Author Topic: Five pound CO2 tank fill -- what is full?  (Read 6674 times)

Offline howlinghound

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Five pound CO2 tank fill -- what is full?
« on: February 01, 2014, 06:04:16 PM »
Interested in your experiences with CO2 tank fills.  I recently had my tank filled and when I connected my dual-stage regulator, the tank pressure was 500 psi -- just at the top edge of the "red - running low zone"

Seems to me that the pressure ought have been higher for a fill but this was my first tank fill -- and rather than a weigh-based fill like I'm used to for propane tanks, this was a 'connect the gas bottle to my bottle and equalize pressure' approach -- to me, this seems flawed since a partially used filling tank will of course have less pressure than a full one... guess I thought there ought to be some weight based approach?

Thanks

Offline Stevie

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Re: Five pound CO2 tank fill -- what is full?
« Reply #1 on: February 01, 2014, 06:08:22 PM »
You are right, that method is flawed. I would find another source. I prefer airgas exchanges.

Offline In The Sand

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Re: Five pound CO2 tank fill -- what is full?
« Reply #2 on: February 01, 2014, 06:13:01 PM »
What temp is your bottle at? Pressure is a function of temperature so if the bottle is cold it will read lower, but it still has the same amount of CO2. If you store it inside the fridge with the kegs it will look low.

Alternatively, you may have a leak. Get some star San in a spray bottle and see if you can find it.
Trey W.

Offline howlinghound

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Re: Five pound CO2 tank fill -- what is full?
« Reply #3 on: February 01, 2014, 06:15:20 PM »
I would agree to look for leaks but this was the pressure when first connected to the regulator after I came home from the fill...  Wondering what others see as a "full bottle" pressure.

Offline hopfenundmalz

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Re: Five pound CO2 tank fill -- what is full?
« Reply #4 on: February 01, 2014, 06:23:21 PM »
CO2 tanks have gas over liquid. Co2 is a liquid at higher pressures. They make the tank cold by filling and purging, so they can get the full amount in. Look for the tare weight on the bottle, weight it and see if you have close to 5 pounds in (tare+CO2). Keep it at room temp and come back and check, the pressure may go up. If I put a CO2 tank in the keezer to carbonate lagers, the pressure is low on the tank gauge, but no worries.

Also note that the regulator will stay at a high pressure, until the liquid is gone, then it drops rapidly.

If they just equalized pressure, not a correct fill.

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Offline howlinghound

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Re: Five pound CO2 tank fill -- what is full?
« Reply #5 on: February 01, 2014, 06:29:37 PM »
Gas over liquid would be a fill process similar to that of a propane tank; as I was expecting.  This was not that.  I will look for alternate suppliers in my area.

Offline hopfenundmalz

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Re: Five pound CO2 tank fill -- what is full?
« Reply #6 on: February 01, 2014, 06:34:52 PM »
I would ask them how they fill. The source tank should have a dip tube so that liquid transfers. Search result.
http://www.specialopspaintball.com/forum/index.php?showtopic=75531

Weigh it, that will tell you.
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Offline Pinski

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Re: Five pound CO2 tank fill -- what is full?
« Reply #7 on: February 01, 2014, 06:39:50 PM »
CO2 tanks have gas over liquid. Co2 is a liquid at higher pressures. They make the tank cold by filling and purging, so they can get the full amount in. Look for the tare weight on the bottle, weight it and see if you have close to 5 pounds in (tare+CO2). Keep it at room temp and come back and check, the pressure may go up. If I put a CO2 tank in the keezer to carbonate lagers, the pressure is low on the tank gauge, but no worries.

Also note that the regulator will stay at a high pressure, until the liquid is gone, then it drops rapidly.

If they just equalized pressure, not a correct fill.
Is there a standard location for tare weight labeling? I use an exchange and my new bottles always have a new sticker on them that reads 4.5#. Of course that doesn't verify anything but it would be interesting to try and verify at home sometime.

My 20 pounder that charges my kegerator is finally dropping after about 2.5 years. Wondering if folks have a cut-off pressure that they disconnect from service lines to avoid mishaps or do you run them dry?
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Offline howlinghound

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Re: Five pound CO2 tank fill -- what is full?
« Reply #8 on: February 01, 2014, 07:03:04 PM »
I would ask them how they fill. The source tank should have a dip tube so that liquid transfers. Search result.
http://www.specialopspaintball.com/forum/index.php?showtopic=75531

Weigh it, that will tell you.


Thanks for the link and info.  This is more like what I would expect yet the tank used to fill smaller bottles was not a siphon tank and a simple gas connect hose was used -- so I expect that with equalized pressure approach, I ended up with a gas bottle filled with just that - gas.  No liquid transfer, no cold feeling to the flange.  And, when carrying the 5-lb tank back to the car, no feeling of sloshing liquid.

Offline hopfenundmalz

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Re: Five pound CO2 tank fill -- what is full?
« Reply #9 on: February 01, 2014, 07:13:59 PM »
I would ask them how they fill. The source tank should have a dip tube so that liquid transfers. Search result.
http://www.specialopspaintball.com/forum/index.php?showtopic=75531

Weigh it, that will tell you.


Thanks for the link and info.  This is more like what I would expect yet the tank used to fill smaller bottles was not a siphon tank and a simple gas connect hose was used -- so I expect that with equalized pressure approach, I ended up with a gas bottle filled with just that - gas.  No liquid transfer, no cold feeling to the flange.  And, when carrying the 5-lb tank back to the car, no feeling of sloshing liquid.

Then they are not doing it right, tell them. then find a new place.
Jeff Rankert
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Home-brewing, not just a hobby, it is a lifestyle!

Offline euge

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Re: Five pound CO2 tank fill -- what is full?
« Reply #10 on: February 02, 2014, 10:42:30 PM »
I used to get mine filled at a welding shop. They placed the tank on a crude scale and filled it. If the filler was a jerk I got less than 4# in a 5lb tank. But in their defense they obviously don't want it (unknown tank) to fail why they are standing next to it...

Now I get it filled at the lhbs by the lb.
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Offline klickitat jim

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Re: Five pound CO2 tank fill -- what is full?
« Reply #11 on: February 02, 2014, 11:23:18 PM »
Most of them tare is7.5 i think, full being 12 ish. Should be stamped on the collar.

Offline howlinghound

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Re: Five pound CO2 tank fill -- what is full?
« Reply #12 on: February 05, 2014, 03:04:08 AM »
Found a new place... bottle feels like it has liquid in it now and was weighed to fill.  Local welding supply.  Bottle was filled before I was finished paying for it...

Nice.