# Pressurized Co2 Safety



## Centromochlus (May 19, 2008)

As many of you know, i got a severe second degree burn on my leg from liquid co2 last January. Considering that if i would have had my head down for about 10 seconds longer, i would have gotten my whole face burned, i really want to make sure i know how to do this the RIGHT way (and yes.. i know, i shouldn't have been holding the tank in between my legs). Even though it was a bad experience, i'm still eager to get another setup. However, when i jumped into the world of pressurized co2, i did not research the safety of transporting and keeping pressurized tanks. I'd like to make sure i'm prepared in the event that i do get another tank, and i'd like to have some information to present to my parents (who are currently mostly against the whole pressurized co2 thing).

Let me walk you through what happened, just to see if anyone can point out any major issues:
1. Drove to LFS, got there and the employee got the full 10lb tank out of his hot car (he said it had been sitting there for a few hours). 
2. Left LFS. Stopped at the grocery store, left the tank inside the car for 15-20 mins (i know, bad idea).
3. Attempted to set up co2 system at home, but the regulator wouldn't screw on properly.
4. Drove back to LFS, nearly 2 hours AFTER we purchased the tank. On the way there, the tank depressurized in the car.

But what i'm wondering is if this was enough time for the tank to "cool down". Or does it take way longer for there to be a significant loss of pressure do to cooling outside temperature? Because here's how it went: 2hrs inside employee's hot car, 15 minute drive in cool car, 15-20 minutes in hot car, 1hr+ in cool car, then safety valve blows.

I know the issue is probably heat- but based on the information below, it wasn't nearly hot enough for the tank to depressurize. It couldn't have been more than 90 degrees inside the car (which isn't all that hot in AZ).

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_" . A CO2 cylinder is filled with liquid CO2 by weight. At the time of fill the temperature of the charge is extremely cold and the pressure is around 100 psi.

. When a fully charged CO2 cylinder warms up to room temperature (70 F), the pressure inside the cylinder increases to 837 psi.

. When the same cylinder reaches 87.9 F the entire charge becomes a gas no matter what the pressure. A fully charged CO2 cylinder at 87.9 F will have an internal pressure of approximately 1100 psi.

. At 120 F the same cylinder will have an internal pressure of nearly 2000 psi. This cylinder at 120 oF now has an internal pressure greater than the marked service pressure of a cylinder that is properly filled, not overfilled.

.	At 155 F the same cylinder will reach a pressure of 3000 psi, a pressure great enough activate the safety vent on the valve, venting the CO2 charge."_
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So here's what i'm wondering: Was heat a huge issue, or could it have been overfilled + heat = disaster? The safety valve did open, causing the liquid co2 to be rapidly released. 

*My questions*:
1) That being said, what is the proper/safe outside temperature to keep pressurized tanks in? My house temperature is usually around 78-80 degrees; could this be an issue?
2) Would keeping the tank a little less than full be a safe idea, due to the extreme heat that we sometimes get in Arizona?
3) What's a safe PSI range? Some websites are saying below 1500PSI, while others are saying below 1000PSI.
4) Does anyone have any other safety recommendations? I know events like this are pretty rare (i've only been able to find a few other cases, which were both VERY similar to mine), and i'm sure most of you haven't had any problems with your co2 tanks- but what precautions do you take? One of my local friends recently told me the proper way to transport pressurized tanks in AZ, so i got that covered...
5) How long would a paintball or 2.5lb tank last on a 150g? LOL. 

Thanks for your help in advance.


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## oldpunk78 (Nov 1, 2008)

oh man - you guys pretty much did everything wrong. the guy at the lfs should have known better than to leave a full co2 tank in his car and let it just sit there. 

the place i get mine filled at won't even fill mine for me unless my tank is frozen. 

inside your house(@78-80F), after a day or so of having the tank filled, it should be about 900psi. i would think you'd be fine at up to 1500psi(it shouldn't be though). when i first hook up a new tank, i notice that the tank pressure might get up to 1200psi before the tank and the house have reached the same temps. 

your local temperature shouldn't have anything to do with looking into a co2 system. just think about all of those fire extinguishers out there that use co2. that being said, i'd like to answer the outside temp question. outside temps where i live can get pretty hot too. it stays around 100F all summer. last summer i think the hottest day we had was 118F. i work in a mill which is a metal building with no a/c. non of our co2 extinguishers depressurized...


