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Discussion Starter · #1 ·
I know for a 5 pounder that when full, the tank pressure gauge should read about 800psi and at about 500psi, it’s time for a refill. What about a 24oz paintball canister? Are the numbers the same? My initial pressure was about 700psi. Can I go lower than 500psi before a refill? (I have a pretty good dual stage reg)
 

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My 24 oz I just sold was reading 900 full. Im not sure if it was overfilled but I had to shipped it out to new seller and he requested the tank to be empty and it took about 3hrs with needle valve open to drop to around 200 psi and it was still releasing c02.
 

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I dont believe the size of the canister matters. The gas is being compressed and the container is full when in the 800 psi range (give or take a bit). Doesn't matter if its a 24 ounce canister, 20 pound canister or a 100 pound canister. Once enough gas is crammed into the container to register 800 pounds of pressure its considered full. The problem is sensing the pressure decrease as that doesn't really register on the gauge until the majority of the compressed gas part is gone and you're left with liquid. To avoid end of tank dump with a single stage regulator its recommended to refill at 500 or so psi as once you see that decrease in pressure just a tiny bit you're getting close to the end....and then suddenly its the end. But if you truly have a good dual stage regulator that shouldn't be an issue no matter what size container you're using.
 

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I dont believe the size of the canister matters. The gas is being compressed and the container is full when in the 800 psi range (give or take a bit). Doesn't matter if its a 24 ounce canister, 20 pound canister or a 100 pound canister. Once enough gas is crammed into the container to register 800 pounds of pressure its considered full. The problem is sensing the pressure decrease as that doesn't really register on the gauge until the majority of the compressed gas part is gone and you're left with liquid. To avoid end of tank dump with a single stage regulator its recommended to refill at 500 or so psi as once you see that decrease in pressure just a tiny bit you're getting close to the end....and then suddenly its the end. But if you truly have a good dual stage regulator that shouldn't be an issue no matter what size container you're using.
This is all correct, except the part in bold. CO2 is filled by weight.
 

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Discussion Starter · #5 ·
Thanks for your help. I totally get the high pressure being 800psi regardless of tank size. But, I am a little confused about the rest, especially the part I put in red.

“The problem is sensing the pressure decrease as that doesn't really register on the gauge until the majority of the compressed gas part is gone and you're left with liquid. To avoid end of tank dump with a single stage regulator its recommended to refill at 500 or so psi as once you see that decrease in pressure just a tiny bit you're getting close to the end....and then suddenly its the end.”


This is my first c02 rig and I am just about to set it up. So, you are saying that you don’t see a “gradual” drop over time from 800 to 500psi? The drop is sudden? And then a sudden drop again? When you say a “tiny bit”, are you referring to a second drop in pressure? If so, what would ranges be?
 

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Once enough gas is crammed into the container to register 800 pounds of pressure its considered full. The problem is sensing the pressure decrease as that doesn't really register on the gauge until the majority of the compressed gas part is gone and you're left with liquid.
This is all wrong.

CO2 gas at a certain pressure and temperature condenses to liquid. A cylinder is not considered full dependent on pressure, it could have 800 psi when only 10% filled. It is filled based on weight.

When using the cylinder on your aquarium the liquid slowly evaporates into gas and the pressure in the cylinder remains constant until all of the liquid has evaporated and only gas is left. When only gas is left, the pressure drops and a single stage regulator works differently possibly increasing flow.


A paintball canister will have the same gauge pressure as a 10# cylinder if both contain a sufficient liquid component and both are held at the same temperature.

The above is not true for gas cylinders containing nitrogen, oxygen, HPA etc.
 

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Discussion Starter · #7 ·
When using the cylinder on your aquarium the liquid slowly evaporates into gas and the pressure in the cylinder remains constant until all of the liquid has evaporated and only gas is left. When only gas is left, the pressure drops

So is this why the drop in pressure is not gradual? Is 500psi the point at which the canister consists of mostly gas? If this is the case, does the typical 800-500psi standard apply to all tank sizes?
 

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When using the cylinder on your aquarium the liquid slowly evaporates into gas and the pressure in the cylinder remains constant until all of the liquid has evaporated and only gas is left. When only gas is left, the pressure drops

So is this why the drop in pressure is not gradual? Is 500psi the point at which the canister consists of mostly gas? If this is the case, does the typical 800-500psi standard apply to all tank sizes?
Yes. Unlike an HPA tank or N2 tank the pressure is constant at constant temperature until the liquid has all evaporated.

What paintball regulator do you have? Also if it is dual stage I wouldn't worry about it. As paintball tanks are cheap just have a spare full one. If you have an accurate scale you can just weigh it to determine how much is left in it.
 

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Discussion Starter · #9 ·
I have an AlanLe build. It’s a Linde Union Carbide dual stage with a SS Burkert solenoid and a SS Swagelok M series needle valve. I have an Aquatek cga320-to-paintball adapter with a 24oz Empire paintball canister.
 
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