pressure
> is well within reach of standard schedule40 pipes and fittings, but one
> could use schedule80 if paranoid. the hoses could be solicone of standard
> vinyl hoses, as long as they're monitored close they should be fine...
>
>
> What do you think, Is this approach even more insane than the Dry Ice in
> container method, as far as I can see it should work just fine, just haven't
> hade the time to source some materials yet...
>
>
HCl fumes badly in concentrated form, and I think I remember some fumes
from dilute HCl (haven't handled the stuff in a while). Same with
acetic acid for that matter. Wouldn't you tend to acidify the fishtank
some with acid fumes, or are they not concentrated enough to matter?

--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><

[spiral_72]

An update:

I welded the bottom plug into the tank Friday when I got home. Actually
I am quite pleased with the results. The penetration wasn't quite as
good as I would have liked to see (Man, that's some thick stuff!) but,
1200psi should be no sweat.

Saturday: made a trip to the hardware store.... I bought steel fittings
for the tank to the regulator, regulator to the hose.... I don't have a
needle valve yet..... This should be sufficient for now........... Oh,
and I bought a manual operated valve to blow off tank pressure. The
blow-off valve will be seperate from the regulator........ I bought a
big pipe cap.

I didn't have a drill and tap big enough for the pipe tap at home so
it'll have to wait untill I can di it at work. The cap is about 1 1/2 -
18 thread...... This is big but still much smaller than a chunk of dry
ice..... Guess I'll have to break it up into pieces eh?

Also, the hardware store did not have a pressure gauge that would read
2000psi...... Hopefully I can stop by the welder's supply on the way
home. Right now all I have is a 0-200psi low quality gauge and a nice
little gauge for my regulator (0-160psi I think).

[Morten]

"Elaine T" > wrote in message
m...
>
> >
> HCl fumes badly in concentrated form, and I think I remember some fumes
> from dilute HCl (haven't handled the stuff in a while). Same with
> acetic acid for that matter. Wouldn't you tend to acidify the fishtank
> some with acid fumes, or are they not concentrated enough to matter?

HCl does indeed fume a bit and so does the Acetic Acid (Vinegar), but the
acid is inside the ballon / drip bag inside the first container, and the
only way out of there is via ahose leading to the main reactor where it gets
neutralized / reacts with the baking powder and because you only draw off
the gas you should be fine. If you're to worried you could send the CO2 gas
through a bubble counter / water scrubber, that will take care of any stray
HCl / Acetic Acid molecules that might be in gas form inside the main
reactor.

So in fact there will be 4 containers, one which is open at the top with
water in it with a hose comming out of the bottom, the hose leads to the
acid in ballon container on the outside of the ballon, the hose from the
ballon goes through the bottom of the acid container and leads to the main
reactor which also contains the baking powder solution. From the main
reactor a small hose goes through a smaller container filled 2/3 with water
so that the co2 has to bubble through the water and out via another hose
above the water level and into tank diffuser / co2 reactor / valve /
whatever...


/Morten




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[Dan White]

"spiral_72" > wrote in message
ups.com...
> An update:
>
> I didn't have a drill and tap big enough for the pipe tap at home so
> it'll have to wait untill I can di it at work. The cap is about 1 1/2 -
> 18 thread...... This is big but still much smaller than a chunk of dry
> ice..... Guess I'll have to break it up into pieces eh?
>

Why not just melt the dry ice and pour it in? :o)

dwhite

[spiral_72]

Well, for anyone still following this post:

The tank is finished for the most part..... I am kinda stuck on a plug
or lid for the top. I bought a 1-1/2 inch pipe plug to use but I am
having a difficult time finding a tap big enough for it...... I guess I
could order one, but that's about $30 for something I'll never use
again.

Construction is going very good...... As soon as I can decide what to
do about the plug/lid I'll weld the top on it and try out "da bomb"

Oh, 4 pounds of dry ice keeps only 2 days inside an Igloo cooler inside
your freezer.

[Dan White]

"spiral_72" > wrote in message
oups.com...
> Well, for anyone still following this post:
>
> The tank is finished for the most part..... I am kinda stuck on a plug
> or lid for the top. I bought a 1-1/2 inch pipe plug to use but I am
> having a difficult time finding a tap big enough for it...... I guess I
> could order one, but that's about $30 for something I'll never use
> again.
>
> Construction is going very good...... As soon as I can decide what to
> do about the plug/lid I'll weld the top on it and try out "da bomb"
>
> Oh, 4 pounds of dry ice keeps only 2 days inside an Igloo cooler inside
> your freezer.

So what altitude do you calculate your rocket will achieve after the plug
strips from the pressure? You'll have to subtract the energy loss due to
the cylinder ripping through your wall first, though. :)

dwhite <--- still following this post!

