Do I want a CO2 Tank?

The first thing we should do is explain why there are different gasses and tanks used in paintball… Paintball was traditionally powered by CO2 which is Carbon dioxide. That was because it was easy and cheap to buy CO2 Cartridges. They would come in various sizes, and you would just buy a bunch and go shoot. When you used up a cartridge, you’d throw it away and screw in another. These little cartridges were good for anywhere between 20 and 100 shots depending on the gun and the cartridge size.

Well, with the advent of paintball guns that would put out 20 balls a second, instead of shooting 20 in an hour.. these small self contained cartridges became pretty much obsolete. You will still find them used for small pistols.. but not much else.

So paintball guns were set up to take larger CO2 tanks, like the 9oz Tank, all the way up to 20oz Tanks. The great thing about these tanks, is they could be refilled off a big CO2 tank by simply using a CO2 Fill Station. This meant if a guy wanted to start up a paintball field, he could just call up one of the gas companies, and get some tanks of CO2 delivered, get one of the fill stations.. and bingo! He was filling paintball tanks and it cost him under a couple hundred bucks!

CO2 Temp/PSI
Temp F Pressure
35 528.14
40 567.58
45 609.16
50 652.99
55 699.15
60 747.75
65 798.93
70 852.82
75 909.62
80 969.57
85 1033.1

So why have we moved away from CO2?? Carbon Dioxide is a liquid under pressure. That’s why it’s safe and easy for the tanks to be delivered to a paintball field. We are not dealing with very high pressures. The pressure is basically generated as the CO2 goes through a state change from a liquid to a gas.

So you’re holding a CO2 bottle, and you can feel the liquid sloshing in it. You put it on your gun and when you shoot, it is the gas that is supposed to be shooting your paint ball. As the gas is used, the pressure in the paintball tank drops slightly, and more liquid vaporizes back into a gas. This happens over and over every time you shoot. It’s good in theory, but there can be some problems.

You’re running and shooting, moving the gun up, down, back, forth, and as you’re shooting, you may not always be getting pure gas. Some of the liquid CO2 may escape into the system as well. Then some expansion can happen in the gun, behind the bolt, which then will change the pressure. This makes for inconsistent shooting. With CO2, depending on how fast, what position the gun is in, etc, you might have a ball leave with a velocity of 280, then 300, then 260. This can cause your paint to either over shoot, or undershoot your target. Additionally, if you’re really ripping, you can get the liquid CO2 hitting the O-rings in your gun and the cold liquid will shorten their life allot! To help with this, you can add an Expansion Chamber. This gives the CO2 a place to make sure it is fully expanded into a gas before it enters the firing mechanism.

Even with the best setup, expansion chambers, etc, there is still variation in shooting, and that can also greatly be affected by outside temperature. Check out the chart at the right and you can see that even a little temp change throughout the day, or in the bottle can have a huge effect on your gun and thus the chrono speeds.

Compressed air is much more consistent. It will output the same pressure each shot. It is not affected by temperature like CO2, and overall it is much better for the components in your gun. You may have heard people talking about Nitrogen systems, while the air you are breathing right now is just shy of 80% nitrogen. People in paintball talk nitrogen, because again, it is cheaper to have a gas company deliver nitrogen bottles for filling.

Now that sounds stupid. Nitrogen is cheaper than air?? Actually yea.. because the only compressed air you can buy is extremely purified compressed medical grade breathing air, while nitrogen is used for all kinds of stuff in commercial applications.

The other option is to buy a compressor that can fill your tanks, but unfortunately, you can’t use your standard Home Depot compressor. Those will go to about 125psi, and the tanks need to be filled to 3000 or 4500 psi, and a compressor capable of those pressures runs in the $12,000 range. Fortunately, enough of the better paintball fields realize that today’s players demand the benefits of compressed air, (also known as HPA – high pressure air) so they have taken the steps and expense to install equipment for filling these bottles.

The other good news, is if you don’t have a spare $12,000 kicking around just to fill your bottles, and you play in the woods, or a field that does not have HPA fills, there is another option. You can fill the bottles off a Scuba Tank. Scuba shops are everywhere, and they fill tanks to 3000psi all the time. And filling one of these tanks normally costs about 5 bucks. Then by using a paintball / scuba fill adapter, you can fill your tank in the field from a scuba tank.

