There are a lot of myths surrounding the various propulsion gasses used in paintball. We are going to try to debunk some of them and give you the information you need to make the proper choice for you!

* HPA - High Pressure Air
o This is the most common name for compressed air. It is nothing more than the air we breath compressed to 3000, 4500, 5000 psi.
o It is a very clean source of propulsion if it is filtered at the compressor. If not, then it contains all the dust and pollution present in the air where the compressor is located. Check with your local field to see what steps they take to ensure you get a clean fill.
o It is highly consistant. The pressure inside the tank, and that going into your marker, will remain at a constant pressure throughout the shot range. This ensures shot A is going the same velocity as shot V.
o It helps with accuracy by remaining consistant. This means your trajectory arc is going to remain the same from shot to shot, thus allowing you to know where all subsequent shots are going in relation to the first one.
o It is expensive. Since the construction process for HPA tanks is more inclusive, the tank costs a relatively considerable amount of money compared to a CO2 tank.
o It is generally a recommended propulsion source by many marker manufacturers, though only a select few markers actually require it to operate properly.
o It is a plug and play system. Screw the tank into any marker and you are ready to hit the field. No muss, no fuss.
o Tanks come in various sizes. The most common size is the 68ci tank. To get a good “guesstimate” of your shot:fill ratio you need a little math. Multiply the ci of the tank by the pressure it holds (3k, 4500, 5k) by 10, 15, 17 respectively. If you have a 68/4500 then 68 x 15 = 1020 shots.
o You will need to have your tank hydro tested every few years (3-5 depending on the manufacturer specifications). You will probably have to send your tank out to have this done, though some fire stations are equipped to do such tests.
* Nitro – Nitrogen – N2
o In paintball terms it is fully interchangeable with HPA and acts exactly the same in the marker for propulsion purposes.
o Chemically it is much different, composed entirely of nitrogen molecules.
o An expensive alternative if HPA is not available for your tank.
o I’m not going to go in depth on this as N2 fills are the exception instead of the rule.
* CO2 – Carbon Dioxide
o A bi-product of other chemical processes, CO2 is still the most common paintball propellant to be found in use today.
o Depending on the source, CO2 can contain contaminates from the manufacturing process.
o It is stored in a liquid form inside the tank and actually boils off into the gas used by the marker. Since this phase transition (more appropriate description) absorbs heat, the tank will frost over from the condensation in the air. Wrapping a CO2 tank actually slows the process of phase transition by insulating the tank from heat absorption, so don’t wrap it up in wool socks so you can play in the winter… no matter what that big white bear says wink.gif
o The pressure fluctuates depending upon many factors (ambient temperature, temperature of the liquid, rapid shooting, etc). This makes it an inconsistent propellant without help.
o Many of the o-rings in your marker can freeze and expand if exposed to the CO2 liquid.
o It rarely exceeds 1100 psi inside the tank. There is a burst disk designed to release the pressure if it climbs to dangerous levels (prolonged exposure to sunlight or heat sources, etc).

Myths common among the paintball world

* CO2 is dirty!
o It can contain contaminates due to the manufacturing process. However these have a very negligible effect on your markers operation in most instances.
* CO2 will ruin your marker!
o A properly setup CO2 system ensures that no liquid will get into your marker. This includes an anti-siphon tube (small bent tube inside the tank that ensures only gas is drawn during the shooting process) and a CO2 tolerant regulator (the Palmers Stabilizer is the best choice for this… though expensive it has been proven through the years and is extremely reliable).
o There is very little damage that CO2 can cause to a marker. Carbonic acid can occur if the CO2 is mixed with water inside your marker and left for extended periods of time (You do clean your marker after every game day don’t you?). The concentration of this acid is so weak during a regular gaming session that no damage is caused.
o Liquid CO2 can cause problems for rubber components inside your marker. For this reason it is generally not recommended for markers whose operation depends on an air solenoid unless you take steps to ensure no liquid enters the marker.
* CO2 will freeze your marker and make it stop working.
o In a properly setup system this is virtually impossible. However, it can happen on a base system (without anti-siphon and regulator) under rapid fire conditions or winter games. The “freeze up” is nothing more than swollen o-rings inside the marker causing excess friction and seizing up the action.
o Many markers on the market today can be setup to run on liquid CO2. This uses the stability of pressure from the liquid and the action of the valve (rapid pressure release, etc) to operate the marker. It is still in use today and is a great example of debunking this myth!
* CO2 is inconsistent!
o While actually not a myth it is being presented as one due to the over use of this statement.
o CO2, in a base system, is extremely inconsistent. It can lead you to dangerous velocities on the field, penalties at the chrono, and some very wild shots. You can control this through a proper setup. With an anti-siphon and regulator you can get a shot to shot consistency that equals HPA in all ways. The Palmers Stabilizer has a pressure ratio (input:output) that can even out any of the pressure fluctuations and transfer this into 10psi or less change inside the marker under all conditions. This equates out to +/- 3 to 7 fps at the chrono!
* The cost to setup a marker for CO2 vs HPA makes HPA better.
o This all depends on what is available to you. If your field only offers CO2 fills, then $200 for an HPA tank is a waste of your money.
o Some fields are offering HPA only. In this case you still get the benefits of the regulator from a CO2 system and the only wasted money you spent was $5-20 for an anti-siphon tube.
* I need special stuff to switch to HPA.
o The only thing you need is the tank! It is a plug and play system, meaning you can screw in the tank and hit the field. Just make sure you check the velocity at the chrono before going.
o Special care does need to be taken in the way you handle your new HPA tank. Deep gouges, scratches, or cracks in the outer shell of a fiber wrapped tank can be very dangerous and render your tank unusable. Get a tank cover, they are a great investment to protect your tank.
o A secondary (on marker) regulator is not needed, but is very good to have. The pressure coming from an HPA tank is 850psi or so on a high pressure output tank. This is adequate to operate any marker out there, but is excessive for those markers designed to operate on low pressure. In this case a low pressure output tank is necessary.

I’ve only touched on a few of the myths and a few of the explanations regarding the differences between these propellants. In the end the choice is yours. Hopefully you now have a bit more knowledge to make an informed decision instead of relying on responses from people who perpetuate the myths surrounding our great sport!

*cross posted from the Air Systems Forum*