CO2 Ball Breakage

C02 Liquid/Gas Chart

Please note: This article is not intended to be a highly scientific explanation of CO2 gas properties that will have your reach for your scientific calculator. It is a practical article for everyday field play.

Because there's a lot of sources of ball breakage, it can be very frustrating to troubleshoot the source of your particular ball breakage. Of course some of the obvious possibilities are:

• Balls are warped
• Balls are too big for your barrel
• Debris such as paint, dirt, etc. in the barrel or hopper
• Balls are defective
• Bolt is chopping your balls (firing too fast, etc)

Ball breakage from liquid and solid CO2 is often overlooked and least understood yet it is probably one of the most common sources of ball breakage (and in the winter it's probably the main source). In fact, it's because CO2 can be a liquid or solid that drives some players to Air or Nitrogen tanks.

CO2, like all other gases, cools when it expands. When you release CO2 from your tank, you more than likely noticed how the tank cools. Your marker does the same thing internally (with or without a regulator). When the temperature of the marker or CO2 tank drops too low, the CO2 does not expand from a liquid into a gas completely. If you've dry-fired and noticed a very whitish vapor coming out of the barrel, you witnessed solid crystals of CO2 exiting the marker. Technically you are 'shooting solid' and not 'shooting liquid' because at atmospheric pressure (which is what the gas is at at this point), CO2 can only be a gas or solid (CO2 goes from a solid straight to a gas at atmospheric pressure without turning liquid.. also known as sublimation). If you've dry-fired the marker on your glove/hand during these conditions, you probably noticed some whitish CO2 solids deposited on it (but no CO2 liquid).

The two main sources of 'shooting liquid' are either cold weather or shooting very rapidly. However, the reason is the same for both: The ambient temperature-pressure of the CO2 while still in the marker is too cold/compressed to force the CO2 into a gas.

You've noticed how large droplets of rain have a significant impact. If these droplets of rain cool as they fall through the sky, they freeze and turn into hail. Hail of course can cause a lot of damage on impact. When you are 'shooting liquid', you are actually shooting a mixture of solid crystals/liquid/gas at the ball while the ball is in the chamber (remember that when you pull the trigger and the bolt fires, the gas escaping the bolt cools further as it is expanding.. because the pressure rapidly drops from i.e. 800 psi to 14.7 psi atmospheric pressure, the escaping CO2 can be a mixture of solid/liquid/gas while in the transition between these pressures if the temperature is too low or the pressure too high). Just like hail, these droplets and crystals can rupture the ball as any other projectile would.

So.. here's some points to remember so far:

1. CO2 can only be a solid or gas at atmospheric pressure (once it has exited the barrel)
2. Shooting liquid and solid CO2 at the ball in the chamber/barrel can rupture it
3. As the bolt fires and releases the CO2, the CO2 cools further and can force part of the liquid CO2 into solid crystals

So here comes the fine-tuned Pressure Regulator:

As you've noticed if you have a regulator, you can still 'shoot liquid'. However, a properly set regulator can help you eliminate ball breakage due to liquid/solid CO2.

Most paintball players know how useful regulators are but don't necessarily know at what pressure-temperature point exactly will prevent 'shooting liquid' as no marker (that we've seen) comes with a recommended temperature-pressure chart. At the top right of this page, there is a chart labeled 'C02 Liquid/Gas Chart'. This chart tells you at any given temperature, the pressure it takes to liquefy CO2. Therefore, a pressure setting greater than that indicated on the chart for the given temperature will result in liquid CO2 (and if the pressure is substantially high enough it may turn solid). Vice versa, a pressure setting lower than that indicated on the chart will result in pure CO2 gas.

So lets start with some examples.

• The ideal shot
  • It's now Oct 2004 and a temperature of about 60 degrees Fahrenheit up in the mountains is somewhat common around Boulder. This means that at 60 F, we can expect a mixture of liquid and gas at 747 psi in the marker. Therefore, if you leave the gun in the shade for an hour on the field and come back and take one shot while your regulator is 800psi, you will more than likely be 'shooting liquid'. However, at 600psi you would likely shoot ~100% gas.
• The reality
  • In the middle of the field, no player ever waits an hour for the temperature of their marker to match that of the ambient air to fire the next shot. Therefore, the internal temperature of your marker is expected to be anywhere around 10-20 degrees cooler than the ambient air (or even less if rapid fire). If you are playing in 60F weather you may want to set your regulator pressure no higher than 567psi which is the setting for 40F giving us a 20F degree margin of error (40F = 60-20) as the chart indicates. This ensures that the CO2 downstream from the regulator is all gas.

A few rules of thumb to remember:

1. Subtract at least 20 degrees from the ambient air temperature at the field and set your regulator equal to that or less than indicated on the chart. Another words, allow for a good margin of error.
2. OR better yet: Turn the volume/velocity adjustor on your marker to max and set your regulator to 300psi. Then, with the help of a chrono, increase your regulator pressure until you reach the desired velocity. But be sure that you do not go over the limit in step #1 or you may start breaking balls. In some cases, you may have to settle for a lower velocity than 300fps if you really dislike ball breaks.
3. A pressure setting of 450-500 PSI will probably serve you well year round unless if you are in feezing conditions.