DIY CO2. Can you use a valve to control amount?

[yoink]

Have you tried using two bottles and staggering the refills between the two? I think that and tinkering with the recipe would give you a more consistent co2 content.

[wood]

Originally Posted by yoink

Have you tried using two bottles and staggering the refills between the two? I think that and tinkering with the recipe would give you a more consistent co2 content.

I haven't tried anything as of yet. I think I am going to start with 3 x 2L bottles. One of them being the fermenter (red) and the other two being reservoirs. I will have valves for each bottle (olive) as well as the main valve leading to the tank. I will t-branch both reservoir bottles (green) and use an elbow joint (green) for the fermenter bottle.

[BlueRam]

Originally Posted by wood

Ya see the problem is not the time it takes for the yeast to die off, but instead the amount of wasted CO2. The yeast could die off long before I run out of CO2 if I could figure out how to safely do this. Achieving the least amount of wasted CO2 would really help especially in the long run. Perhaps instead of using (2) 2-Liter coke bottles, why not something stronger? The reason why the bottles burst is because of the plastic. The plastic can't hold up to high pressure. The reason why CO2 canisters are metal.

Hey there Sparky, looks like you have a few ideas mixed up. First of all CO2 canisters are seamless metal because at room temperature CO2 remains a liquid above ~800 psi. Yeast survival is limited in both the % alcohol and CO2 pressure.

Next, DIY is cheap (~$5 to start!) but requires a lot of work. Compressed is expensive (>$150?) but goes for months (or years). The old time or money balance.

The 3 x 2L bottle idea will work as follows: The gas generated in container A with increase the pressure evenly in A, B, and C and eventually generate bubbles in the aquarium. At that point the pressure in the reservoir is stable and each unit of gas produced in A goes directly into the aquarium. No appreciable volume of gas is "stored" (ok, about 4L at 2-10 psi) with the major effect of increasing (>3X) the time for bubbles to start.

So as posted elsewhere, rotate 2 or more bottles for consistency and lean out the yeast/add backing soda to increase the duration of a charge.

[retoid]

anyone know how much pressure diy co2 creates?
in psi?

[BlueRam]

Originally Posted by retoid

anyone know how much pressure diy co2 creates?
in psi?

Given that a working DIY displaces water, and that 1-foot-high column of water exerts 0.44 pounds per square inch (psi) (Howstuffworks "Why can boats made of steel float on water when a bar of steel sinks?") I would refine my guess to <1 psi.

Now who would know much pressure a soda bottle can hold?

"In order to find the failure point of the bottles they hooked up the pneumatic pump from Grant's "Deadblow" battle robot. The soda bottles exploded at 150 psi and the water cooler bottles exploded at 95 psi, so they decided that using soda bottles was better for the test even though they got much more lift out of the water cooler bottle."

Annotated Mythbusters: Episode 42: Steel Toe Amputation, Bottle Rocket Blast Off

Edit: "Documentation" of yeast explosion in glass bottle: Exploding Yeast Bottles!

[retoid]

haha cool! and thanks

[tusk]

I would move the output on the ladder first, cough up the $$$ for a real CO2 second, but....... at your own risk..........

I ran a 2L DIY CO2 with a valve for a while. I then found a different container that was better for many reasons (Basically an insulated 2L thermos. If you've ever used a cryo-cuff, you know what it is). I ran that with a valve. It worked fine...... for my settings...... at my own risk.

[TAF CAF]

Originally Posted by wood

Maybe I am just not understanding the idea here, but how are you going to get the CO2 out of the 'storage' bottles once the pressure is decreased? And where is the air going from the bottles while they fill with CO2?

As far as it looks like, you will pump the same amount of air into your tank as you are doing now, but with the CO2 ammount greatly diluted by the common air in the 'storage' bottles.

[fish_lover0591]

ok i think basically wood wants to produce co2 in bottle #1 then have the co2 equalize their pressure in bottle #2 and #3 and use a needle valve to control the co2 from bottle #3 like a pressurized co2 setup. but he doesn't know how much pressure will be built up. I think wood should setup a blow off valve in bottle #3 just to be safe.

[BlueRam]

Originally Posted by fish_lover0591

ok i think basically wood wants to produce co2 in bottle #1 then have the co2 equalize their pressure in bottle #2 and #3 and use a needle valve to control the co2 from bottle #3 like a pressurized co2 setup. but he doesn't know how much pressure will be built up. I think wood should setup a blow off valve in bottle #3 just to be safe.