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## Postal Penguin (Mar 30, 2009)

Next time suggest to the filler that he fill it with maybe a 1/4lb of CO2 and then crack the cylinder open so that CO2 instantly vents. It will flash freeze the tank and a) cool it down b) you'll get a better fill out of it. I have had a paintball tank release because the shop clerk filed it warm so it maybe the root cause of the problem. 

Question 2: I don't think keeping it less full will do anything because CO2 in these tanks is at a liquid/gas equilibrium state so the pressure will remain constant until nearly empty. 

Question 4: I transport my CO2 tanks in the car by placing them in the back seat foot wells. That way they get AC quickly, aren't in the hot trunk and if they explode they wont be under your feet.


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## jinx© (Oct 17, 2007)

The only time I've ever had a burst disc/safety release yadayada blow was from tanks being improperly filled and/or overfilled. 
Tanks have to be chilled prior to filling. Any reputable outfit will know this, and how to go about properly filling your tank.

I've dealt with tanks from 9oz. to 200lbs in the fields of paintball, aquariums and welding and have never had an issue with transport, temperature, storage etc. I've played paintball, worked and stored tanks in pretty much every environment you can think of with no crazy catastrophes. 

I'm in no way saying that bad things can't happen, It's always a present danger when dealing with pressurized gases and varying equipment. 

Read up some more, and most importantly just take your time and use common sense when working with your setup.


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## OverStocked (May 26, 2007)

Next time get the tank and fill done yourself at the fill station, and cut out shady LFS workers.... 

I work with pressurized oxygen and liquid oxygen tanks(literally the tank is always leaking... it has to be kept so cold to keep it in the tank that it is part of life) and we have little fear because we know they are filled responsibly and the tanks are kept responsibly. 

GO to a gas supply house to have it filled. THey do the job correctly.


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## VadimShevchuk (Sep 19, 2009)

i would go to a welding shop and just do a swap/refill sinc ethey fill tanks everyday and they know what there doing. LFS probably fills a tank once a week. Just talk to your parents and tell them that they shouldn't sit on the couch since it might break and they could get injured. The point is that everything is dangerous and accidents happen even though they are rare.


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## Centromochlus (May 19, 2008)

Thanks for all of the information. I know we did pretty much everything wrong, so maybe presenting them with safety information will convince them that it's worth trying again (the RIGHT way). 

I know it might be hard to tell, but does anyone know what might have been the cause of this happening? I didn't think it was hot enough for the tank to reach 3000 psi, but could it have been perhaps overfilled? Or was it really hot enough for the safety valve to blow (even though according to the information in the first post, it would have had to been at least 155 degrees)?


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## OverStocked (May 26, 2007)

I would suspect it was overfilled. The shop I fill my tank at is open air(big garage doors always open) and it reaches 100 in there often and they don't have any problems...

The shed we store liquid o2 in is just a metal box... it gets well above 100 in there, and yes, liquid o2 leaks out because to keep it liquid means keeping it wicked cold, but I don't think I'd even think about it blowing.


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## Centromochlus (May 19, 2008)

over_stocked said:


> I would suspect it was overfilled. The shop I fill my tank at is open air(big garage doors always open) and it reaches 100 in there often and they don't have any problems...
> 
> The shed we store liquid o2 in is just a metal box... it gets well above 100 in there, and yes, liquid o2 leaks out because to keep it liquid means keeping it wicked cold, but I don't think I'd even think about it blowing.


Haha... that's what i was thinking. We probably could have sued them.


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## OverStocked (May 26, 2007)

For the record, liquid o2 is far more dangerous and it is also carried in helicopters for medical transport over much more stable compressed o2.

was the tank in the upright position or laying down? They really should stand and be transported upright, as it could have allowed a pressure buildup inside the fitting...


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## Centromochlus (May 19, 2008)

over_stocked said:


> For the record, liquid o2 is far more dangerous and it is also carried in helicopters for medical transport over much more stable compressed o2.
> 
> was the tank in the upright position or laying down? They really should stand and be transported upright, as it could have allowed a pressure buildup inside the fitting...


The reason i was holding it in between my legs was to hold it upright. I should have strapped it in the back seat though.

Now is liquid o2 in scuba tanks? My brother scuba dives, and i've mentioned to my parents that my brother has one of these tanks ON HIS BACK, while i would have one in my aquarium stand. But they think o2 isn't as dangerous as co2.


