The biggest question we at ANSgear.com get besides what paintball gun should someone buy is “What is the difference between CO2 and Compressed Air tanks for paintball?”, or “What is better, CO2 or Compressed Air?”. Both are pressure sources that will make a paintball marker cycle and launch a paintball out the barrel, but that is where the similarities end. Depending on your marker, sometimes only one kind can be used without damaging your marker! To learn more, keep reading.

The first paintball guns such as the Nelspot 007, PGP and NSG Splatmasters used liquid CO2 and thus set the standard for many years. CO2 is Carbon Dioxide. When it turns from a liquid state into a gas it expands and creates pressure; this pressure is what fires the paintball. This pressure fluctuates due to elevation, temperature and other variables but the benchmark is 850 psi (Pounds per Square Inch). For paintball we use two types of vessels: disposable CO2 cartridges and refillable CO2 tanks, also known as CO2 bottles. Most disposables are in the form of 12 gram CO2 cartridges that are used in stock class pump markers and paintball pistols like the Tiberius T8.1. Refillable CO2 tanks are aluminum vessels with a valve (more on this below) and are filled by weight. The 20 ounce size is the most common.

CO2 bottles do have certain advantages. The number one reason for CO2’s long popularity has been cost. CO2 tanks are cheap, allowing players to buy several for a full day of heavy shooting play. Fills are relatively inexpensive, and if you don’t have a paintball pro shop in your vicinity then most welding and fire extinguisher supply shops can fill them for you. CO2 tanks are compact and yield a lot of shots for their size and weight compared to compressed air.

CO2 does have disadvantages that can impact your game. The number one drawback is tank and gun chilling. As the liquid CO2 is expanding it is also cooling; the faster it expands, the colder it gets. The more and faster you shoot, th pressure drops and affects the performance of the marker, losing range and then sputtering to a stop. The pressure begins fluctuating high and low with the result that your begins to suffer. The vacuum caused by the chilling sucks liquid CO2 up into the marker resulting in pressure spikes that can push velocities into unsafe speeds. Ever see big white clouds and white snow falling out the barrel when shooting? That’s actually dry ice and a sure sign liquid is in the gun. In cold weather the pressure can drop too low for markers to cycle. Liquid CO2 is hard on the seals of your marker and can damage the electronic solenoids of electropneumatic markers. Check your owner’s manual for compatibility, and if you’re still not sure then give us a call and we’d be happy to help you.

To combat CO2’s drawbacks, players started using Compressed Air. It is also known as High Pressure Air (HPA), or Nitro, N2 or Nitrogen Tanks since they originally used pure nitrogen. HPA tanks are pressurized up to the tank’s rating of 3000 psi or 4500 psi (Pounds per Square Inch). The pressure is then regulated through the tank’s regulator down to 850psi (High Output) or 450psi (Low Output). HPA’s #1 advantage is consistent pressure. The effects of firing fast or hot/ cold weather are negligible. No thick clouds or snow from the barrel, no more layers of frost on the marker body and your accuracy improves due to better velocity consistency. Today’s electronic markers were designed with these tanks in mind.

HPA has three drawbacks. If you don’t have a local pro shop then getting tanks filled can be a problem. Tire pumps and shop compressors do not work; they rarely go over 180psi. The tanks are quite a bit larger and more bulky compared to CO2. They also cost considerably more than CO2 tanks, three to twelve times as much.

Despite those drawbacks, compressed air systems win the CO2 vs. HPA debate. The benefits over CO2 in being able to play in all weather and at any firing rate alone pays is a huge performance and convenience upgrade. Besides, an HPA tank is an integral part of your equipment that transfer to any marker you upgrade to. Consider your needs, style of play and marker type to make your decision.

CO2 and HPA Tips and More Information:

- By law, 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. The exception to this is 12 gram cartridges and disposable one-time use CO2 cylinders, though they may be shipped by ground service only.

- All tanks have a hydro date. A hydro date is the month and year that the tank was officially safety tested. It is stamped near the neck on aluminum bottles and permanently printed on fiber wrap bottles. Typically the hydro date is good for 5 years (some economy fiber wrapped tanks are three years, as indicated on the label). The tank must be retested five years after the month on the tank.

- CO2 tanks are filled through the valve and must be completely drained before filling for a proper fill. Compressed air tanks are pressurized via a fill nipple on the side of the tank regulator. One convenient feature of this is that you don’t have to take the tank off the marker to fill it and you can top off between games instead of having to drain and entirely refill like CO2.

- 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 provide up to 15-20 fills. ANSgear.com sells a variety of scuba tanks for this purpose.

- Compressed Air tanks are available in 3000 and 4500psi. 4500 tanks 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 much more shots.

-HPA tanks are categorized by their Cubic Inches (ci) and their max PSI rating (typically 3000 or 4500). They are typically expressed as CI/PSI. Thus, a 48 cubic inch, 3000 psi air tank is a 48/3000 or 48/3k. A 68 ci 4500 psi air tank is a 68/4500 or 68/4.5k.

- Aluminum HPA tanks are up rated to 3000psi max. They are smaller and cost less but weigh considerably 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.

- 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 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 owner’s manual or give ANSgear.com a call.

- NEVER put oil or grease in the fill nipple of your HPA tank! A compressed air bottle heats up when being filled, from warm to hot. Keep all flammable material from entering the inside of the air tank.

- Fiber wrapped tanks should always be protected with a tank cover. A damaged tank cannot be filled or repaired. A good bottle cover keeps your investment from getting dings and gouges that could condemn it.

- Keep both HPA and CO2 tanks out of the sun when not playing. A CO2 tank left in the warm sun or a hot car can build up enough pressure to blow a burst disc. While an HPA tank will probably not overpressurize it is not good for the regulator’s seals.

- Gravity works on liquid CO2; if you point the barrel down, it will flow to the marker’s valve. Get into the habit of carrying a marker using CO2 with the muzzle pointed up.

- Most paintball markers get about 50 shots per ounce of liquid CO2. Because of pressure differences you will get fewer shots in cold weather and more in hot weather.

- If the weather is cool in the morning and significantly warmer later, always re-chronograph if using CO2. The warmer weather creates more pressure and your velocity will start increasing, possibly over the field’s maximum safe velocity limit.

- An expansion chamber helps when using CO2 by catching the liquid in additional chambers. This allows it to convert from liquid to gas better before entering the valve to deliver 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 gun like drinking from a straw.