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RE: [PSUBS-MAILIST] old SCUBA cylinder
I was teaching SCUBA at the YMCA during this period. The cylinders were
under ICC (Interstate Commerce Commission) and required the necks of the
tanks( which were steel) be identified as to rated pressure. The regulating
agency now is the Department of Transportation (DOT). Requirements for hydro
was once every 5 years to a test pressure of 5/3 times the rated pressure.
Expansion was measured with the criteria that volume had to return to within
10% of the original volume after the test pressure was applied. All tanks
were stamped on the neck as to hydro dates along with an identifying mark
for the testing facility and sometimes included a + mark indicating that
during the first 5 years could be charged to a 10% overload..
If the tanks you have don't have stamped marking on the neck I would suspect
too much paint. You might try a wore wheel to remove the paint. Without the
legible stamped markings no one would test even though the testing was safe
due to using water to fill the tank for testing. The 3AA indicates chrome
moly steel rated at a working pressure of 2400 PSIg. Most tanks at this time
were rated at 2250 PSIg. I also had some of those surplus O2 tanks with the
wire wrapping which I removed. I think they would contain 38 cubic feet.
My information and experience dates from this time, mid to late 60s. I'm a
little older than 18.
Some of my tanks did fail hydro, by cutting the bottom off I made them into
bells. Turned out nice.
Hope this helps a little.
Ken Martindale
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Jim Rudholm
Sent: Friday, February 10, 2012 5:44 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] old SCUBA cylinder
I started SCUBA diving in the fall of 1959. Our area, central
California, had a fire extinguisher company that pressure tested and
certified industrial cylinders and SCUBA tanks. My first new tanks
were a pair of steel Kidde 72s, marked ICC3AA2400. Our local dive shop
would only go to 2250psi for a refill. We had some CO2 1800psi tanks
from military surplus that were wire wrapped to make them
shatterproof. This wrapping had to come off for a hydo test. Later in
my shop there was a tall oxygen cylinder with a first test stamp date
of 1914!
JimR
On Fri, Feb 10, 2012 at 1:17 PM, Sean T. Stevenson <cast55@telus.net> wrote:
> I think that most dive shops do not perform their own cylinder testing,
but
> rather subcontract that service to companies which specialize in testing
of
> not only SCUBA, but SCBA, fire protection and industrial gas cylinders.
In
> North America, cyclinders are certified according to Transport Canada
and/or
> US Department of Transport regulations. and the hydrostatic testers use
the
> stamp information to determine what standard to test to. I don't know
> whether the apparent absence of markings is due to this tank being so old
> that it predates the regulatory framework, or whether they are under there
> under a very thick coating of paint. I doubt the former, but can anyone
who
> was diving in the early 1970's verify this?
>
> -Sean
>
>
> On 2012-02-10 05:53, Smyth, Alec wrote:
>>
>> It depends where you are. When I lived in Argentina, the answer was yes,
>> the tank would be hydroed, almost certainly found to be just fine, and
>> enjoyed so long as it continued to pass its tests. Here in the States, I
>> have four such tanks in my garage but the local dive stores refuse to
>> even test them, although they ring clear as a bell when tapped (meaning
>> they likely have no rust).
>>
>> Alec
>>
>>
>>
>>
>>
>> From: owner-personal_submersibles@psubs.org
>> [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Sean T.
>> Stevenson
>> Sent: Thursday, February 09, 2012 11:47 PM
>> To: personal_submersibles@psubs.org
>> Subject: [PSUBS-MAILIST] old SCUBA cylinder
>>
>> While cleaning out the garage, I came across an old SCUBA cylinder, with
>> no apparent tank neck markings. It does have a thick yellow paint job,
>> so it's possible that there are stamps which are covered, but I didn't
>> see any evidence of such marks on the neck. The cylinder has a visual
>> inspection sticker on it which is dated April 1972. I just bled the air
>> off but apparently it was full (!) Does anyone know if the cylinder can
>> be salvaged / recertified for any purpose, or is it destined for
>> recycling?
>>
>> -Sean
>>
>
>
>
>
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