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## OverStocked (May 26, 2007)

no, those are compressed air(oxygen/nitrogen). Not liquid. Remind them that co2 is used in fire extinquishers... oxygen will FUEL a flame, co2 would put one out.


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## Centromochlus (May 19, 2008)

over_stocked said:


> no, those are compressed air(oxygen/nitrogen). Not liquid. Remind them that co2 is used in fire extinquishers... oxygen will FUEL a flame, co2 would put one out.


True. Well i have lots of information to present to them, so we'll see how it goes.


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## Centromochlus (May 19, 2008)

Thank you to everyone who contributed information. My parents are going to let me try co2 again once i have enough money to purchase everything. In the meantime, i'll continue to do some research.


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## mrbhala (Sep 13, 2018)

Postal Penguin said:


> Next time suggest to the filler that he fill it with maybe a 1/4lb of CO2 and then crack the cylinder open so that CO2 instantly vents. It will flash freeze the tank and a) cool it down b) you'll get a better fill out of it. I have had a paintball tank release because the shop clerk filed it warm so it maybe the root cause of the problem.
> 
> Question 2: I don't think keeping it less full will do anything because CO2 in these tanks is at a liquid/gas equilibrium state so the pressure will remain constant until nearly empty.
> 
> Question 4: I transport my CO2 tanks in the car by placing them in the back seat foot wells. That way they get AC quickly, aren't in the hot trunk and if they explode they wont be under your feet.



I had an issue of frozen co2 cylinder after filled up. I enquired and did some research in the net. With my little knowledge i wanted to highlight, there is max legally safe filling capacity for co2 at standard pressure. 68% to 75%. It varies on different standards. But overfilled is dangerous at increasing temp and PRV will get opened. Fill for safety level, keep upright, avoid to much of temp. Fire extinguisher is different in the case of temperature handling as they have drop tubes inside.


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## jeffkrol (Jun 5, 2013)

AFAICT burst discs open at about 2500-3000psi..


> 1. Carbon dioxide is stored in cylinders as a compressed
> liquefied gas and any increase in temperature will cause an increase
> in pressure. Consequently the pressure in the cylinder is not a
> reliable indication of the contents. To protect cylinders against overpressure,
> ...


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## PlantedRich (Jul 21, 2010)

Any time that I read posts like this, especially this old, I am reminded of a big point that is often missed. The new user who is afraid of CO2 tends to panic when a small event happens and then it can go from being a small event to something much larger. At least in their newbie mind! 
Big point on CO2 safety is to think of how many thousands of people in really wide ranging jobs use CO2 dailly without hurting themself. Think of the kids behind the counter at the local burger joint that use CO2 to make the soda? How about the semi-drunk bar tender? They work with tanks everyday in lots of places and don't hurt themself! 
So try to be as smart as the local burger guy who just showed up yesterday??? 
And if some starts to spew out on your leg, try to move faster than a turtle. Most of us CAN do that. For starters, don't open the tank when it is not upright.
Otherwise, we just have to figure it is nature culling the flock?


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## Frank158 (Oct 1, 2013)

I think the OP was driving a car with the tank between his legs at the time of his accident. But otherwise ya, just some common sense and knowledge goes a long way. To me, the biggest danger of having a CO2 tank in the home is it tipping over by accident (dog, cat young kids) and the regulator snapping off. Now you have your very own rocket.

Keep the tank upright and secured somehow and you should be good to go with little to no worries. That and getting the tank filled at a reputable place.


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## PlantedRich (Jul 21, 2010)

Frank158 said:


> I think the OP was driving a car with the tank between his legs at the time of his accident. But otherwise ya, just some common sense and knowledge goes a long way. To me, the biggest danger of having a CO2 tank in the home is it tipping over by accident (dog, cat young kids) and the regulator snapping off. Now you have your very own rocket.
> 
> Keep the tank upright and secured somehow and you should be good to go with little to no worries. That and getting the tank filled at a reputable place.


Okay, that does put a different spin on things but not really improve my thoughts of how it happens! We have somebody who places a potential bottle rocket between his legs while driving? Sounds like a perfect setup for culling the flock or at least not letting it breed! 
Perhaps I'm being too harsh as we all tend to do silly things, at times. I like to strap the thing down in the trunk while driving! 
:grin2:


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