Compressed Air vs. CO2 for Paintball

One of the most common questions that we are asked at is the difference between using Compressed Air (HPA) and CO2 tanks. In a nutshell, both provide pressure for a paintball marker to cycle and propel the paintball. However, both work on a different principle and sometimes only one can be used.

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Carbon Dioxide, or CO2, was the first propellant used in paintball and set the standard for many years. For paintball purposes we use it in two types of vessels, refillable CO2 Tanks, and 12 Gram Cartridges, which are used in paintball pistols such as the Tiberius and TiPXm, as well as on stockclass pump markers like the Phantom. These are filled with liquid CO2 which expands to create the pressure used for the marker. This pressure fluctuates due to elevation, temperature and other variables but the benchmark is 850 psi or Pounds per Square Inch.

Using CO2 has some positive advantages. The tanks tend to be smaller and lighter than HPA while yielding the same number of shots or more per fill. Facilities to have the tanks filled are generally easier to find as many gas, welding supply and fire extinguisher shops have the means to fill your tanks, in addition to paintball pro shops. The number one reason for CO2's enduring popularity is cost. CO2 tanks are very cheap so a player can easily own several tanks, thus having plenty of air for a full day of fun.

CO2 does have its drawbacks. Since CO2 is transitioning from a liquid state to a gas, it cools as it expands. This isn't a big deal if you aren't shooting much, but becomes very noticeable when shooting rapidly or a lot. When this happens, the pressure fluctuates from high to low, and your marker's performance and accuracy will begin to suffer. As the tank chills it begins drawing liquid CO2 up into the marker, resulting in pressure spikes that can push velocities to unsafe speeds. If you see big white clouds of vapor coming out the muzzle and white snow falling out the barrel (it's actually dry ice) when shooting you can bet that liquid CO2 worked its way into the marker. And in cold weather, the pressure can get so low with CO2 that many paintball markers won't cycle properly. CO2 tanks also can't be partially filled- you have to empty them out all the way to fill them back up, so no topping off between matches.

Liquid CO2 is also hard on the seals of your marker and can cause damage if it works it way into the solenoids of many electropneumatic markers. Thus many markers cannot use CO2. Always refer to your marker's owners manual to know whether your marker will work with CO2, and if you're still not sure you can call our experts at 800-875-4547.

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Does messing with CO2 sound frustrating? It can be. That's why players started using HPA/Compressed Air, sometimes also referred to as Nitro, Nitrogen, N2, or High Pressure Air. Originally pure nitrogen was used, which explains why some players still refer to them to as N2, Nitro or Nitrogen Tanks. Rather than filling the tank with liquid, HPA tanks are instead pressurized up to the tank's rating of 3000psi or 4500psi. The pressure is then regulated through the tank's regulator down to 850psi (High Output) or 450psi (Low Output).

The beauty of HPA is that the pressure is much more stable than CO2 and changes due to shooting fast or playing in cold weather are barely noticeable. That means no thick clouds or snow from the barrel, no more layers of frost on the marker body and your accuracy improves due to more consistent velocity. Today's electropneumatic markers were designed with these tanks in mind. And since HPA tanks are filled through a nipple at the base of the regulator, they can be topped off between games. That means no matter how long a match goes, you'll be ready for it.

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Compressed Air tanks come in two varieties, aluminum and fiber wrapped. Aluminum HPA tanks are rated up to a maximum of 3000psi. They are smaller and more cost effective, but weigh much more than fiber wrapped tanks. Fiber wrap tanks are rated from 3000psi to 4500psi (consult your tank's label), cost more and have more bulk, but are a lot lighter than aluminum tanks.

The main advantage to 4500psi fiber wrap tanks is that they can handle more pressure and thus yield more shots per fill. Shot counts vary between markers but most get about 10 shots per cubic inch at 3000psi and 15 shots per cubic inch at 4500psi. As an example, the 48ci tank above and to the left can get about 480 shots on one fill. The 68ci tank to the right can get around 1020 shots on a single fill, more than double the yield of the smaller tank.

