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Tips
How to properly fill a C02 tank
Welcome to "Tips from the Workbench". This month I will be discussing filling
your own C02 tanks.
Filling your small (3.5-20oz.) C02 tank is pretty simple, but you must follow
the guidelines within this article completely or this simple tank can become
dangerous. If you do not feel completely comfortable with filling C02 tanks
yourself, please don't. See your local Paintball retail store or air/gas
company.
What you will need: First and most importantly, to fill a C02 tank safely
you must use an accurate weighing scale. If you do not have one you will
either be overfilling or under filling the tank. Try using an electronic
(digital) fishing scale. Also you will need a "fill station" that has a bleed
valve, a fill valve, a pin depressor, and all of the correct size fittings
to fill C02. Unless you really are experienced with C02 filling and handling,
and you're going to build your own, buy a fill station made for Paintball
applications. If you're reading this however, you're not ready to put your
own fill station together, I guarantee it. You will also need an adjustable
or appropriate size box wrench to tighten down the fill station adapter to
your bulk tank. Of course you need a bulk C02 cylinder. It's also a good
idea to have some extra tank o-rings, and universal fill adapter seals (plastic
washer type).
About your bulk tank: Bulk tanks for filling small (3.5 - 20oz.) C02 cylinders
must contain a siphon (dip) tube. Dip tube tanks are either marked with red
paint around the top of the cylinder, or they are marked "dip tube" somewhere
on the tank. The dip tube hangs inside the bulk tank in the liquid C02 that's
in bottom half of the tank. The tube is used to draw the liquid C02 into
the smaller tank you are filling. This is necessary to get a good fill.
To empty the tank: To drain the tank you wish to fill, screw the C02 tank
into your fill adapter (a.k.a. Universal fill adapter) and "bleed" the tank
until it is empty. If you are emptying a siphon (liquid) tank, bleed the
tank in the upside-down position. This will "chill" the tank which will make
filling easier. For regular (gas) tanks, bleed the tank in the upright position.
If the tank you are filling has no C02 left you must chill it somehow or
you'll only be able to fill your tank to around 25% of its capacity. The
two common methods of chilling a tank are to put C02 (about two ounces) in
the tank then drain it completely, or place the tank you are filling in a
cooler or freezer for a short time.
To fill the tank: Filling a C02 tank is simple but it can be dangerous if
you are not careful. Screw the tank into your fill adapter and tighten down
the pin depressor until you feel resistance. Weigh the tank empty. With the
bleed valve closed, open the valve on your bulk tank and fill to the desired
weight. Since C02 expands when it warms up, it is much safer to under fill
your tank by about 15% or so. If you are filling a twenty-ounce tank, fill
it to about seventeen ounces. This way if the gas expands, your tank pressure
will not rise above safe levels. Close your bulk tank valve and unscrew the
fill adapter until you feel the resistance of the valve pin decrease
sufficiently. Bleed the excess C02 that's in the line and unscrew the small
tank.
Once you've filled the smaller tank, you'll need to wait until it warms up
to ambient temperature before you use it on your gun. If you don't wait,
your paintgun will either not work at all, or you'll get a very low chronograph
reading. Once the tank warms, your gun could be shooting at dangerous velocities.
That's my time for this month. Please play safe and wear only Paintball approved
goggles and play at organized fields. Thanks for reading.
(About the author...Rick Muncy is an Airgun Designs certified airsmith and
works at Pev's Paintball Pro-Shop in Woodbridge, Virginia.)
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