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-   -   2 inch diameter rule. (

Cunha 09-06-2006 01:13 AM

2 inch diameter rule.
Ive read probably 1,000 threads on this subject, but I cant seem to remember where any are.

How does the 2 inch diameter rule work with co2 tanks? The basic rule that I remember is that any tank 2 inches or smaller in OD does not require hydro testing.

But Id like to read a real article from some dot certified source or something.

Hopefully one of you good fellas can remember where a good wealth of info on this matter can be found.

Tugboater203 09-06-2006 01:34 AM

It's 2" oe less in diameter and less then 2 feet in length. It should be stickied in the ask the experts forum with relevant dot info.


Cunha 09-06-2006 01:44 AM

Thanks bud. Its fun to be new to forums ive been posting on for years :D

So a 2 inch dia aluminum co2 tank doesnt have a lifetime either?

Rap4paintball 09-06-2006 06:23 AM

There you go:

And If you dont want to link to it:

Anything over 300psi is high pressure!... always treat it with respect!

Required Testing Cycle: 3 or 5 year? Some newer Fiber Wrapped cylinders now have a 5 year test cycle.Click Here to check for 3 or 5 year cyle. OR, drop us a note, we will check the DOT letters for you. We will need the original date and the "E" number. Click here to go to "how to read fiber wrapped bottles. We are happy to figure out the test cycle for you. Send a note with the "E-........." number and the original test date to Tank Test Cycle Check.

High Pressure Air: Sometimes called Nitro tanks (nitrogen or air). Peak tank pressure is between 3000 psi and 4500 psi. They can be steel, aluminum and aluminum/fiber wrapped.

Fiber wrapped: These are aluminum bottles, that have a fiberglass or carbon fiber wrapped around a aluminum bottle and covered with a epoxy resin. They are much lighter than regular aluminum or steel bottles. These bottles usually need to be tested every 3 years. The Newer ones may be tested every 5 years. They all have a 15 year life span. Drop us a note if you are unsure of a Tank Test Cycle.

Aluminum bottles: Plain aluminum bottles need to be tested every 5 years and have a unlimited life. A magnet will not stick to aluminum. 3AL will be stamped into the round/top part of the bottle.

Steel bottles that have 3HT stamped on them, should be tested at least every 3 years and have a life span of 24 years. A magnet will stick to one of these bottles.

CO2 tanks: 2 inches or less in diameter and less than 2 feet long, do not need to be tested. This is a DOT Rule. These CO2 bottles usually have a 1800 psi limit. Greater than 2 inches in diameter must be tested every 5 years. These bottles are not fiber wrapped. These are considered high pressure.

Proper care of your bottle includes impact prevention, never over fill beyond the certified pressure, inspect each time you fill and have a airsmith or hydro station to do a professional visual inspection inside and outside annually (the scuba guys have been doing this for 40 years). Always play safe.

FYI: Exemption Numbers That number on your tank that starts with "E-" does not mean the bottle is exempt from testing, it means the manufacturer is required to have a current authorization letter on file with the DOT. These letters describe what requirements the DOT and the manufacturers have placed on the bottle's use, the testing requirements and other important information. There are some stores and paintball web sites that say these "E" bottles are from testing. NO they are not exempt from testing, all "E" bottles must be tested (requalified).

Gumby 09-06-2006 09:11 AM

I actually have a copy printed directly off Catalina's website that I bring with me to new fields whenever I have 13ci bottles to be filled. It's listed under Tech support and then retesting of Aluminum cylinders. The exemption that they list does refer to the 2" by 2' rule but it specifies DOT-3AL being required as the stamp on these cylinders.

Here is the page info:

Catalina Cylinders
Technical Support Document

Requalification (retesting) of Aluminum Cylinders
August 22, 2005

The requalification of cylinders was formally known as the retesting of cylinders. Requalification is done to ensure that a cylinder is still acceptable to continue to be used as a pressure vessel to transport hazardous material. DOT requalifying of a cylinder and the marking thereof are to be performed by an approved DOT requalification facility that has been issued a DOT Requalifiaction Identification Number (RIN). The requirements for the requalifying of DOT cylinders in the US are identified in Title 49 of the Code Of Federal Regulations (CFR) in part 180, "Continuing Qualification and Maintenance Of Packaging" and any applicable DOT exemption.

