| PCRI Tech
Tips
Welcome to "Tips from the Workbench". This month I will be discussing the
differences between high pressure gasses and C02. We'll also look at the
benefits of using high pressure.
C02 & Compressed Gasses
For this article, we'll use the term high pressure when referring to nitrogen
or compressed air. C02 is a volatile gas that is greatly effected by temperature
and temperature changes. If you correctly fill your C02 tank, the internal
pressure will be about 850 psi (pounds per square inch) in 70 degree temps.
If you put that same filled tank in the sun, the internal pressure will rise
11 psi for each degree the tank warms up. In other words, if the tank warms
to 90 degrees, the internal pressure would rise to somewhere in the 1050
psi range.
If you chronograph your gun in the 290 feet per second range in the cool
morning, by afternoon you may be shooting 325 feet per second--not a good
thing. Even more dangerous is the fact that a black metal C02 tank, if left
in the sun, can easily heat up to 110 degrees or more. Conversely,
if you rapid fire your gun while using C02, you may "chill" your tank. This
will cause the pressure in your tank to drop, which will intern cause your
gun's velocity to drop accordingly. Again, this is not a good thing, but
there are a few things you can do that may help.
First, if you must use C02, try using a twenty-ounce tank. The larger tank
will be much more difficult to chill during rapid firing. Also, if your gun
is a gas-only gun (as opposed to say a Tippmann Pro-lite which shoots liquid
C02 well), you may want to take a look at using an anti-siphon C02 tank.
An anti-siphon tank has a tube attached to the inside of the valve that helps
prevent liquid C02 from leaving the tank. Another option is to use a remote
system. A remote system takes the tank away from the gun, providing space
for the liquid C02 leaving the tank to expand back into gas. This will help
keep your gun shooting consistently. With the exception of liquid shooting
paintguns, you should do what ever you can to prevent liquid C02 from entering
your guns valve system.
Why use high pressure? High pressure gasses used in Paintball (nitrogen and
compressed air) are much more stable than C02. Nitrogen and compressed air
are much less effected by temperature than C02. In other words, whether it's
20 degrees or 90 degrees outside, your gun will be shooting the same velocity
(give or take 3 feet per second). This results is a much more consistent
shot-to-shot velocity.
Another advantage of high pressure is that you don't have to wait for the
tank to warm after getting a fill. You simply fill the tank and you're ready
to play. Also, if you play with an on-gun high pressure system, you don't
need to remove the tank to fill it. Sounds great doesn't it? There is a down
side though. First, high pressure systems (hps) are expensive, running anywhere
from $250-500 retail. The high price tag isn't so bad if you're shooting
a $500 gun. Look at it this way, in the days of C02 only, anyone shooting
a 'Mag or 'Cocker had to by expansion chambers, filters, multiple C02 tanks,
regulators, and remote systems to get decent performance. These items can
easily cost more than a good quality high pressure system and still not give
you the best performance.
In addition to the price issue, high pressure systems give you less shots
per tank (equal size tanks) than C02. I'll put it this way, a 68 cubic-inch
hps tank when filled, will give you around 800 shots (using an Automag shooting
in the 280 fps range). If you used a 68 cubic-inch tank filled with C02 with
the same gun in the same conditions, you would get close to 1200 shots. The
bottom-line is that you'll need to carry a larger hps tank to get the same
number of shots that you would using C02.
In terms of safety, both C02 and hps need to be handled correctly to be safe.
I could (and probably will) write an entire article on how to keep your C02
and nitrogen systems safe. Is high pressure more dangerous than C02? I would
have to say no. Is high pressure for everyone? Certainly not. I wouldn't
put a high pressure system on a pump gun or a $100 semi-auto, but if you
want the best power source for your tournament gun, hps is the only way to
go.
(About the author -- Rick Muncy is an Airgun Designs certified technician
and works as an airsmith at Pev's Paintball Pro-Shop in Woodbridge, Virginia.)
Fax your questions to Rick at (703) 491-6391. |
