Laying CO2 bottles down

[doug293cz]

The 34% fill is NOT correct. If you understand the chart below, then you will know why it is not correct. At 0°F, the fill level is about 65% and at 70°F it is about 85%.

Brew on

You are reading the chart entirely wrongly............. This is a pressure chart as related to fill level, not the other way around. CO2 is a liquid in the bottle, with a small amount of variable density gas above the liquid. ...

H.W.

Ok, I'll explain how to read the relevant part of the chart. To determine relative fill levels, you need to look at the lower right portion of the chart, which I have cropped below:



As you know, a CO2 tank that is not almost empty, nor overfilled, contains liquid and gas in equilibrium, and the pressure of the gas is strictly a function of temperature (thus the horizontal pressure vs. fill over most of the fill range.)

Now what happens if we force more and more liquid into the tank, thus over-filling it? The fraction of the volume occupied by the liquid increases and the gas volume decreases, but the pressure remains the same (at constant temp.) When enough liquid has been added so that there is no available space for the gas, the pressure starts to increase rapidly. Now the more liquid you add the higher the pressure gets. The discontinuities in the pressure vs % fill curves along the red arc are at the fill level where liquid occupies the entire volume of the cylinder, and there is no space for gas. You can calculate the fractional fill (liquid volume/tank volume) for a particular temp at nominal fill (100% on the x axis) by dividing 100 by the x coordinate of the discontinuity in the curve.

... The fill level does NOT change appreciably...... the pressure of the gas in the bottle above the liquid DOES. It is utterly absurd to suggest that the liquid volume changes that radically with temperature. You have your thermodynamics backward here. The 35% figure looks quite close based on the chart you gave.

H.W.

Actually the density (and thus the fill level) of liquid CO2 does vary considerably with temperature. See my previous post for the data (and reference.)

Brew on

 

[doug293cz]

Hmmmm.......

That dip tube ain't worth a damn once it approaches 1/2 full!

If I was an analytical type, I'd say that change in density on the X-Ray @ the top of the cylinder, is the change in density of the metal of the cylinder, when the top or "crown " is formed.

Looks to be a pronounced "concavity" in the middle of that "liquid line" to me.

Not tryin' to stir up any $hit, that's just my take on the X-Ray image..........

It's not a dip tube, but rather an "anti-dip" tube. Because of the rotation of the tank in this x-ray, the tip of the tube doesn't look like it gets close to the side of the tank. The other x-rays at the link show the tube better. If the tank is horizontal, the tip of the tube will be above the liquid level, so no liquid will come out the valve. The anti-dip tubes don't work perfectly because if the tank is tilted off horizontal, it can still pick up liquid depending on the fill level. Liquid sloshing is also an issue.

I am an analytical type, and have looked at hundreds of wide field x-rays during my career. The curvature of the liquid line is due to distortion in the x-ray optics. If the line were due to metal thickness variations at the crown of the tank, then it wouldn't stay horizontal as the tank is tilted. Again, look at the other x-rays at the link.

Brew on

 

[Stealthcruiser]

So, what career field are you in, with lookin' @ wide field X-rays..........N D T ?

 

[doug293cz]

So, what career field are you in, with lookin' @ wide field X-rays..........N D T ?

Circuit boards (until I retired). Lots of x-rays to look inside of multilayer boards for construction and failure analysis.

Brew on

 

[Engenia]

Very old thread I know, but I found it when I was researching this very thing.

Can I use my CO2 cylinder horizontal?​

I've been doing it for years, well before this thread was started, without any problems whatsoever, but why haven't I had any problems?
Here's why.
My tank holds 6 kg of CO2. At 10C the density of CO2 liquid is 0.85 kg/litre, so the volume of CO2 liquid is 6/0.85 = 7.1 litres
The tank is 160 mm OD, so with say 5 mm wall thickness, the ID is ~ 150 mm.
The tank height to the neck is 560 mm. These tank dimensions are only a rough estimate but good enough for this calculation.
Here I use a calculator (https://www.handymath.com/cgi-bin/circlehei4.cgi) to find the height of liquid in a horizontal cylinder
Plugging in the dimensions in metres comes up with a liquid height of 101 mm and a maximum volume of 9.9 litres, which is about right for a back of an envelope check.
So, the liquid height above the bottle centre line is 101 - 75 = 26 mm
The edge of my first regulator (I have 2 in series on the high pressure line) is 95 mm from the centre line of the cylinder, so,

IF I POSITION the regulators VERTICALLY​

(and that is the crux of the matter!) the nearest regulator is 95 - 26 = 69 mm ABOVE the CO2 liquid level

No liquid CO2 can enter my regulator.

Even if the tank were completely full of liquid CO2, the level would be 95 - 75 = 20 mm above the liquid level, but that can not happen unless the filling station is grossly negligent. They would be dicing with death to put that much in the tank.

Whatever you do, DON'T mount the regulator horizontally!

 

[Dr_Jeff]

At around 85F CO2 exhibits a state called supercritical........ Gas and liquid are indistinguishable rather than being two distinct phases. That means that using a bottle in a room where the temp is 85 or more, you are not getting just gas at the regulator, but supercritical fluid. This doesn't apply to laying a bottle down in the fridge of course. Supercritical CO2 is what is used to extract oils from hops..... interestingly enough.

My kegerator sat in the garage in Alabama(it gets hot here) with the CO2 bottle outside of the kegerator for years.

I kept another tank in the other garage where I brewed and fermented and used it to transfer the beer for years.

I still live in Alabama and have a CO2 bottle in the brew shed that I use to transfer beer from the fermenter to kegs, with now ill effects.

BTW- it gets a whole lot hotter than 85.

 

[doug293cz]

My kegerator sat in the garage in Alabama(it gets hot here) with the CO2 bottle outside of the kegerator for years.

I kept another tank in the other garage where I brewed and fermented and used it to transfer the beer for years.

I still live in Alabama and have a CO2 bottle in the brew shed that I use to transfer beer from the fermenter to kegs, with now ill effects.

BTW- it gets a whole lot hotter than 85.

You shouldn't have to worry about a CO2 bottle blowout unless the tank temp gets above 130°F. Check the chart below.

Brew on

 

[Dr_Jeff]

You shouldn't have to worry about a CO2 bottle blowout unless the tank temp gets above 130°F. Check the chart below.

View attachment 770872

Brew on

I suspect it might take more that 130 degrees.

One ALabama summer day at lunch, I took six bottles and got them swapped and left them in the car (closed car in the parking lot, no shade) for the rest of the day, all was fine.

 

[doug293cz]

I suspect it might take more that 130 degrees.

One ALabama summer day at lunch, I took six bottles and got them swapped and left them in the car (closed car in the parking lot, no shade) for the rest of the day, all was fine.

You may have just been lucky. Did you actually measure the temp in the car? Also, if the fill level is lower than rated capacity, then the tank has to get warmer in order for the pressure to exceed 2200 psi. The few times I weighed "full" tanks after swapping, they were not completely full. I have heard this is fairly common.

Brew on

 

[Dr_Jeff]

You may have just been lucky. Did you actually measure the temp in the car? Also, if the fill level is lower than rated capacity, then the tank has to get warmer in order for the pressure to exceed 2200 psi. The few times I weighed "full" tanks after swapping, they were not completely full. I have heard this is fairly common.

Brew on

No, I did not measure the temperature in the car, although, it was a hot summer day, likely near 100 degrees, and the car has a black interior. I don't use one of the front window shades, one mitigating factor could be that all of the side and rear windows have dark tint on them.