Overfilled CO2 Tank?

[Scut_Monkey]

So I'm going to run a scenario past you guys to see what your thoughts are on this. I went to a welding supply store that is different than the one I typically go to. I had them swap out two 5# old tanks that I have been using for about 2 years for two nice shiny aluminum ones with current hydro tests as my other two were out of date. I placed both the tanks sideways with the valves obviously closed into a tupperware container in the back seat of the car. I then had to work for about 2 hours and the tanks sat in the car at 37F during that time. When I came back out to the car the lid from the tupperware container had been blown off and one of the tanks had completely emptied and froze everything around it. After I got home I tried hooking the other tank up (still full) and it kept blowing liquid CO2 into my regulators. I finally unhooked the tank and opened the valve for about 30 seconds thinking that it was overfilled. After this the tank still seems to have 6.2 pounds of CO2 in it (13.6 pounds - 7.5 pound tank tare). Now that I purged some of the CO2 off the tank seems to be working just fine and luckily my regulators seem to be alright.

Should I assume that these tanks were overfilled? I'm thinking the one tank blew it's saftey because it was simply overfilled. It's not like it was in a hot car. They were not shaking around during the drive and I know for sure the valve was closed as I would have heard it while driving. I'm lucky I was not in the car when it happened but I'm kind of upset that it seems my saftey was compromised because they sold me overfilled tanks. I called the company and they advised me to obviously bring the tank back. I'm also planning to take the still full tank back also. I'm worried about the integrity of the other tank now. At least I now know why I should drive with these in the trunk.

 

[sarsnavy05]

Placing the tanks sideways may have done the first tank in... The liquid may have triggered and frozen the safety valve and caused it to discharge the tank. A similar thing happened to me on the way home with one of my 5# tanks that was laid on its side. It was a cold day and the vehicle was cold, so the last thing that I was expecting was a) to hear an earth shattering pop in the back of my car, and b) to see my car expeditiously fill with a cloud of CO2.

It is quite possible that your tanks were overfilled, however placing liquefied gas tanks in a position other than vertical is not recommended.

 

[Scut_Monkey]

I suppose from now on I'll be transporting them upright and in the trunk. I guess I need to find a way to keep it upright though. I still wonder why the other tank seems to be 22% overfilled even after purging a lot of co2 out of it to get I working right. It makes me question the structural integrity of both tanks if they were that overfilled.

 

[outside92129]

CO2 isn't like regular compressed air (like scuba tanks) where more air means more pressure. The properties of CO2 do not pose a pressure problem at 37F even if overfilled, most of it is liquid phase and it should be at several hundred PSI. There is of course the issue with the safety value getting frozen over with a higher than expected fill (or tilted) tank. So tanks themselves should be fine.

 

[Scut_Monkey]

CO2 isn't like regular compressed air (like scuba tanks) where more air means more pressure. The properties of CO2 do not pose a pressure problem at 37F even if overfilled, most of it is liquid phase and it should be at several hundred PSI. There is of course the issue with the safety value getting frozen over with a higher than expected fill (or tilted) tank. So tanks themselves should be fine.

So should I assume the tank that is still full but overfilled is still structurally sound?

Edit: I see you answered that. Sometimes I miss things browsing on my phone. I'll most likely be dropping the other tank off tomorrow and I'll see what they say about it.

 

[Scut_Monkey]

So I returned the tank that blew. The guy just swapped it out for another tank after hearing what happened. I have yet to weigh this new tank but based on what I've seen so far it appears that they overfill them. That worries me as one of the tanks I store at about 45 degrees for my mobile tank setup. Not sure what to do now.

 

[Scut_Monkey]

Ok so the new tank is coming in with a fill weight of 7 pounds co2 (14.6 pounds total - 7.6 pound Tare weight. Is it common to fill a tank with 40% more co2 than its rated for? It's nice when you get extra product than what you paid for but i dont think this is a good example of that. Am I missing something?

 

[outside92129]

Um... it's a good deal? I wouldn't worry too much about it, the tanks are tested at 3000psi every 5 years, the burst disks are set for someplace between 1800-2500psi, and with the phase change of CO2 you're only holding the gas at 750-1000psi. I wouldn't drive it to Palm Springs in the summertime, but that would also be a bad thing to do with a normal fill. Of course you said you want to use the tank at a 45.... you definitely do not want to extract liquid CO2 from the tank, that could make a mess of your regulator. You should have it vertical, why is it at 45? (O2 and argon tanks are ok lying down, CO2 and acetylene... no bueno)

You did get me curious as to my fill at the local welding shop. The next time i get a fill i'll measure it and get back to you about what i've been getting. I figure i'm 1/2 to getting a fill.

 

[Scut_Monkey]

Well it's good to know that it shouldn't pose a danger. I like to keep the tank at a 45 degree angle as I store a tank in tool carrier for my mobile keg setup. I guess I'll have to change this. Until now I had no idea that these tanks needed to be stored upright and I have been getting away with it fine for two years even with full tanks from my previous supplier. I guess I should wonder if I was even getting a 5 pound fill from the previous guy. Thanks for the help.

 

[SBC]

bungy strap your bottle in a milk crate for transportation

 

[outside92129]

Having a tank temporarily at a 45 or horizontal isn't an issue as long as it's not being used. I lie mine down so they don't roll around when getting a swap. But before use put it in vertical position, maybe for an hour or two to be safe, before cracking the valve.

 

[anthonyws]

Um... it's a good deal? I wouldn't worry too much about it, the tanks are tested at 3000psi every 5 years, the burst disks are set for someplace between 1800-2500psi, and with the phase change of CO2 you're only holding the gas at 750-1000psi. I wouldn't drive it to Palm Springs in the summertime, but that would also be a bad thing to do with a normal fill. Of course you said you want to use the tank at a 45.... you definitely do not want to extract liquid CO2 from the tank, that could make a mess of your regulator. You should have it vertical, why is it at 45? (O2 and argon tanks are ok lying down, CO2 and acetylene... no bueno)

You did get me curious as to my fill at the local welding shop. The next time i get a fill i'll measure it and get back to you about what i've been getting. I figure i'm 1/2 to getting a fill.

Don't forget about hydraulic expansion of the liquid. It is not the gas pressure that over pressures the cylinder. This is why they are never filled past 68% by weight. I believe the density of the liquid is near the density of water so you can quickly calculate the fill from 0.68x the water capacity(in lbs)