[Chameleon]

"Morten" > wrote in message
...
>
> "Elaine T" > wrote in message
> m...
>>
>> >
>> HCl fumes badly in concentrated form, and I think I remember some fumes
>> from dilute HCl (haven't handled the stuff in a while). Same with
>> acetic acid for that matter. Wouldn't you tend to acidify the fishtank
>> some with acid fumes, or are they not concentrated enough to matter?
>
> HCl does indeed fume a bit and so does the Acetic Acid (Vinegar), but the
> acid is inside the ballon / drip bag inside the first container, and the
> only way out of there is via ahose leading to the main reactor where it
> gets
> neutralized / reacts with the baking powder and because you only draw off
> the gas you should be fine. If you're to worried you could send the CO2
> gas
> through a bubble counter / water scrubber, that will take care of any
> stray
> HCl / Acetic Acid molecules that might be in gas form inside the main
> reactor.
>
> So in fact there will be 4 containers, one which is open at the top with
> water in it with a hose comming out of the bottom, the hose leads to the
> acid in ballon container on the outside of the ballon, the hose from the
> ballon goes through the bottom of the acid container and leads to the main
> reactor which also contains the baking powder solution. From the main
> reactor a small hose goes through a smaller container filled 2/3 with
> water
> so that the co2 has to bubble through the water and out via another hose
> above the water level and into tank diffuser / co2 reactor / valve /
> whatever...
>
Or you could bubble through a concentrated solution of NaOH which does not
fume and would last a lot longer than a pure water bubbler. A flask full of
NaOH pellets backed by some MgSO4 pebbles (to remove moisture from the gas
before it contacted the NaOH, which is hygroscopic) would also work.

[spiral_72]

Well, good news...... I found a 1"-40 tap and die to make a plug in the
top of my cylinder. A 1 inch hole isn't exactly what I had in mind, but
it'll have to work for now. I will start with some solid bar stock for
the plug if I can find it..... Chances are I'll have to turn it on the
lathe before the die will accept it.

That's what I'll be doing over lunch today. Probably won't finish
today. I still don't know what pressure this thing will balance out
at..... I couldn't find any information on that. It seems to me the
1200psi would be complete "theoretical" sublimation. I have also
considered, once pressure inside the tank builds, temp should change.
The CO2 will absorb heat? right? I would guess the sublimation rate
will be dependant on the thermal properties of the tank......The tank
will get cold, right?

[spiral_72]

Um, that's "solid roll stock" - Good grief !

[Elaine T]

spiral_72 wrote:
> Well, good news...... I found a 1"-40 tap and die to make a plug in the
> top of my cylinder. A 1 inch hole isn't exactly what I had in mind, but
> it'll have to work for now. I will start with some solid bar stock for
> the plug if I can find it..... Chances are I'll have to turn it on the
> lathe before the die will accept it.
>
> That's what I'll be doing over lunch today. Probably won't finish
> today. I still don't know what pressure this thing will balance out
> at..... I couldn't find any information on that. It seems to me the
> 1200psi would be complete "theoretical" sublimation. I have also
> considered, once pressure inside the tank builds, temp should change.
> The CO2 will absorb heat? right? I would guess the sublimation rate
> will be dependant on the thermal properties of the tank......The tank
> will get cold, right?
>
Anything uninsulated that I've ever put dry ice in has gotten quite cold
and had condensation all over the outside. Plan on a damp cylinder.

--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><

[Dan White]

"spiral_72" > wrote in message
oups.com...
> Well, good news...... I found a 1"-40 tap and die to make a plug in the
> top of my cylinder. A 1 inch hole isn't exactly what I had in mind, but
> it'll have to work for now. I will start with some solid bar stock for
> the plug if I can find it..... Chances are I'll have to turn it on the
> lathe before the die will accept it.
>
> That's what I'll be doing over lunch today. Probably won't finish
> today. I still don't know what pressure this thing will balance out
> at..... I couldn't find any information on that. It seems to me the
> 1200psi would be complete "theoretical" sublimation. I have also
> considered, once pressure inside the tank builds, temp should change.
> The CO2 will absorb heat? right? I would guess the sublimation rate
> will be dependant on the thermal properties of the tank......The tank
> will get cold, right?

I know this is a long shot, but is there any concern about the steel you are
using for your cylinder at the very low temperature dry ice is at? Is
embrittlement or anything else that could weaken the cylinder a concern?

dwhite

[spiral_72]

Actually, yea..... I thought about that. I really don't know what to
expect. I would suppose a material could be brought to a low enough
temp causing that material to become brittle. Water, plastic, chewing
gum, lots of stuff becomes brittle at a low enough temp. Any idea what
that temp is for steel? Oh, a little note here. The dry ice did not
seem to effect my lunch box. I'm still using the lunch box anyhow :)
<pat> - <pat>..........3 hours 30 minutes till eatin' time.

