Tech Topics - Paintball Basics

IMPORTANT: The information contained below is general in nature and is not intended to address every situation or every piece of equipment. You must get specific information about your equipment from qualified technicians at your local paintball shop.

Gas Safety

The pressures of the gases contained in paintball tanks and used to power paintball equipment are high enough to cause serious injury and even death. Unless you are a certified paintball technician trained in the use of these gases you should not attempt to repair or adjust the HPA or CO2 systems of your equipment.

CO2 tanks have a valve (usually brass colored but sometimes it is nickel plated) and HPA tanks have a regulator at the top of the tank. If the valve or regulator ever starts to separate from the tank, STOP, and take the tank to a paintball technician.

If you work on your paintball marker be sure to remove your tank and completely degas the gun before starting any work on the gun.

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CO2 and HPA

Many players ask about the differences between CO2 (Carbon Dioxide) and HPA - commonly known as Air or Compressed Air or Nitro or Compressed Nitrogen. Although compressed air and compressed nitrogen are used interchangeably in paintball many players prefer compressed nitrogen since it is a single gas and not the mixture of the gases that make up air. Some markers must use HPA; some can use either CO2 or HPA.

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Tank basics – CO2 Tanks

Today’s refillable CO2 tanks are made of aluminum and come in a variety of sizes with typical sizes ranging from 4 ounces to 24 ounces. Some older CO2 tanks are made from Molly (Chromium/Molybdenum steel). These molly tanks are heavier than aluminum tanks and are no longer available. CO2 is also sold in small disposable aluminum cartridges; you may have seen these used in soda water dispensers. These come in several sizes but the most common ones available for paintball are 12 gram cartridges.

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Tank basics – Nitro Tanks

There are three basic types of HPA tanks. The least expensive are made from Aluminum (many players call them Steelies) and come in four sizes – 13 ci (Cubic Inches), 48 ci, 62 ci and 72 ci and hold 3,000 psi (Pounds per Square Inch). The other two types of tanks are fiber wrapped tanks. These tanks have an aluminum core and are wrapped with a resin that contains either fiberglass or a combination of fiberglass and carbon fiber. These tanks are then encased in gel coat which gives them their glossy finish. These tanks also come in various sizes ranging from 45 ci to 90 ci. Some older tanks were even bigger. Most fiber wrapped tanks produced today hold 4,500 psi.

Although an HPA tank contains 3,000 to 4,500 psi, the regulator on a paintball tank will reduce the output pressure of the tank. Most commonly the output pressure is set to about 750 psi which is the typical output pressure of a CO2 tank at room temperature. Some tank manufacturers offer a choice of output pressures of a paintball tank - usually a low pressure option which might be 450 psi (every manufacturer has their own specifications for what they consider to be “low” pressure) and a high pressure option (again, each manufacturer has their own definition of “high” pressure). Additionally, there have been tanks manufactured with a variable regulator which allows the operator to adjust the output pressure over a range of pressures.

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How Many Shots - CO2?

With CO2 you will get about 40 shots per ounce so a 20 ounce tank will typically give about 800 shots per fill. Keep in mind that every marker is different and many factors can change the number of shots you can get from a fill including the velocity you are shooting, the cycle rate of your shots, your particular gun and even the weather. The higher the velocity the fewer shots you will get and in warmer weather you might get a few more shots than on colder days. 12 gram cartridges will give 15 to 30 or more good shots in a typical paintball pistol and then another 15 to 30 shots with lower velocities.

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How Many Shots – HPA?

Just like CO2 tanks, a wide range of factors will influence how many shots you will get from a HPA tank. Obviously, a bigger tank and a higher pressure in the tank will provide more energy for more shots. Other factors that influence how many shots you will get from a tank are the velocity, cycle rate and the efficiency of your particular marker.

One thing to consider with HPA is that the useable capacity of a tank is less than its rated pressure. For example, if you are shooting a typical Tippmann 98 Custom with HPA, when the tank pressure drops much under 750 psi your gun will stop working or will only work with reduced velocity. So the useable capacity of your 3,000 psi tank with this gun is 2,250 psi (3,000 less 750 = 2,250). With a 4,500 psi tank the useable capacity is 3,750 psi (4,500 less 750 = 3,750) an increase of useable capacity of 67%.

Some markers can accept lower input pressures than others and still function. These markers are able to use more of the HPA’s energy and will enable the user to get more shots. However, some markers will not function properly at low pressures and these guns will not work with a low pressure tank.

