# co2 tank on it's side



## hornman (Jul 3, 2005)

My cylinder will not fit under my stand. Do you have to keep these upright to work properly or shall I trade my 20 lb for a 5 lb? Sorry for the dumb question. CO2 newbe here.


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## JeffyFunk (Apr 6, 2006)

hornman said:


> My cylinder will not fit under my stand. Do you have to keep these upright to work properly or shall I trade my 20 lb for a 5 lb? Sorry for the dumb question. CO2 newbe here.


CO2 tanks (and all gas cylinders for that matter) must be place upright in order to function properly. Under high pressure, the majority of the CO2 in the tank will be in the form of a liquid on the bottom and a gas on the top. As such, the tank is designed to deliver the gas from the top of the tank. If the tank is placed on it's side, then the tank would probably deliver CO2 liquid (which is not really what you want).

Also, this explains why the tank pressure on CO2 tanks drop very rapidly when they are depleted. When there is a significant quantity of CO2 in the tank, the CO2 will exist in an equilibrium between a liquid phase and the gas phase, keeping the pressure of the tank constant. When the CO2 tank is almost depleted, there will no longer be any liquid phase present in the tank and the CO2 tank pressure will drop quickly.

Therefore, (1) when the pressure of the tank starts to drop, you're going to need to refill the tank pretty soon and (2) it's not that much of a gas savings from filling up the tank when it's below 400 psi than when it's empty (and in fact, you shouldn't run a tank dry).


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## hornman (Jul 3, 2005)

That's not what I was hoping to hear. Thanks for the info!


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## barakainus (Jun 11, 2009)

As Jeffy said, not a good idea. What would probably happen is that the liquid would flow into your regulator and freeze it! It's pretty with all the frost covering it but it doesn't work with chunk of ice inside 
It happens occasionaly in my lab even in upright tanks when they're new and CO2 is drown out fast, the liquid boils and get into the tubes. Everything freezes!


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## Left C (Jun 14, 2005)

Could you hide your CO2 cylinder somewhere and run some tubing from it to the aquarium?


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## fishyfish (Jan 18, 2010)

member "nowmed" has his co2 tank on it's side in his "first tank" journal. http://www.aquaticplantcentral.com/forumapc/journals/69886-first-tank-journal.htmlfirst he had it filled only to 1/4 full so the liquid co2 wouldn't make it's way into the line. then I believe he followed this mod from a jeep forum where they use co2 to fill their tires, their concern is the same as ours. 
http://www.jeepforum.com/forum/f9/how-use-your-co2-tank-laying-down-standing-up-840504/


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## Scotty (Jun 11, 2009)

That mod from the jeep forum would work great.. Just make sure the pipe is always pointing up...


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