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My Co2 tank blew off!

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bja

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I had my 5 lb. co2 tank refilled yesterday. When I was walking out of the store, I thought that it felt heavier than normal. Got home and set the bottle on the floor beside my kegerator. The outside of it was still frozen. Three hours later the relief valve blew off. Filled the room with fog. Is it possible to over fill a co2 tank?
 

Fingers

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Of course it is. I'll bet they put 10 pounds instead of 5 in there. Check the outside rim of the bottle for tare weight. It my be abbreviated as TW and then a number, usually in pounds. That's how much your tank weighs empty. Weigh your tank and the amount over the tare weight is the remaining CO2. If it's anywhere near 5 pounds you were definitely over filled.

When your tank is cold the pressure inside is much lower than when it's warm. That's why it didn't blow when it was filled. As it warmed the pressure climbed from around 500 psi to over 800 psi. When your relief valve triggered it vented to a safer pressure which could, and likely is, less than the warm 800 psi pressure so the above test may not tell you much but it would be interesting to see. If you do it, please let us know the results.

If it were me, I'd take the tank back to the refilling station and let them know what happened. It may be an isolated incident or it may be an employee that is not properly trained. Either way, if it's a faulty valve or a faulty fill, the cause should be determined and corrected before someone gets hurt.
 

david_42

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Any time a CO2 tank is "filled", some head space must be left because liquid CO2 expands a lot near room temperature. Take the tank back and explain what happened. They might have to replace the relief valve as some of them are single use.
 
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bja

bja

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Just got back from the refilling station. They told me that it's "difficult" to over fill them, but they didn't say it couldn't be done. Without admitting any fault, they finally agreed to replace the relief valve (it is single use) and refill at no charge. Problem is they need to order the valve and it'll take a few days. Luckily I have a spare tank.
 

malkore

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just be glad it didn't blow the valve in your car coming home. you could have very easily been suffocated, or at least lost consciousness.

its only difficult to overfill them if someone isn't paying attention. even 6lbs in a 5lb cylinder could pop the valve once it warmed up.
 

Fingers

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My son fills paint ball tanks and it is sometimes hard to get the required amount in them. You have to cool them or purge a few ounces to cool the tank enough to get the gas in. He filled my 5 pounder for me and said he had no problem putting the 5 pounds in. He clearly could have overfilled it if he hadn't been paying attention.
 
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bja

bja

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malkore said:
just be glad it didn't blow the valve in your car coming home. you could have very easily been suffocated, or at least lost consciousness.
I've read about this happening to someone once. It filled the car up with fog and he couldn't see where he was going. Luckily he got stopped and out of the car without any injuries.
 

HP_Lovecraft

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Having worked at many paintball fields, it is easy to do.

Co2 is a "self regulating gas", meaning the liquid in the tank adjusts to keep the pressure equalized to around 800psi, regardless of how much liquid is in the tank. So a full tank is 800psi, and a near empty tank is 800psi.

The only catch is the tank needs at least 25% "headspace" in order to properly equalize, or the pressure skyrockets up to 2000-4000psi.

So that 5lb tank could actually hold 7lbs if the headspace was accidentally filled, which is possible if the filler was not paying attention.

Vents are usually rated 1800, or 3000 (depending on application, and tank material). If the vent blew, it can only mean the tank was overfilled (or defective).

nick
 

Fingers

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HP_Lovecraft said:
Having worked at many paintball fields, it is easy to do.

Co2 is a "self regulating gas", meaning the liquid in the tank adjusts to keep the pressure equalized to around 800psi, regardless of how much liquid is in the tank. So a full tank is 800psi, and a near empty tank is 800psi.

The only catch is the tank needs at least 25% "headspace" in order to properly equalize, or the pressure skyrockets up to 2000-4000psi.

So that 5lb tank could actually hold 7lbs if the headspace was accidentally filled, which is possible if the filler was not paying attention.

Vents are usually rated 1800, or 3000 (depending on application, and tank material). If the vent blew, it can only mean the tank was overfilled (or defective).

nick
But wouldn't that require the filler tank to be above 800 psi?
 

wihophead

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Fingers said:
But wouldn't that require the filler tank to be above 800 psi?
I believe they chill the receiving tank by adding a small amount of CO2 then bleeding it off.
This lowers the receiving tank pressure allowing it to take an entire fill.
 

HP_Lovecraft

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That is the thermal variance method.

Other places might use co2 pumps, or boosters which would not require the target and source to be different pressures.

nick
 

Fingers

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HP_Lovecraft said:
That is the thermal variance method.

Other places might use co2 pumps, or boosters which would not require the target and source to be different pressures.

nick
That makes more sense to me. Sort of like what they do with propane. I can see pumping liquid into a tank being more effecient and quicker but also more likely to cause what the OP experienced.
 
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Because of suffocation danger in case of an accident and/or relief valve activation, the welding shop that fills my tanks won't even sell gas to you if they know you plan on transporting the tank inside the passenger compartment.

There's enough gas in any full tank to easily fill a large room with CO2. Glad you didn't get hurt!
 
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bja

bja

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Yuri_Rage said:
Because of suffocation danger in case of an accident and/or relief valve activation, the welding shop that fills my tanks won't even sell gas to you if they know you plan on transporting the tank inside the passenger compartment.

There's enough gas in any full tank to easily fill a large room with CO2. Glad you didn't get hurt!
No one got hurt but it scared the crap out of my dog, she was shaking for a half hour. The bottle ended up against my 90 gallon reef aquarium, about 10 feet away from where I put it. I'm not sure how much it was flying around but I'm lucky it didn't hit the glass.

I knew something wasn't right when I left the store because it felt heavier than normal, but I will be transporting this thing in the trunk from now on.
 
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