The requalifying requirements of any cylinder are specific to the DOT specification and/or exemption to which the cylinder was manufactured. The DOT specification and/or exemption number are stamped on the crown of the cylinder. Cylinders manufactured by Catalina Cylinders are marked with "M4002" on the crown of the cylinders. Cylinders manufactured by Catalina Cylinders Cliff Impact Division are marked with "CLIFFDIV" on the crown of the cylinder.

The most basic of the retesting requirements for cylinders manufactured by Catalina Cylinders and Catalina Cylinders Cliff Impact Division are identified below.

DOT-3AL Cylinders (Catalina Cylinders and Catalina Cylinders Cliff Impact Division)

Requalifying required every five (5) years. Requalifying of a cylinder is to be performed five (5) years after the original manufacturing hydrostatic test date stamped on the crown of the cylinder. In section 180.205 (c) it states that a cylinder that is filled before the retest date may remain in service until it is emptied of its charge. In other words, a cylinder that currently has a charge when the 5 year retest date occurs does not have to be drained of its charge and retested. The charge can be used and the cylinder retested after the charge has been used.

The requalifying specified in part 180 consists of an internal inspection and hydrostatic retesting of the cylinder at a pressure equivalent to 5/3 the service pressure of the cylinder.

There are a few companies that have DOT exemptions to requalify cylinders by Ultrasonic Examination (UE) of the cylinders instead of visually inspecting and hydrostatically retesting the cylinders. In some cases there are benefits to this type of requalifying.

DOT-3AL Cylinders "2 by 2 rule" (Catalina Cylinders Cliff Impact Division only)

Requalification not required per the note under table 1 in 49CFR part 180.205. The note reads, "Any cylinder not exceeding two (2) inches in outside diameter and less than two (2) feet in length is exempt from volumetric expansion testing."

DOT-39 Cylinders (Catalina Cylinders Cliff Impact Division only)

These are non-refillable cylinders and do not require requalifying..

E-7737 (Aluminum DOT-3E) Cylinders (Catalina Cylinders Cliff Impact Division only)

Requalifying is not required.

Eddy current inspection of the threads in 6061 aluminum cylinders is not required by the DOT and is not mandated as necessary by Catalina Cylinders. Cylinders manufactured by Catalina Cylinders and Catalina Cylinders Cliff Impact Division have only been manufactured from aluminum alloy 6061, not aluminum alloy 6351, and do not require any special testing or inspection of the neck, threads or shoulder of the cylinders.

All cylinders that have been successfully requalified will have the date of the retest (month and year) stamped in the crown of the cylinder with the RIN of the DOT approved requalification facility stamped between the month and year of the retest date.

If you have any questions with regards to the requalifying of cylinders manufactured by Catalina Cylinders or Cliff Impact please do not hesitate in contacting us directly.

Catalina Cylinders - West
Corporate Headquarters
7300 Anaconda Avenue
Garden Grove, California 92841 USA
Phone: (714) 890-0999
Fax: (714) 890-1744
Email Us!

Catalina Cylinders - East
Cliff Impact Division
2400 Aluminum Avenue
Hampton, Virginia 23661 USA
Phone: (757) 896-9100
Fax: (757) 896-0206
Email Us!

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paintballmarshaltn 09-06-2006 10:17 AM

Gumby got it before me.Good job!

P4p3Rc1iP 09-06-2006 10:40 AM

Just wondering, what is the life span on small (<2"×2') CO2 cylinders?

Cunha 09-06-2006 11:58 AM

If you read above, it says that they dont have a lifetime. If one becomes damaged or starts to look physicall weak, someone may consider it unsafe and then youl want to hydro test it or just stop using it.

Gumby 09-06-2006 12:32 PM

One thing to keep in mind is that the person filling the bottle can refuse to fill it if they consider it unsafe. Don't put stickers on the bottles, they may think you are hiding damage. If this happens don't get too bent out of shape, they are not only covering their a$$ they are covering your's. If this happens just ask to speak with the manager and instead of threatening them just ask to borrow a bottle for the day instead.

Painthappy 09-06-2006 12:54 PM

^^^ What Gumby said. ^^^

They can still refuse...

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