# Freezing a new CO2 tank before initial use ?



## Peter16 (Jan 12, 2009)

Are you supposed to freeze a brand new co2 tank before you fill it up for the first time?
I have been told to, but was not sure if anyone else does it, and how it benefits the tank ?

Peter


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## Dielectric (Oct 7, 2008)

i never heard of doing that. i didnt do it to mine. it gets pretty cold after you fill it anyways.


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## Peter16 (Jan 12, 2009)

Does this sound like a plausable concept?

"When tranfering liquid co2 from a donor bottle to your cylinder the donor bottle is siphoning liquid co2 which is always attemting to trafer in a gas. The thing that helps prevent this is temp. The colder the bottle the more liquid co2 it will accept. So basically to ensure you get a full fill your bottle should be as cold as possible."


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## jmhart (Nov 13, 2007)

Not necessary


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## intothenew (Aug 1, 2008)

As long as you are buying by weight, it should not matter.


"As long as there is liquid in the tank, the pressure in a CO2 tank is determined ONLY by the temperature. At room temperature (70 degrees F) its about 853 psi."



I think your cooling thought comes from an old Indian trick in the paintball circles.


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## Peter16 (Jan 12, 2009)

well guess what !

went to the aquarium to get it filled.
1st thing the guy said was, next time freeze it before hand and i will be able to put almost double the amount in.


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## intothenew (Aug 1, 2008)

Be really careful about the possibility of getting liquid into your regulator, they go south after that.


Weigh the tank under each circumstance, I'm curious as to the actual gain from this.


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## Peter16 (Jan 12, 2009)

Wouldnt you take the regulator off before freezing it ?


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## intothenew (Aug 1, 2008)

Yes, but an "over full" bottle could present the possibility of liquid CO2 entering the regulator rather than gas. Same issue applies for not turning the bottle on its side while in operation.


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## Tex Gal (Nov 1, 2007)

I asked the guys at the welding shop about this. They said they had never heard of it. They said it doesn't make sense.

I began to think that the CO2 is liquid and is very COLD. As it hits my tank the tank begins to get VERY cold. When I get my little paint ball tank back it feels cold. It only tanks a matter of minutes for them to fill the paint ball tank. SO... when the CO2 hits the metal it will automatically freeze the tank if it stays a liquid. It can freeze the tank much quicker and efficiently than anything I can do. Doesn't it make sense that this happens when it's filled anyway? ... just my rambling thoughts....


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## hooha (Apr 21, 2005)

Are we talking paintball cannisters or the larger CO2 containers?

If it's the latter then I would be concerned that an aquarium shop is filling them "to hold double what it's supposed to carry in on of the larger tanks. As others mentioned before, it should be sold by weight in those circumstances.

If it's a paintball cannister, I'd still be a little bit wary about trying to overfill it.....like others mentioned you can run into problems if liquid CO2 starts going into your regulator....


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## jmhart (Nov 13, 2007)

yeah, if he said that, then he either doesn't know what he's talking about or he's cheating you.

5# of co2 is 5# no matter what the temp.


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## Minsc (May 7, 2006)

I have read many a story of people having their tanks overfilled. When the CO2 warms, it increased in preasure and can blow the tanks pressure relief valve. Depending on the type of valve, it can completely empty the tank, or close again once the correct pressure is reached. At any rate, you will have a dry cleaning bill for your pants


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## Valthenya (Feb 11, 2009)

my husband used to weld and he's never heard of this


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## The old man (Apr 12, 2008)

I've heard you get more by having a tank cooled before filling. Also you should not put a regulator back on until the tank is at room temperature.


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## Peter16 (Jan 12, 2009)

Pretty sure it only applies to smaller tanks, paint ball sized.

I guess if its cooler then more liquid can fit in before it turns into a gas due to tank temp?

Well i dont know, I was just told this by 2 different people, so must have some validity behind it.


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## JET (Dec 20, 2008)

I believe CO2 has an ambient temperature of -109 F, that would make freezing the tank in anything a normal person would have access to would have no effect, I think.


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## jmhart (Nov 13, 2007)

Again, weight is weight...5# is what you get.


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## BryceM (Nov 6, 2005)

From a scientific point of view, you should get 5 pounds of CO2. There is a tare weight stamped on each cylinder and the person filling it should keep filling until there is 5 lb inside.

The temperature of the CO2 in the cylinder will start off identical to the temperature of the surrounding environment. When CO2 transitions from liquid to gas (vaporizes), energy is required and the temperature will drop. When CO2 is converted from gas to liquid (using a compressor), energy is added and the temperature will rise. This process explains how an air-conditioner works.

The pressure inside a CO2 tank will depend on a few things. I initially thought it only depended on the temperature, but like so many other things, it's a bit more complex than that:


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## bsmith (Dec 13, 2006)

That guy was crazy, This is how myths in the aquatic community get started. 

"Cu is the last ingredient in the food I just fed my shrimp, OH NOOOOO"

"Excess Nitrate causes algea"

On and on it goes.

Dont freeze your tank. 

OR better yet weigh it after its filled frozen and not frozen and be the judge yourself.


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## TNguyen (Mar 20, 2005)

Myth? Ha! I just went to an industrial plant to have my tank refill and they freeze it. Industry standard is they won't fill to capacity due to the reason for leaving room for gas expansion. You still get more than going to places that do tank to tank refill. Those setup are more design for paintball system.


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## bsmith (Dec 13, 2006)

Say you live 5 minutes from the filler. If you put it in your freezer (roughly 0 deg F) by the time you get there it will be practically thawed...

BTW, I just called my local Airgas and asked them this question. They said they do not freeze or cool any of the containers they fill.


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## Seattle_Aquarist (Mar 7, 2008)

Hi All,

I look at it this way, I have a 5# tank. I weigh it before I leave, I weigh it when I get back. It should weigh 5# more after filling. If I pay for 5# I should get 5#.......


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## ray-the-pilot (May 14, 2008)

Peter16 said:


> Are you supposed to freeze a brand new co2 tank before you fill it up for the first time?
> I have been told to, but was not sure if anyone else does it, and how it benefits the tank ?
> 
> Peter


Well, I don't know how they fill my CO2 tank (next time I get it filled, I'll ask to see). 
I've seen them fill my propane tank any number of times. They open it to make sure it's empty then connect it to their tank. They put the tank on a balance and zero out the weight. Then they put on a 25# counter weight. They fill the tank until the balance returns to zero. 25# exactly.

I don't know what freezing my tank will accomplish since I get 25 # no matter what.

When I bring a new propane tank they usually open the vent more to remove the air from the tank. I still get 25# but they loose a little; so, maybe by freezing your tank you save the supplier a little money.


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## Peter16 (Jan 12, 2009)

It says on the bottle ID card
"freeze cylinder before filling"

Like i said before, I think it only applies to smaller bottles. 

It also says, when filling do not exceed 66% of the cylinders total water capacity.


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