The way that works, is when you hook your empty bottle up to a scuba tank containing 3000 psi, then open the valve, the two tanks equalize together, taking some of the air from the scuba tank. Each time you equalize into your paintball tank, you lose about 200 psi from the scuba tank. So your first fill will be about 2800 psi, your second will be about 2600 psi, the third will be about 2400 psi, etc. To really extend your playing with the max pressure, you use 2 scuba tanks.

When using 2 scuba tanks, you will want to mark them as the first fill tank, then the top off tank. This is known as a do it yourself cascade system. This way, you fill off the first tank, and it drops to 2800 psi. But then you top it off with the other tank. But since your paintball bottle already has 2800 psi, it only takes a very little air from the second scuba tank, and your bottle now has about 2980 in it, as does the second scuba tank. Then next time you fill, go to the first tank, you get 2600, then top off with the second and you get about 2950 psi, etc. By adding a third tank, you can go up to about 20 – 25 fills easily.

To see exactly how many you will get, you need to know which size scuba tank, and what the size of your paintball bottle is, then go check out our Paintball / Scuba Tank Fill Calculator.

If you are buying paintball fills, they probably cost you about 3 bucks a piece – so 25 fills would cost you 75 bucks, but with scuba tanks – it would cost you about 15 bucks. Take the other $60 and buy yourself a case of paint! Plus you have the advantage of being able to play in remote areas where fills are not available unless you do it yourself.

Now you will see the HPA bottles cost more than CO2 tanks.. and that is because when using CO2, the gas expands from the liquid at a standard pressure. With Air, you have a regulator built onto the tank – if you tried to run 3000 psi straight into the gun – you’d blow the o-rings apart – but with the regulator built in – it takes care of the pressure and delivers it at a consistent, constant pressure. Also all of the Air bottles have a built in gauge, so you know how much air is left in the bottle. No more having your gun die with no warning, just as you’re trying to mount an attack.

Aluminum tanks are rated for 3000 psi, but if you also play on fields that offer 4500 psi fills, you may want to invest in a 4500psi fiber tank. These come in different sizes, and obviously, the bigger the tank, the more shots. There is a lot of variation in guns, but you should be able to get about 600 – 1000 shots from a 48 inch, 3000 PSI tank while you will get twice that with a 88 Cubic inch at 4500psi. If you have a fiber tank rated for 4500 psi, you can still use a scuba fill system, but it will only fill to 3000 psi, and you’ll end up with about 2/3 the shots – so about 1200 or so.

So which do you want? If you have a Tippman 98, and shooting 200 – 400 balls is a full day for you – you can get by with just CO2. If you’re a serious paintballer, and blow through 400 balls in the first 30 seconds of a tournament – you’re probably going to go with a 4500 psi Air system. And of course, if that bottle is a bit big and bulky for you, you can always strap it on your back and use a Remote System cable.

Shots per Tank
CO2 Size
Shots
12-g
35
3.5-oz
150
7-oz
350
9-oz
425
12-oz
600
14-oz
700
16-oz
800
20-oz
1100
24-oz
1225
26-oz
1300
30-oz
1425
32-oz
1500
36-oz
1625

Here is a table that will give you an approximation of shots with different size CO2 tanks. Again, a lot of variables such as temp, how fast you are shooting, which gun… but it gives you a ball park.

And if you want to use air, here is a formula that will get you close as well:

Take the pressure and divide by 1000. Then
multiple by the number of Cubic inches the tank is. Then multiply by 4.
This will give you a conservative guess on how many shots you can get
with that tank.

Of course if you have a very efficient
gun, you might beat that by 10 – 20%. Let’s do an example.

For a 3000 PSI 47 inch tank – how many shots?? We take 3000 divided by 1000 and that gives us 3. Then 3 times 47 is 141. 141 times 4 is 564. So you should get about 564 balls… maybe up to 100 or so more with a better gun.

Let’s do another: How many shots with a 92 cubic inch 4500 psi
tank?
4500 divided by 1000 is 4.5. 4.5 X 92 is 414. 414 x 4 = 1656 – so you’d get about 1650 shots or so with that bottle and a standard gun. A high efficiency gun, might get you up to 1800 – 2000.


If you are going to use air, I’d highly suggest you get a Dust Cover for the fill nipple, otherwise, when you do a dive in the dirt, and get some sand in there, it will be blown into the tank the next time you fill, then blown into the gun the next time you shoot. This will effectively sand blast the inside of your gun causing damage to the bolt, o-rings, etc.

Hopefully this helps you get the tank and system that will work best for you!