A damp cylinder is the least of my worries. Besides maybe I can collect
it and use the water to refill what evaporates from the tank. HA!

So, many unknowns..... Guess that reaffirms the fact that the
cylinder's first week or two will be spent outside.

[Dan White]

"spiral_72" > wrote in message
oups.com...
> Actually, yea..... I thought about that. I really don't know what to
> expect. I would suppose a material could be brought to a low enough
> temp causing that material to become brittle. Water, plastic, chewing
> gum, lots of stuff becomes brittle at a low enough temp. Any idea what
> that temp is for steel?

I haven't looked that up -- maybe it can be found by googling. It probably
depends on the type of steel, although they might all be in the same
neighborhood. I checked on dry ice the other day and I think it sublimes
at -78.5 deg C at atmospheric pressure, and warmer at higher pressure, but
you'd need an equilibrium diagram for that. -78.5 C should be the worst
case though.

dwhite

[[email protected]]

My odds for this one:

60% chance the whole thing is a hoax. Pretty funny one at that.
25% chance of a fizzing flop due to leaky welds and threads.
14% chance of a new Darwin Award winner
1% chance Spiral will have the last laugh when the whole thing works as
planned.

[spiral_72]

1 LITTLE PERCENT!!!???!!! WHAT'S UP WITH THAT?

Actually, the ONLY thing I am concerned about is I throw the ice in
this dude....cork it..... have it build up pressure and the CO2 only
lasts five minutes. I have no idea what the equivalent gas volume a 1
pound chunk of dry ice has.

[spiral_72]

Oh, for those wanting an update...... Hopefully I will be able to cut
threads today over lunch for the tank pressure gauge. I will hopefully
weld the top on it tonight.and hopefully I will have some news, good or
bad, by Monday morning.


1 percent.... good grief.

[Happy'Cam'per]

"spiral_72" > wrote in message
oups.com...

> 1 percent.... good grief.

ROFLMAO....I certainly wish you luck with it, and try not to blow yourself
and family into the next millenium.
--
"In the beginning, God said the four-dimensional divergence of an
antisymmetric,
second rank tensor equals zero, and there was Light , and it was good."

[Elaine T]

spiral_72 wrote:
> 1 LITTLE PERCENT!!!???!!! WHAT'S UP WITH THAT?
>
> Actually, the ONLY thing I am concerned about is I throw the ice in
> this dude....cork it..... have it build up pressure and the CO2 only
> lasts five minutes. I have no idea what the equivalent gas volume a 1
> pound chunk of dry ice has.
>

Well, the volume depends on the temperature but the ideal gas law lets
you calculate it. (more or less)

pv=nrt
p = pressure in atmosphteres
v = volume in litres
n = number of moles
r = a constant = 0.08205 L atm / (mol·K)
t = temperature in degrees K.

C02 is 44 g/mol and a pound is 454 grams so you have about 10 moles of
C02. At standard temperature and pressure (273K or 0C and 1 atm), one
mole of gas is 22.4 L of volume. So your 1 lb block would sublime to
occupy 231 litres of volume at freezing.

You can use the number of moles, your tank volume, the temps in the
tank, and this equation to predict the actual pressure in your tank in
atmospheres.

--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><

[Dan White]

"Elaine T" > wrote in message
. ..
> spiral_72 wrote:
> > 1 LITTLE PERCENT!!!???!!! WHAT'S UP WITH THAT?
> >
> > Actually, the ONLY thing I am concerned about is I throw the ice in
> > this dude....cork it..... have it build up pressure and the CO2 only
> > lasts five minutes. I have no idea what the equivalent gas volume a 1
> > pound chunk of dry ice has.
> >
>
> Well, the volume depends on the temperature but the ideal gas law lets
> you calculate it. (more or less)
>
> pv=nrt
> p = pressure in atmosphteres
> v = volume in litres
> n = number of moles
> r = a constant = 0.08205 L atm / (mol·K)
> t = temperature in degrees K.
>
> C02 is 44 g/mol and a pound is 454 grams so you have about 10 moles of
> C02. At standard temperature and pressure (273K or 0C and 1 atm), one
> mole of gas is 22.4 L of volume. So your 1 lb block would sublime to
> occupy 231 litres of volume at freezing.
>
> You can use the number of moles, your tank volume, the temps in the
> tank, and this equation to predict the actual pressure in your tank in
> atmospheres.