A 48 cubic inch, 3,000 psi tank will give you about 400-600 shots.

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Can I fill my HPA tank from my shop or garage air compressor?

You can probably guess the answer to this. No, you cannot fill a paintball HPA tank with your home compressor. Most home or shop compressors produce 125 to 150 psi. This is not even close to the pressure needed to fire your marker or fill the tank.

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Can I put compressed air into a CO2 tank or CO2 into an HPA tank?

Again the answer is no. Filling HPA into a CO2 tank would break the burst disk and CO2 could harm the regulator/tank of an HPA tank.

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Can I fill my HPA paintball tank from a SCUBA tank?

Yes, you can. You will need an adapter that will fit on the SCUBA tank and that has a coupling that will fit on the fill nipple of your paintball HPA tank. These adapters do not regulate the pressure coming out of the SCUBA tank so you must insure that the pressure in the SCUBA tank is not more than the pressure allowed in your paintball HPA tank. If, for example, you have a filled 3,000 psi SCUBA tank, you will be able fill your paintball tank up to the 3,000 psi in the SCUBA tank. Each fill will take some of the pressure from the SCUBA tank so the second fill from the SCUBA will be a little less than the first, the third fill will get a little lower pressure than the second and so on.

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Which is better CO2 or HPA?

There are a number of factors to consider when answering this question. CO2 tanks are less expensive than HPA tanks. For the same size tank, you will get a lot more shots from a CO2 tank. However, CO2 is a liquid in the tank and it takes a little time and a little warmth to convert the liquid CO2 into a gas which is what operates the gun. HPA is always a gas and does not have to convert from a liquid to a gas. Although the amount of time needed for CO2 to convert to a gas is small, it does take a little time and when you are shooting rapidly, especially in colder weather, the pressure in the CO2 tank will decline and the pressure will drop. You may experience a drop off of the velocity of your shots and even see “snow”, which is frozen CO2, going through your gun and out the barrel.

Almost all paintball markers can operate with HPA. Some can use either CO2 or HPA. Some guns, especially higher end guns and guns with high rates of fire and/or electric triggers must have HPA. Many of these guns will be ruined if you use CO2. We recommend using HPA with any gun that has an electronic trigger.

So, both gases have their pluses and minuses. Check with your paintball store to see what they recommend for your marker.

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My CO2 tank started hissing and got freezing cold – what’s up?

What probably happened is that the burst disk on the tank broke. The burst disk is a safety pressure release devise. It is a copper disk that is held in place by a nut. If the pressure of the tank gets high this disk will break and release the CO2 in the tank. This is a safe way to relieve high pressures without breaking the tank itself. The burst disk can be replaced and the tank will still be useable. Burst disks can break if the pressure in the tank gets too high, such as if the tank is left in the hot sun or near a heater, or they sometimes break just due to age.

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My HPA tank “popped” and all the air went out - what’s up?

Just like the CO2 tank, what probably happened is that a burst disk broke. However, in the case of HPA tanks, the tank will not get cold. Like the CO2 burst disk, the disk broke when the pressure exceeded the strength of the burst disk. Again the disk can be replaced, but you should check to make sure there is no problem with the tank itself.

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Can I use a HPA burst disk to replace the burst disk of my CO2 tank?

Sorry, but no. Burst disks have ratings to reflect the pressures that they will sustain. It is unsafe to use inappropriate burst disks on your tanks. Don’t use CO2 burst disks on HPA tanks or HPA burst disks on CO2 tanks. Additionally HPA tanks use different burst disks depending on the tank’s rating (3,000 or 4,500 psi) and whether the burst disk is on the tank side or the output side of the regulator.

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What is a Hydro Test and why do I need it?

Hydrostatic tests help determine the durability and safety of a tank. Aluminum CO2 tanks that are over 2.5 inches in diameter (some 9 ounce and most 12 ounce and larger tanks) must have a current hydro test certification. This certification is valid for 5 years after which the tank can no longer be legally refilled until they are retested. Retesting of tanks must be completed by certified technicians.

HPA tanks also must have a current hydro test date in order to be filled. Aluminum HPA tanks must be tested every 5 years. Most fiber wrapped tanks must be tested every 5 years, but some have to be tested every 3 years – this varies based on the exact tank and can be determined by the DOT number on the tank.

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