HPA does have its own set of drawbacks. Facilities for filling an HPA tank are more specialized, and therefore less common. In some remote areas, getting tanks filled can be a problem, and tire pumps and shop compressors do not work, since they rarely go over 180psi. HPA tanks also tend to be a bit larger and bulkier compared to CO2, and you're likely to get fewer shots out of similar-sized tank. Lastly, Compressed Air tanks do cost considerably more than CO2 tanks, and between their bulk and cost, most players don't consider carrying a spare tank.

Depending on the kind of paintball player you want to be, both pressure systems can be attractive. Over the long run, HPA is likely the better investment, since it's easier on the gun's internals, and offers smoother performance. And an HPA tank is a piece of equipment that can transfer to any marker you upgrade to, if you decide to trade in your Tippmann for a Dye. Determine what your needs are for your equipment, and the level of play and style of play you want, and choose accordingly. Or you can call us, and we'll help you figure out what gear is right for you.

Differences between CO2 and HPA

CostLowMid to High
DependabilityImpacted by WeatherStable
Refill AvailabilityWidely AvailableRefills May Require Specialty Shops
VersatilityMay damage some markers, including electropneumaticsFine with all markers that don't use cartridges
Topping OffMust be emptied before it can be refilledCan be refilled between matches

Other notes:

  • All CO2 and compressed air tanks must be shipped empty as per Department of Transportation regulations. You will need to have your tank filled locally before use.
  • HPA tanks are filled via a fill nipple on the base of the regulator. One convenient feature of this is that you don't have to take the tank off the marker to fill it. Since the fill nipple acts as a one-way check valve you can just "top off" between games instead of having to drain and entirely refill, as you would with a CO2 tank.
  • Shop air compressors and tire pumps can't fill a compressed air tank. However, one common way of filling tanks is to use a scuba tank fitted with a Scuba Fill Station. A 3000psi scuba tank can between 15-20 fills. sells a variety of scuba fill stations for this purpose.
  • Compressed Air tanks are available in 3000 and 4500psi. 4500psi tanks can handle more pressure and thus yield more shots per fill. Shot counts vary between markers, but most spool valve markers and Tippmanns get about 10 shots per cubic inch at 3000psi and 15 shots per ci at 4500psi. More efficient designs such as Spyders and Egos can get even more shots.
  • Aluminum HPA tanks are up rated to 3000psi max. They are smaller and cost effective but weigh much more than fiber wrapped tanks. Fiber wrap tanks are rated to 3000psi or 4500psi (check your tank's label), cost a bit more and have more bulk but are a lot lighter.
  • Due to Department of Transportation regulations, all CO2 and HPA tanks should be tested every 3-5 years, depending on the specific make. Fiber wrap tanks have a maximum lifespan of 15 years. Steel tanks have a max life of 24 years. Aluminum tanks do not have a maximum lifespan, so long as they can pass hydrotesting.
  • Adjustable tank regulators used to be popular and necessary but now preset systems are the standard. Presets are available in High Output set to approximately 850psi, the same as CO2 under optimal conditions, or Low Output of approximately 450psi. Which do you need? Some markers out there need low output, like most Angels, or work best with one, such as Invert Minis. Most can use high output and blowbacks like Spyders and Tippmanns need the higher pressure to function properly. Again, refer to your owners manual to know for sure, or call us. We're glad to help.
  • Fiber wrapped tanks should always be used with a protective tank cover. They protect the tank from dings and gouges in the fiber wrap which can compromise the structural integrity of the vessel. A damaged tank cannot be filled or repaired.
  • Keep both HPA and CO2 tanks out of the sun when not playing.
  • Liquid CO2 follows the rules of gravity. When using CO2, try to keep the barrel tip of your marker pointed up whenever possible. This helps keep the liquid CO2 in the tank and not your marker's valve.
  • As a general rule, most markers get about 50 shots per ounce of CO2. Because of pressure differences you will get less in cold weather and more in hot weather.
  • If the weather is cool in the morning and significantly warmer later, always re-chronograph when using CO2. The warmer weather creates more pressure and your velocity will thus be higher.
  • An expansion chamber helps when using CO2. It provides additional chambers for liquid CO2 to convert from liquid to gas before entering the marker, thus yielding better gas efficiency and consistency. Using a coiled remote line can help in much the same way with the liquid expanding in the air line. If using CO2 with a remote, use a harness with a pouch that keeps the tank vertical instead of horizontal or liquid CO2 will be siphoned straight to your maker, like it was pouring through a straw.

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