2x2 rule sticky/pinned

[zenmic]

Does anyone still have a copy of the 2" or 2' rule for those 13ci tanks? The old forum had it sticky/pinned. A friend was asking as they are about to buy a few of these tanks, and I wanted to point them to the sticky for reference.

[Chuck E Ducky]

Every time I have needed it I just google it. 2” round less then 2’ length (Aluminum 3k HPA tanks) are exempt from hydro. It’s on the DOT website and Most hydro pages have the info as well. Never had an issue yet in +20 years after showing the rule in black and white.

https://www.law.cornell.edu/cfr/text/49/180.209

[Grendel]

govinfo.gov link:
https://www.govinfo.gov/app/details/...80-209/context


https://www.govinfo.gov/content/pkg/CFR-2011-title49-vol3/pdf/CFR-2011-title49-vol3-sec180-209.pdf

Snap shot of relevent table out of 49 CFR 180.209:

[zenmic]

Thanks everybody!

[Nish]

Job well done.

[Frog of Peace]

I think it is silly they limited the outside Diameter.
That ist an incitation to make the walls as thin as you can to maximise capacity at the cost of security.

[lew]

Government was involved. What did you expect? Perverse incentive is their bag.

[SR_matt]

So I admit this is a bit of a necro post but I think the part you missed in your statement is as thin as possible as still meet the minimum safety factor. The tanks have to be better than a 1.66 safety factor (I.e. they are tested 66.66% above their working pressure). Thickness is pretty irrelevant as long as it meets the requirement. Just look at CF tanks from 20 years ago until now, they use probably 50% less materials.

At the end of the day someone is buying a tank for its capacity and rarely it’s outside dimensions. With the 2x2 rule the makers just extend the tank to get the volume they need since the thin profile of the tank is what allows them the exemption as it is proportionally stronger.

[Trbo323]

Question on this, aluminum tanks have no fixed life correct? So a 13/3k is good forever?

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[Grendel]

Question on this, aluminum tanks have no fixed life correct? So a 13/3k is good forever?

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This is based on US D.O.T. 49 CFR 1XX and bottles used in paintball. If you dig enough in these documents you can always find exceptions and more frustrating infinite loops that have no answer.

The short answer is no.

The longer answer is dependent upon the specific bottle and permits it is manufactured under as the original manufacturer applied for their permitting under. If the manufacturer applied for their permit under FRP-1 design testing the service life of the bottle is 15 years maximum and has to be clearly defined under their special permit (this is us typically). If they are working under ISO 11119-2 then the service life of the bottle is between 10-38 years and varies bottle to bottle (this 38 years is defined as "unlimited life" in the documents so not a literal definition but instead a bureaucratic definition). Under CFFC it is either 15 years or 30 years but 30 years requires specific administrator approval.

So one of our aluminum bottles that meets the 2x2 rules does not have to be hydrostatically tested but still has a max service life, most commonly 15years (never seen one that did not, does not mean there aren't any just never seen them). Carbon Fiber bottles have a max service life of 15 years period with no exceptions.

The table I posted in an above post is the requirements for retesting and does not include references to end of service life.

[Trbo323]

Does the 2x2 rule only pertain to aluminum cylinders?

My gut says yes but I went looking through the links in this thread and didn't see anything specifying.

I have a first strike 15/45 and all the stuff above is for DOT cert tanks. I realized I think the FS is a ISO cert. This is not my tank but here's a photo of the label on another



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[Magmoormaster]

I'm not positive but I think so. I just spent some time digging and the regulation is specific to the DOT or ISO number printed on the tank. In the case of your FS tank (I have a similar one), ISO11119-2. I googled that and the requirements shown under that specifically state a 10-38 year service life (link below, center column). Now, if I'm understanding this correctly, the 2x2 rule is only in regards to retesting, not service life. Interestingly, the ISO rating says "requalification RECOMMENDED if design life > 15 years." (CFFC-3).

It does mention that 38 years is only possible if the tank is rated to under 870 PSI. That's probably why the current Sicariis tanks are not being advertised as an "unlimited life." I wonder if they got in trouble for advertising the Hero tanks as such. Kinda stupid to make them under that rule if it doesn't extend the life of the tank though.

https://www.phmsa.dot.gov/sites/phms...astversion.pdf

EDIT: Disregard that last paragraph. I misread CFFC-3: "38 years if Ph > 60 bars (870 PSI)." Ph is test pressure and ">" means greater than 60 bars, not less than. I'm a dumb.

[William the Third]

Tank regulations are fun! So much confusion, and little to no clarification from the DOT. Does the 2"x2' rule apply only to aluminum tanks? No, nowhere does it specify what materials it applies to. DOT-3E tanks are hydro-testing exempt (don't recall what it says about service life). However, DOT-3E requires tanks be no larger than two inches in diameter, no longer than two feet in length, and made from chrome-moly steel.

Does the 2"x2' rule apply to fiber wrapped tanks? Probably not. Fiber wrapped tanks are manufactured using DOT Special Permits (DOT-SP<permit number here>), or UN ISO permits (ISO<permit number here>). Those permits specify testing and service life requirements. The DOT Special Permits used to be referred to as DOT Exemption Numbers (DOT-E<number here>), but caused confusion due to people mistakenly believing "exemption" meant "exempt" from testing/service life requirements. "Exemption" actually meant that the tank was "exempt" from any of the predefined DOT specifications (see post 3), and manufactured to its own special specification that the manufacturer paid the DOT to approve/maintain. Years ago the DOT changed from "Exemption Numbers" to "Special Permits" to clarify the confusion, and honestly, "Special Permits" is a more accurate description anyway. All DOT-E marked tanks are now retroactively DOT-SP marked tanks.

I've had "discussions" with people who still incorrectly believe that DOT-E marked tanks are "exempt" from testing/service life requirements. I know someone with a bunch of old DOT-E marked chrome-moly CO2 tanks. He doesn't use them, but keeps them because he believes that they are "exempt" from testing/service life requirements. I explained to him the above, but it still didn't register, because in his head "DOT-E" means "exempt". I then found an old fiber wrapped tank marked "DOT-E", and asked him if it too was "exempt". "No, it only applies to metal tanks" he replied. I then looked up that specific DOT-E, now DOT-SP, number, and found that it had expired. So, not only were those tanks not "exempt" from anything, they were now completely unusable. DOT-E/SP permits require regular renewals, which means paying the DOT to renew the permit. If the permit isn't renewed, then tanks manufactured under it immediately become unusable. This hit Ninja a number of years ago when a permit (SP14339 - maintained by Crossfire) they were using (or more specifically whoever manufactured tanks for them) wasn't renewed. The permit was eventually renewed, and the tanks could be used again.