# Full 5lb co2 weight?



## gSTiTcH (Feb 21, 2013)

I don't know about the weight issue.

I do know that the pressure will vary depending on ambient room temperature. Tank pressure also varies a little depending on fill level, but is almost indiscernible on the gauge until the liquid goes away.


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## gus6464 (Dec 19, 2011)

Aren't CO2 tanks measured by weight of containing gas, so by definition a 5# CO2 can will hold 5lbs of CO2.


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## Mathias1324 (Jan 28, 2013)

gus6464 said:


> Aren't CO2 tanks measured by weight of containing gas, so by definition a 5# CO2 can will hold 5lbs of CO2.


Yeah it will hold 5lbs of liquid but I don't think you're supposed to fill it all the way because you're supposed to leave room for the gas to expand as it warms. I think so anyway. I was looking at this chart for the co2 pressure/temp/fill % relationship and even at 100% fill the pressures don't go above 1000psi at 80F. But I've seen people post on here that their regs are reading 1500psi and up at room temp on an overfilled tank. Idk. Maybe I'm just worrying for nothing, especially since I don't even know what the pressure is yet, but I'd like to sort this out for peace of mind.


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## PlantedTankRookie (Feb 21, 2013)

Most tanks have a pressure relief so worst case is the cylinder vents a little if the pressure is too high. The "minimum blow out" pressure is likely the relief lift point.
Also, the test pressure on these cylinders includes a decent safety margin so I wouldn't worry about it.
I'd get a little nervous if I saw 2000 lbs on my gage but I doubt you'll see that.


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## PlantedTankRookie (Feb 21, 2013)

A quick google search shows typical test pressure of 3000 psi.


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## Bluek24a4 (Mar 16, 2010)

Your 5 pound tank is filled with 4.3 pounds of CO2. It seems like you're underfilled. You should be fine. Maybe he meant he couldn't get the pressure up on the fill station and thus it couldn't fully fill your cannister.


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## Bandit1200 (Dec 11, 2010)

When I get my co2 filled in the summer, I always ice it down on the way to the shop. Depending on the temps, I've gotten as little as 2lbs before I started doing this.


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## Mathias1324 (Jan 28, 2013)

Well, there I go worrying for nothing lol. She's all set up and running smooth. Gauge reads 875 on the high and the tank's been sitting for about 7 hours, so it should be around room temp. Crap, I always switch to panic mode too fast haha. Thanks for all the replies.


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## exv152 (Jun 8, 2009)

Ambient temperature is definitely key, but at room temperature roughly 72degrees, here's an approx chart for tank weights full and empty.


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## gus6464 (Dec 19, 2011)

exv152 said:


> Ambient temperature is definitely key, but at room temperature roughly 72degrees, here's an approx chart for tank weights full and empty.


Nice guide! So for 99% of people a 5# tank should contain 5# of co2 when full.


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