....and you've already provided the volume and pressure, so he can just solve
for the new pressure after finding out his cylinder volume. P1V1 = P2V2 as
you know, so

(1 atm)(231 litres) = P2(cylinder volume). This is the pressure at 0C.
Spiral - just divide each side by the temperature (T1 = 273 and T2 = room
temp or whatever you want) and solve for P2 if you want to know your
pressure at different temperatures. You might need to look at a property
diagram for CO2 to make sure your results are correct. If you calculate
your pressures to be too high, for example, you might be getting a phase
change in reality.

dwhite

[Dan White]

"spiral_72" > wrote in message
oups.com...
> Oh, for those wanting an update...... Hopefully I will be able to cut
> threads today over lunch for the tank pressure gauge. I will hopefully
> weld the top on it tonight.and hopefully I will have some news, good or
> bad, by Monday morning.
>
>
> 1 percent.... good grief.
>

Hey, I thought 25% chance of leaky welds was an insult! You obviously do
something like this for a living, so I have to think you will make good
welds and threads. But then again, you might be a troll! :)

dwhite

[Joe Crowder]

"Dan White" > wrote in message
...
> "spiral_72" > wrote in message
> oups.com...
> > Actually, yea..... I thought about that. I really don't know what to
> > expect. I would suppose a material could be brought to a low enough
> > temp causing that material to become brittle. Water, plastic, chewing
> > gum, lots of stuff becomes brittle at a low enough temp. Any idea what
> > that temp is for steel?
>
> I haven't looked that up -- maybe it can be found by googling. It
probably
> depends on the type of steel, although they might all be in the same
> neighborhood. I checked on dry ice the other day and I think it sublimes
> at -78.5 deg C at atmospheric pressure, and warmer at higher pressure, but
> you'd need an equilibrium diagram for that. -78.5 C should be the worst
> case though.
>
> dwhite
>

Dodge the whole embrittlement problem by putting down a layer of 1/4" - 1"
thick styrofoam between the dry-ice and the base of the tank. It should not
affect the volume capacity significantly, but it will keep the steel at a
reasonable temperature. It will slow down your melt rate quite a bit, but
that's probably not a bad thing anyways.

You could use a ceramic or hard plastic insulator too, but I'd be concerned
about the additional shrapnel when the tank explodes ;-)

Joe

[spiral_72]

Hey, I cut a nice plug for the top yesterday. I ended up with one inch
of 1"-40 threads on a 1.25" dia plug. I bored a 1/8" hole through the
plug, down the centerline. Finally I bored a 7/16" - 1" deep hole and
cut threads for 1/4" pipe. I mounted my pressure gauge in the top of
the plug.

All I can find at the moment is a 0-60bar gauge... 800 something psi I
think. It is actually a borrowed gauge, that's why I mounted it in the
plug. I figured that's better than trying to fix a big gaping hole in
the tank when a new gauge requires an assortment of fittings to thread
1/4" pipe. The fitting on this gauge is brass instead of steel. I don't
gat any warm fuzzies from that, but I guess we'll see. After all I am
testing Da Bomb outside right?

The neighbors have goats..... I wonder how goats respond to 1/4" steel
debris traveling at the speed of sound? and a shock wave?

"Da Bomb" = "Da Goat Bomb"

[Elaine T]

spiral_72 wrote:

> The neighbors have goats..... I wonder how goats respond to 1/4" steel
> debris traveling at the speed of sound? and a shock wave?
>
> "Da Bomb" = "Da Goat Bomb"
>
I have a sudden very odd mental picture of goats in flak jackets!

--
__ Elaine T __
><__'> http://eethomp.com/fish.html <'__><

[spiral_72]

IT WORKS!!! IT WORKS!!! IT WORKS!!!

AHA! o.k....... the news.

Things didn't start out well at all. I cross threaded my plug (I have
no idea how) and at 40 threads per inch..... they were pretty much
immediately wasted, which means the top of the tank was wasted,
cause'it's welded in. In an effort to ward off defeat I welded the plug
in the top of the tank. Hey, I had to make a new one anyways, right?

Next problem was, how the heck am I supposed to get the dry ice in the
tank? Anyways to make a long story short....
I put about 1/2 a pound of dry ice and about 1/4 cup of water in a hole
for 3/8"pipe and put the regulator back on, closed the bleed valve and
closed the regulator. it took about 60 seconds to steadily build 60psi
at which point I found a leak. In my hurry I forgot to put teflon tape
back on the regulator pipe (where I inserted the ice). CRAP!
I had to leave, The previous problems took too long. I was already 10
minutes later for an appointment. I dropped everything and left.
Hopefully tomorrow I can start the tank repair.

I will note that 1/2 pound of dry ice sublimates into A LOT of
volume... I actually bled off all the pressure at one point and closed
the valve again. The pressure built back steadily to around 60psi and
held. Very cool stuff.... I can't wait to fix my tank. I wish I knew a
better way to cap the thing. Any ideas? Remember, it could be about
1200psi we are talking about.