CO2 Tanks/Refill

Question. When you refill a co2 tank, how much do you put in? example; 20 OZ, Do you weigh the empty bottle, say it weighs 3 OZ empty, then fill the bottle with 20 OZ of co2 so the weight totals 23oz? or do you fill the bottle weighs 20 OZ TOTAL. I went and had my 20 oz filled the other day and they told me they only put in 16 0z of co2.

My understanding is that they weigh the tank before and during so that they add 20 oz. of CO2 to it. 

Warm tanks are harder to fill as the CO2 expands from gas to liquid quickly when it comes in contact with the warm tank.  This is why you will see places "chill" the tank by putting a little CO2 in, then venting it out.  Depending upon the capabilities/skills/methods where you got it filled, 16 may be the best they could do.  I wouldn't get too worried as long as they are only charging you for 16.

Edited Addition:  Please don't "self-bump" your posts.  If you show a little patience someone will probably answer your question eventually.  If no one does, then nobody knows or is interested and the bumping probably won't help.  Additionally, self-bumping is annoying to other members, can be considered spamming under the forum rules and could make you go blind.


Edited by Mack - 14 March 2010 at 6:52pm