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Old 08-08-2008, 12:22 AM   #11 (permalink)
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Originally Posted by Yomama101 View Post
Bottles 2 inches in diameter or less, and less than 2 feet long DO NOT have to be tested.
"The 2 and 2 rule."

Requalification (HYDROTESTING) 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."

This only applies to DOT 3 AL tanks only! read the rules and the section it is under!
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Old 08-08-2008, 01:15 AM   #12 (permalink)
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We have many 3.5 oz. tanks and have had them for years and have never had one fail. We had two 4 oz. Brass Eagle tanks. Both are currently lying in my basements with 1.5" long splits in the tanks where they blew up. Both blew up on different days (one narrowly missing my head) and blew before the stock burst discs blew. Needless to say, I will never own another one and if I have to fill one, I under fill it by a good margin (at least an ounce).
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Old 08-08-2008, 10:25 AM   #13 (permalink)
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This only applies to DOT 3 AL tanks only! read the rules and the section it is under!
I think the 2x2 rules applies to all DOT-3 series and DOT-4 series tanks, which for us generally only applies to aluminium tanks.

Does anyone know what the DOT code is for the BE 4oz tanks?
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Old 08-08-2008, 05:40 PM   #14 (permalink)
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I got two BE tanks right here.

DOT-3E1800 M9001 10^99 J47
DOT-3E1800 M9001 10^99 J6

Both tanks are only 3 thousandths larger then 2" which would leave me to believe that they are exempt. One thing that I can't believe is that the tank is rated for 1800 as per the stamp they have 3k bursts disk in the valves. Can someone else agree that this is a bad idea? If Brass Eagle screwed up then I'm going to have to discard the tanks since they could of been overpressurized. Either way I'm getting some 3.5 tanks in the near future.
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Old 08-08-2008, 05:46 PM   #15 (permalink)
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Mike, they aren't aluminum, so they aren't exempt. Hence, DOT 3 AL. It makes sense - Aluminum tanks can be expected to survive without internal corrosion, while you would have to retest steel tanks to find out if there is damage beyond what can be seen externally.
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Old 08-09-2008, 02:11 PM   #16 (permalink)
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I'm glad i was pointed in the direction of this forum, because some of you people are bassackwards.

The wonderful -2"x2'- rule: Any cylinder not exceeding 2 inches outside diameter and less than 2 feet in length is excepted from volumetric expansion test. NOTE: 49 CFR 180.209 does not say ONLY tanks adhering to this rule are exempt. It says tanks that meet the 2 x 2 rule are INCLUDED in the exemption from requiring retest. 3E tanks commonly exceed these dimensions.

DOT 3E series tanks can only be chrome-moly steel unless they have an exemption number/special permit number stating they are aluminum.

The burst disc of a tank is rated to the TEST PRESSURE of the tank, which is x-times the working pressure stamped on the tank. If the tank is stamped as 1800psi wp, the burst disc is 3000psi for 3AL and 3E tanks (5/3 pressure rating).

ModestMike's tanks are exempt from testing, and just fine to use.


I am a little shocked at Nick making this mistake:
Quote:
Anyway, avoid the 4oz tanks. They are not exempt from hydro because they are steel...
this is flat wrong.

ANy tank stamped 3E IS EXEMPT FROM TESTING UNLESS IT HAS AN EXEMPTION NUMBER SPECIFIED, AND THAT EXEMPTION IS NO LONGER VALID.

B: 49CFR part 180.205 has to do with General requirements for requalification of cylinders.

49CFR part 180.209 is Requirements for requalification of specification cylinders.

DOT3 series tanks include:
3A,AA - Steel
3AL - Aluminum
3AX, 3AAX - Steel
3B, 3BN - Nickel
3E - Chrome-Moly Steel (unless otherwise specified by exemption)
3HT - Steel
3T - Steel
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Old 08-09-2008, 02:25 PM   #17 (permalink)
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A better statement would be "avoid the steel tanks because they are not reliable"

Ive seen some exploded steel tanks too. No exploded aluminum tanks.

Gee wis. At least they dont fragment. The ones Ive seen anyways.
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Old 08-09-2008, 02:38 PM   #18 (permalink)
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A better statement would be "avoid the steel tanks because they are not reliable"

Ive seen some exploded steel tanks too. No exploded aluminum tanks.

Gee wis. At least they dont fragment. The ones Ive seen anyways.
The two that exploded on me just split open and flew across the room at fairly high velocity. They could definitely knock you out or seriously harm you if they hit you in the right (wrong) part of the body. Fragmentation and shrapnel would be much worse.

I do find this part interesting..."The burst disc of a tank is rated to the TEST PRESSURE of the tank, which is x-times the working pressure stamped on the tank. If the tank is stamped as 1800psi wp, the burst disc is 3000psi for 3AL and 3E tanks (5/3 pressure rating)." Why would the burst disc be rated for the same pressure it is tested to? Wouldn't you want the burst disc to blow before the tank fails (which did not happen in the two that I owned and blew up on me)? Unless a 3,000 psi burst disc is actually designed to blow below 3,000 psi and is just called 3,000 psi by name???
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Old 08-09-2008, 02:42 PM   #19 (permalink)
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Burst discs are rated at the test pressure but require to fail/blow in a range of -20% / +0%.

EDIT: generally when burst discs fail at pressures way under that rating, it's because the metal discs inside the nut have been weakened over time.
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Old 08-09-2008, 03:21 PM   #20 (permalink)
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Quote:
Originally Posted by Cunha View Post
A better statement would be "avoid the steel tanks because they are not reliable"

Ive seen some exploded steel tanks too. No exploded aluminum tanks.

Gee wis. At least they dont fragment. The ones Ive seen anyways.
I agree, I've heard some horror stories about those steel ones. I tried to tell the folks on butter world about that before...bad idea...

Also, aren't the steel tanks over 2" OD?
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