How do you correctly fill a CO2 cylinder?
Posted 26 March 2008 - 10:45 AM
Posted 26 March 2008 - 04:24 PM
Make sure bulk CO2 is strapped down, and a siphon tank.
Screw in CO2 tank. If it's fairly full, purge it all slowly. Too fast and dry ice will form, and you'll overfill. If it's mostly empty, purge it all quickly to chill the tank. If it's brand new or completely empty, fill a tiny bit and purge it.
Place tank on the scale, and zero the scale. Open the fill valve, and fill the tank, watching the scale. Fill a 3.5 or 4 ounce tank to 3 ounces, or 3.5 ounces, maybe a bit more if you want. 9 ounce to 8-8.5 ounce or so, 12 ounce to 11 or so, etc. Just leave a little room at the top, basically. If you're using a cheap, or non digital scale, leave more room. For your first fills, too, leave extra room until you get the feel for how fast it fills and everything. Some will say to leave more room, the guideline I give is typically the minimum amount of safety buffer I recommend. Shut off fill valve.
If possible, turn off the tank (like if your fill station has an on/off style asa for the tank) and purge the line. If you can't purge the line, just unscrew the tank.
If the tank is having trouble reaching full fill, you can shake it a bit. Usually it's just not cold enough or your bulk tank is empty. If it's not cold enough, you can purge a little more CO2 to chill it, then continue filling. You won't even need to reset the scale.
If the tank was new and needed a fill to purge a bit, you can put it on the scale, zero it, and usually filling one ounce for a 12-16 ounce tank is sufficient, bit more or less for 20 or 9 ounce tanks. Purge that air for the chilling. Then fill as needed. I usually just kinda do that by feel, if I need to add a bit of air to purge
While scales are safer and generally recommended, they're not typically necessary. The pressure in the small tank won't ever really get to be higher while filling than the bulk tank. The issue is that the small tank is colder, so when it warms back up, it gets to higher pressures. If you start using the tank right away, while it's still chilled, you'll usually use any air that would cause overpresuring before the tank has a chance to really warm up.
Not recommended, but in a pinch, if you forgot your scale at home or something, it's better to know how to still fill and prevent a bad situation than to just guess and have a burst disc blow while your marker is shouldered, know what I mean?
This post has been edited by aqua_scummm: 26 March 2008 - 04:35 PM
Posted 26 March 2008 - 04:44 PM
You need a bulk syphonning CO2 tank.
Scale. (PMI scales are great but hanging fish scales are ok. Table scales suck.)
Posted 27 March 2008 - 02:53 PM
the best way to learn how to do it correctly is to be shown how its done, observe how its done talking through the steps then doing it yourself under supervision.
i learnt how to do it working for fields, and now i still get called on by the field operator to fill bottles if all the referees are on the field and they are desperate!!
Posted 28 March 2008 - 08:52 AM