New CO2 Bottle - Emptying fast

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Hello, quick question.I bought a full CO2 bottle off eBay from a Nice guy in Kent who also fills them. BOC Size B Bottle (exciting, my first big bottle) advertised as a 14kg bottle. Not sure if its pub gas or straight CO2. For the type of welding I do it doesn't really matter.Anyway, when I attached my reg it showed 600psi (seemed on the low side to me, I was expecting 900psi?). I also assumed the CO2 would be in liquid form when under pressure but could hear no sloshing.After 10 minutes it was down to 200psi. Is this normal? I was running my low pressure line at approx 1.5 bar.I complained to the seller and got the follow reply:"Hi you won't hear sloshing as is gas and co2 regulators don't normally register them bottles as a lot as they are small the best test would be to take off the Reg and Check there is pressure and always turn off. If still an issue I can have refilled. But it was definitely full when you collected it" Can someone please advise if I've likely been sold a duff bottle and what I should look out for to make sure my replacement is full.Need advise as I don't want to cause a fuss if I'm in the wrong here.Thanks
Reply:Sounds like it was filled with has only and not a full liquid fill. If the tank has a rare weight on it you can weigh it and see if it has any liquid in it.
Reply:Co2 pressure is dependent on ambient temperature. Usually you will see 7-750 psi at 70 degree room temps. As the liquid boils off it cools the contents and drops the pressure. wait a bit and see if the pressure comes back up. I use 50# cylinders and see the variations all the time.
Reply:Mine is strapped down and I don't want to go unhook it to check but as I remember, you could definitely hear/feel movement when it was filled. I think your seller is wrong on that. I took mine to get certified and filled at a fill station that certifies and fills fire equipment tanks. They were closer than a welding supply store.You probably need to call other places locally where you're going to get it refilled and see what those outlets say.
Reply:I would think the 14kg listing would be the biggest clue whether it's full or not. 14kg is a weight measure, not a volume. That's 30 pounds of contents or it's not. That isn't a small amount. Did it feel like 30 pounds of liquid inside?"The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:.....Last edited by JD1; 03-19-2016 at 08:09 PM.
Reply:Thanks for your input (I'mmbring my bottle inside as suggested as see if that changes anything after a few hours).Have to say it was 14L, not 14kg. My mistake.With the reg it currently wieght approx 21kg. Can't find a weight on the bottle anywhere, nor online.Looking at the BOC website, Size B is 12L. So a liquid fill should contain 12 x 0.771 = 9.2kg of CO2.If mine is almost empty then a full bottle should be approx 30kg.I guess my question now is, is  gas fill a full bottle? Or does it have to be a liquid fill to be full?I read somewhere that the pressure will remain constant at 870psi whilst the bottle contains liquid. As soon as the liquid is gone, the bottle pressure will drop very fast and is tehcnically empty at this point. Can anyone confirm?
Reply:Originally Posted by montyjohnThanks for your input (I'mmbring my bottle inside as suggested as see if that changes anything after a few hours).Have to say it was 14L, not 14kg. My mistake.With the reg it currently wieght approx 21kg. Can't find a weight on the bottle anywhere, nor online.Looking at the BOC website, Size B is 12L. So a liquid fill should contain 12 x 0.771 = 9.2kg of CO2.If mine is almost empty then a full bottle should be approx 30kg.I guess my question now is, is  gas fill a full bottle? Or does it have to be a liquid fill to be full?I read somewhere that the pressure will remain constant at 870psi whilst the bottle contains liquid. As soon as the liquid is gone, the bottle pressure will drop very fast and is tehcnically empty at this point. Can anyone confirm?
Reply:Sorry friend, but you bought an empty tank that contained no liguid. Pure CO2 is just like Propane, where when the pressurized gas is in contact with liquid, the pressure will NOT drop until liquid has boiled completely off.....The only time you will see pressure change on full or partly full bottle is when temperature it is stored at changes.Properties of CO2 can be expressed on a PTR chart(pressure temp relationship chart), just like refrigerants and Propane. Every element is subject to what is called change of state....from gas to liquid to solid....Water is the most common example that you can SEE the changes at normal atmospheric pressures and normal Earth surface temps...There it remains water...heat it above 212 DF and it converts to gas...Lower it to 32 DF and it turns solid.I am a career long boiler engineer and most folks don't understand that the only way to depressurize a boiler full of water is to cool it to below 212 DF, or allow it to boil all the water out.......Same for many pressurized gases once pressurized to the liquid point.CO2 in it's "natural" state is gas...When compressed enuff it turns to liquid....even more it becomes ice....Just like water.You bought a tank with no liquid left in it.
Reply:OP, if you decide to return the tank to seller, then first weigh it as it sits.....After he fills it weigh it again to determine if it is actually full...Ignore the pressure as long as it has high positive pressure.
Reply:Originally Posted by wornoutoldwelderProperties of CO2 can be expressed on a PTR chart(pressure temp relationship chart), just like refrigerants and Propane.
Reply:New CO2 Bottle - Emptying fast
Reply:Originally Posted by pin2hotI have that problem with beer bottles.
Reply:To the original poster...next time you buy cylinder of liquefied gas there is super easy way to check if it is 85% full of liquid gas.Before you pay the guy, open bottle valve way open and allow gas to escape for a few seconds....Then shut valve and feel the bottle to see where on bottle it is COLDER to the touch....That location will reveal the height of the liquid level in bottle....That is where the liquid reacts to lower pressure the open valve offers and boils into gas state.On your gas grill once you fire it up on high you will either see a condensation line form at liquid level or at least feel it with your hand.