Compressed air systems and Paintball

By Paul "Spider" McKay - June 2004

Compressed air systems and Paintball.

Some information you may want to know if you're thinking of getting a high pressure air (HPA) system for your marker.

Firstly:You need to make sure that the tank you own, or are about to purchase, complies with OSH standards. If you're not sure, ask your supplier to check for you. If it doesn't comply, don't buy it or use it!

To fill your marker's HPA system yourself you will need the following:

# A dive tank (preferably 3000psi rated or higher)
# A fill station suited to your marker's filling point (nipple) and suited to your dive cylinder (usually fairly standard)

Dive tanks come in many different sizes and shapes, but basically they are a cylinder with a valve on one end. They range from about 2200psi to 4500psi, although anything above 3600psi in NZ today is hard to find a place to fill them.

For filling your HPA system you will really want a dive tank that can hold 3000psi or more, having a cylinder that will only ever have 2200psi to start with will only give you a partial fill in your HPA system.

NOTE: Never use a dive cylinder with more pressure in it than the HPA system is capable of safely holding. COMPRESSED AIR CAN KILL

A fill station these days is a fairly cheap device and is fairly simple to operate. building your own is probably going to end up more expensive than buying one (I have made my own and ended up paying more than I could have for a rather flash one).

Filling your HPA system.

Most of you that have been using HPA systems will already have noticed that if you fill an HPA tank it heats up if you fill quickly, the fill is usually not a very good one either, you will end up having to top up the fill later on as the pressure has dropped since the initial fill.

This brings me to an important point… filling your system quickly generates heat and can actually raise the pressure that is inside the HPA system that is higher than what was delivered from the dive cylinder.

This can lead to a number of situations.

1. Nothing else occurs.
2. The burst disk blows.
3. Stress fractures are created in the HPA system, making it more susceptible to failing at a random time in the future.
4. The HPA system breaks, sending jets of high pressure air and possibly debris into the person filling the system, maiming or killing them.

The first situation is what most often occurs, but it can also lead to number three happening without any visible clues.

The second is annoying, especially as most people won't have a spare disk to replace it with.

The third is probably just as dangerous as the fourth, as you have no idea to when the HPA system will fail, it could happen in the middle of a game with the system being very close to your head.

To reduce the risk of damage occurring you should fill your system at a slower rate than just opening the valve and letting it fill as quickly as possible. Taking an extra 5 seconds to do a top up fill won't kill you...

If you're doing a fill on an empty HPA system, it is advisable to take it slow and let the heat dissipate as it builds up. taking 15 seconds to do a fill from empty is a little quick, try taking a minute or so. remember the air in the tank is compressing to over 200 times it's used to being at and it resists that compression by generating heat, and a lot of it.

Cylinder testing.

This is a topic that the NZPPA has addressed and has achieved some groundbreaking work of late. The have got a HPA system cylinder that is approved to compressed air storage for paintball in NZ (the cylinder on your HPA system) and got a hydro test schedule for it to ensure it is safe for use.

Hydro testing & Visual inspections why do I need to do this?

This is the testing of the cylinder of your HPA system that does the storage of the compressed air. Just like dive cylinders this must be tested for saftey regularly to comply with the law in New Zealand.

This is where they take the cylinder off the HPA system and check inside for cracks or corrosion (visual inspection) and test the cylinder to twice it's pressure rating using fluid to ensure it is still capable of holding compressed air safely (hydro testing).

It doesn't take long, it generally doesn't cost much, but it does give peace of mind that your cylinder won't explode any time soon.

Care of HPA systems.

Due to the construction of the cylinder and ease of damage to it, it's best to protect the cylinder with a bottle cover. This will stop knocks and scratches from damaging the surface of the cylinder, which can easily reduce its ability to contain the compressed air inside.

The cylinder is not the only thing you need to take care of, the regulator or valve (depending on your system) also needs care and attention.

If you alter the connections to the system (add or remove hoses, gauges etc) be careful you don't over tighten the bolts, this will lead to cracks forming in the housing and resulting in having to replace parts of the HPA system or worse, replace the entire HPA setup.

Tips on HPA systems.

Don't buy the cheapest… doesn't always work out that way in the long run.

Be wary of cheap second hand systems… get someone that has been using HPA for a while to check it out, they may be selling it for reasons you'd be better of leaving it.

Fixed or variable pressure systems… make sure what you're getting is what you need, not what you want...

Don't work on a charged (pressurized) HPA system results can be varied from scaring yourself stupid to killing yourself.

Conclusion.

HPA systems maintained and cared for will look after you in tournaments or in social play, you should look after the system the same you would for the rest of the marker.

Always remember;
Compressed Air is dangerous in the hands of fools.. don't be a fool.

Note: Always check with a trained professional before filling a tank. In the absense of information requested from OSH, the above is based on common international paintball best practices, and may not comply 100% with NZ safety standards. We recommend you confirm the above with them before use.