CO2 Tank Burst Disks

[Toestr]

So I recently got 2 CO2 tanks with 3K burst disks on the valves, but both tanks are stamped 1800. They are both fairly new tanks (2011 is the oldest) and I have no reason to believe they've been tampered with. Should I be concerned?

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[Jordan]

CO2 tanks have been using 3k burst discs for a long time now.

[Toestr]

CO2 tanks have been using 3k burst discs for a long time now.

Yes I just expected them to be on a 3k tank.

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[Jordan]

Yes I just expected them to be on a 3k tank.

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Co2 tanks have always been rated for 1800psi... I know, it doesn't make sense that they have 3k burst disc's, but they've had them for over a decade now. No idea why they switched over.

[Mechstar]

I change mine back to 1800 when I buy a new valve or receive an old tank.
Probably overkill…and a weakened disk will occasionally pop off in a hot garage or car…but I still prefer that way. Even though I fill my own tanks mostly.

Even though the actual failure pressure on the tank SHOULD be much higher than the stamped certification on it, my brain says that with a 3k burst disk, I am basically putting a 1800 psi “burst tank” onto a 3k micro “vessel” LOL.

I will defer to the experts if I am being paranoid.

[SignOfZeta]

I’m NOT an expert. My guess…

The tank is rated for 1800psi of USE, which is to say that it won’t blow at 1801psi. That’s it’s operating range, not the point at which it pops.

The disk is rated to FAIL at 3000psi, which would be less than twice the pressure of the tanks normal use range, which seems like a good place to blow.

[ChoSanJuan]

I’m NOT an expert. My guess…

The tank is rated for 1800psi of USE, which is to say that it won’t blow at 1801psi. That’s it’s operating range, not the point at which it pops.

The disk is rated to FAIL at 3000psi, which would be less than twice the pressure of the tanks normal use range, which seems like a good place to blow.

I'd say this is something similar to how hyrdo tests work (primarily) for HPA... They keep your 2 original burst disks - 1.8k for reg output and 5k-7.5k for the tank - then they fill it to like 6k under water to see if it blows. That's part of the operating pressure part of things. Of course you don't want to die at a fill station when you hit 4501psi and, let's face it, how much are you trusting an analog gauge that gets beat up every time you hit the field? (Anyone still running AngelAir? )

[Toestr]

I’m NOT an expert. My guess…

The tank is rated for 1800psi of USE, which is to say that it won’t blow at 1801psi. That’s it’s operating range, not the point at which it pops.

The disk is rated to FAIL at 3000psi, which would be less than twice the pressure of the tanks normal use range, which seems like a good place to blow.

That explanation makes sense. The idea doesn't though. If normal operating pressure is 800psi then getting to 3k would require some extraordinary circumstances. 1800psi is a far more plausible pressure to reach (ie hot car), but would still be beyond what would be normal. Considering the tank pressure is also output pressure I think I'd like it to burst at 1800 rather than 3k.

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[SignOfZeta]

That explanation makes sense. The idea doesn't though. If normal operating pressure is 800psi then getting to 3k would require some extraordinary circumstances. 1800psi is a far more plausible pressure to reach (ie hot car), but would still be beyond what would be normal. Considering the tank pressure is also output pressure I think I'd like it to burst at 1800 rather than 3k.

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I can see what you are saying but these rules weren’t made for paintball. They are rules that apply to lots of compressed cylinders. Your gun probably won’t even fire at 1800psi because there is a couple hundred pounds holding the valve closed at that point. The burst disc is to prevent the tank from rupturing, it has nothing to do with paintball performance in any way. It’s not meant to prevent hot rounds, and it won’t.

[Toestr]

I can see what you are saying but these rules weren’t made for paintball. They are rules that apply to lots of compressed cylinders. Your gun probably won’t even fire at 1800psi because there is a couple hundred pounds holding the valve closed at that point. The burst disc is to prevent the tank from rupturing, it has nothing to do with paintball performance in any way. It’s not meant to prevent hot rounds, and it won’t.

I'm more concerned with hoses, fittings and any other air passages rupturing.

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[dhaupin]

You can put an 1800psi disk in your c02 tank valve if you like. In my experience in the before times, I've never had 1800 burst/fail unless it was at a filling station.

Maybe that's why they changed it (to counter a higher spike of psi whilst filling?)

[DocsMachine]

Okay, technically a CO2 tank is rated at 1800 psi. Yes, the usual operating pressure is 800-900 psi, but the tank is rated for 1800.

Point in fact: The very first 'screw in' HPA regs were meant to install on 20-ounce tanks, giving a field that had a supply of 20s, an inexpensive way to upgrade to HPA. 1800 psi in a 20-ounce tank, is more than enough to run a typical rental for about 200-250 shots.

Anyway, if you're running CO2 in the tank, then an 1800 psi disc is more than adequate. A 3K disc is legal, as it's nominally half-again what the tank is rated for, but as noted, an 1800 tends to give you a little more protection.

A burst disc is supposed to be rated for 1-1/2 times the rating of a tank- that's why a 3K tank has a 4.5K disc, and a 4500 usually has a 7 or 7.5K disc.

Doc.

[un2xs]

My former boss used to hydro CO2 fire extinguishers. He told me that all extinguisher cylinders were hydro tested at three times the rated pressure. I imagine this is an industry standard for all pressure vessels.

[DocsMachine]

Pretty sure it's 1-1/2 times the rated pressure, though for a CO2 tank, that would be more or less three times the operating pressure.

If it were three times, that means we'd be testing 4500 tanks to 13,500 psi, and I'm pretty sure they don't do that.

Doc.

[Hp_lovecraft]

What I was always told was the industry moved from 1800psi to 3000psi because we "paintballers" are not good with our equipment, and all the tanks blowing the discs on a hot day, and often being returned, was a burden for the retail industry. "An 1800psi co2 tank should never "blow" if stored properly. "

That is what I was told, and having working at many fields in the early 90s, many, many tanks would blow.

To answer the original question, 1800psi co2 tanks are not the same as 3000psi tanks. The 3000psi tanks are thicker with more threads. That said, 1800psi is not a "burst" rating. It is the service limit. It is the max pressure that the tank would normally expect to service. Should you put the 3000 disc on the 1800psi tank?

No, But we did worst things back in the day. It wasnt uncommon for people to "double up" 1800 discs to keep them from blowing. And blown discs were so common, and annoying that fields everywhere started underfilling tanks. Even after the switch to 3000psi tanks. Its hard to get a full fill anywhere.

And the reason for the high pressure limits is metal fatigue. Thermo cycles, over filling, and general rough handling all contribute to an actual lower pressure limit. But there is no way to know what that limit without hydfotesting. Thats why the limit is so far forward