Compressed Air vs. CO2 Use for Paintball
One of the most common questions beginning players ask is the difference between using Compressed Air (also referred to as Nitro, Nitrogen, N2, HPA or High Pressure Air) 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.
CO2 (Carbon Dioxide) 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, 12 Gram Cartridges (used in paintball pistols such as the Tiberius and Miltec and stockclass pump markers like the Phantom) and refillable CO2 Tanks. 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 (Pounds per Square Inch).
Using CO2 has some positive advantages. The tanks tend to be smaller and lighter than HPA while yielding the same or more shots 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 as well as paintball pro shops. The number one reason for CO2’s enduring popularity is cost. The 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. Because it is a liquid turning to gas it cools as it expands. This isn’t a big deal if you don’t shoot much but is very noticeable when shooting rapidly or a lot. The pressure begins fluctuating high and low with the result that your marker’s performance and accuracy begins to suffer. As the tank chills it begins drawing liquid CO2 up into the marker resulting in pressure spikes that can push velocities into unsafe speeds. If you see big white clouds of vapor coming out the muzzle and white snow falling out the barrel (its actually dry ice) when shooting you can bet that liquid worked its way into the marker. In cold weather the pressure can get so low that many paintball markers won’t cycle properly. Liquid CO2 is 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 and if you’re still not sure then call us.
Sound frustrating? It can be. Thats why players started using Compressed Air (HPA). Originally pure nitrogen was used, which explains why its sometimes referred to as N2, Nitro or Nitrogen Tanks. Rather than filling the tank with liquid they 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. 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 electropneumatic markers were designed with these tanks in mind.
HPA has three drawbacks. In some remote areas getting tanks filled can be a problem (tire pumps and shop compressors do not work, they rarely go over 180psi). The tanks tend to be a bit larger and bulky compared to CO2. Lastly, they do cost more than CO2 tanks.
HPA is the better investment in the long run. The benefits over CO2 in all-weather performance are well worth the additional cost. Besides, an HPA tank is a piece of equipment that can transfer to any marker you upgrade to. Determine what your needs are for your equipment and level of play and choose accordingly.
– 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. 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 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.
– Compressed Air tanks are available in 3000 and 4500psi. 4500 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 much 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.
– 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 or call us.
– 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 rechronograph 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 a straw.