Ok, this makes little more sense with this function of the needle valve after 3. After further searching, it appears that Champagne approached 100 PSI during fermentation (aggressive yeast in a sealed container) with is then reduced after disgorging to minimize exploding bottles outside the winery.

Champagne and Sparkling WIne: What it is and How It's Made

Definitely a candidate for "don't try this at home!"

To add something slightly useful: The blow off valve could added by making the 90* on #1 a T link like 2&3 with a quick fail plug.

[Rex Grigg]

Originally Posted by TAF CAF

Maybe I am just not understanding the idea here, but how are you going to get the CO2 out of the 'storage' bottles once the pressure is decreased? And where is the air going from the bottles while they fill with CO2?

As far as it looks like, you will pump the same amount of air into your tank as you are doing now, but with the CO2 ammount greatly diluted by the common air in the 'storage' bottles.

This is correct. Unless you can "pump" the CO2 into the storage bottles under pressure all you are going to end up with is bottles full of CO2 at the same pressure. And until you fill the volume of the bottles with CO2 you will mainly be pumping air into the aquarium.

[vidiots]

This thread really got me thinking, however I can't think of any sort of cheap simple DIY setup that would safely do this.

I was thinking that the only safe way to restrict the flow and cause a back pressure would be to have a pressure relief valve in line to vent the excess pressure buildup somewhere below the danger point. You would also need some sort of low pressure regulator in line after the relief valve and before the needle valve to maintain a constant pressure since your source is inconsistant. Without the regulator your flow of CO2 will still vary some based on the varying pressure behind the needle valve. With the relief valve you would still have excess CO2 going to waste. Unless you used a bottle with a much higher burst pressure rating than the yeast is capable of generating and a relief valve with a much higher rating or none at all since the pressure will always stay below the bottle's & plumbing's burst pressure. I'm sure that at some point brewers have determined the maximum pressure fermentation can generate and selected appropriate sealed containers.

I think that the expense of this, while still maintaining a DIY CO2 source instead of a pressurized system would just get you the worst of both worlds, expense and high maintenance.

If you want to have a more consistant amout of CO2 getting into the tank, you might wanna just try using smaller bottles and more of them swaped out at different times to maintain an average combined output.

[vidiots]

Originally Posted by BlueRam

Given that a working DIY displaces water, and that 1-foot-high column of water exerts 0.44 pounds per square inch (psi) (Howstuffworks "Why can boats made of steel float on water when a bar of steel sinks?") I would refine my guess to <1 psi.

This assumes that there is no restriction to the flow. A restriction to the flow will cause the pressure to be higher behind the restriction. If the water in the tank is the only flow restriction the pressure in the line will balance out with the weight of the water above the output which would work out to about 0.036psi per inch of depth. This also asumes that the tubing itself is large enough so that it doesn't count as a restriction because then the pressure in the bottle would be higher than the pressure in the tubing.

As for how stuff floats, your guess is close but it's more than weight per area, it's weight per volume or density. Boats are hollow meaning low weight per volume because most of the space is filled with much lighter air, they sink when they fill up with heavier water. Pure water has a density of about 0.998 grams per cubic centimeter at room temperature and a density of about 0.99997 near freezing. Anything less dense than water will float, anything more dense than water will sink. Salt water is more dense than Freshwater because it has more disolved heavy materials so it's density may get as high as 1.03 grams per cubic centimeter. Air has a density of about 0.0012 grams per cubic centimeter.

[wood]

OK. The three bottle theory is no good. It is true that the pressure will reach a point where there will just be CO2 sitting in the three bottle without enough pressure to release into the tank.

Here is another option.... What if I were to use another container? A container which could withstand a lot more pressure than a 2L bottle? Suppose there was a container which would withstand the entire output of CO2 without release? Does such a container exist that could of course be used with DIY?

Is it futile to even think that the pressure could be controlled with such a container given the fact that maybe the valve or tubing connection could break due to the high pressure?

I am sure that there has to be a way to have DIY CO2 and be able to control output.

I think that this would be a good subject to invest in.... Let's get the minds together..

-Ryan

[Rex Grigg]

Since DIY can't generate a lot of pressure your idea is pretty much doomed to fail. You would need a very large cubic volume to hold the CO2 under what little pressure you can generate with DIY CO2.