View Full Version : Co2 tank only holds 3 oz

10-12-2007, 10:43 AM
I have a 12 ounce Co2 tank and it will only fill up to 3oz. The fellow at ****s said he has never seen this happen thanks I need to replace tip on top tank. Any ideas?

10-12-2007, 11:52 AM
Did the guy fill it to 3oz, empty really fast and then try filling it to 11 or so? You have to chill the tank to make it take a full fill.

10-12-2007, 12:13 PM
I am not sure exactly what he did. He just switched over to a new co2 tank since the old was empy and I could see him trying to fill it but he could only get it to fill 3ozs. My tank has an antisyphin top -a thing on the side you can screw and unscrew. I have not messed with that. Would that have something to do with it? The guy said he never had any probs filling one what would make a tank do this does it need a new top?

10-12-2007, 01:21 PM
You mean its an on/off tank? Make sure its turned ON all the way

10-12-2007, 02:42 PM
This is what my tank looks like with the thing on the side of the nipple. I thought it screwed in and out but it does not. Not sure why it does not fill thought I need to replace the top part maybe.

10-12-2007, 03:07 PM
If thats the exact tank you have its only a 3.5 oz tank. The thing on the side would be a burst disk encase it is over pressurized.

10-12-2007, 03:09 PM
No that is not the exact one I have, mine is 12 oz. I just took that pic since it showed how the top of mine looks like. With little screw on the side

10-14-2007, 07:26 AM
Thats a burst disk its not made to move. It just sits there until a dumbass overfills your tank then it pops preventing the tank from turning into a grenade.

10-14-2007, 11:25 PM
OK.......well since I do 100's of fills per month i see lots of interesting things but I'm almost 100% sure of what happend. At the end of a CO2 tank you can't get a full fill. Alot of times when I can only get a 20 oz to fill up to capacity.....the tank is empty. Typically around the 3 - 4 oz level. Like you said he was switching tanks. Other problems it could be......I've seen alot of crappy valves on some of the tanks lately. Some have been causing excessivly slow fills. What's funny about the burst disk and CO2 fills and is hard to understand. Whether your CO2 tank is full or empty it always contains the same pressure as long as their is liquid. Over filling under filling CO2 does not cause more or less pressure. I will only fill customer tanks to what the bottle is rated to........however on my personal CO2 tanks I sometimes run over the normal fill amount. Do I recommend it.......no......but I fill 100'd of tanks per month We have games of over 200 players frequently........I have never blown a burst disk on a fill. Every blown burst disk I've witnessed has something to do with the bottle getting warm or hot. I can tank an almost empty bottle and blow it in 5 mins on the back of my truck. Or I can take a full bottle and put it under the truck in the shade and nothing will happen. CO2 has odd physical properties. The pressure of the tank has nothing to do with the amount of CO2 but only the temperature. Now granted if there is liquid it can happen faster because the pressure is in gas form and the less room for gas to expand the faster it will happen. Where we live in the winter your lucky to get 500 PSI from CO2. Earlier in the summer I showed someone my guage on a CO2 tank at almost 2500 psi when I left it in the sun as an example. Now that's not to say burst disks won't blow at random times..........they can.......they are just a piece of copper with an approximate burst pressure. Also there has been a long standing argument over whether they should be filled to capacity or not. Last time I checked with someone who went and took the PTI certified fill course they said it was fine to fill them to capacity.......but a slight amount under never hurt anyone!