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PST made some oddball 3000 steel 3AAAs some years back which were about the size of a 72 but thicker walled and, as a result much heavier. They were claimed to hold 80 cf, but whether that was with the "+" or not I cannot recall offhand. But that would sound like what you have. Perfectly...

Never gets a mention? My impression is it gets discussed incessantly. The CFR only applies to tanks in commercial service. Privately owned cylinders not being used in commerce are not covered, so the owner (or a diveshop, acting on the owner behalf, is free to overfill it . That doesn't make...

CGA "rules" are NOT necessarily referenced into the CFRs. SOME CGA publications are. There's a list of which ones at the beginning of 49 CFR, at 171 or thereabouts. Last thing I knew, P-5 was not one of them, so (unless things have changed) it is only advice, not law, and does not empower anyone...

The only "official" definition is the DOT's, which says HP is 900 psi or over. I personally draw the line at 3300 psi, since it puts the oddball "slightly over 3000" short-fill specials like the compact 80s and 71.4 Faber/Scubapros in the lower category, where they belong, but groups the 3442...

Sorry about that. We use a contact form on the website rather than an email, to make it harder for spammers to find our email, and we recently found that some of the contact form links on certain pages hadn't hadn't been working for who knows how long because of changes at our ISP. That's been...

The tanks cease being DOT legal the minute the exemption expires, regardless of hydro status. so a last minute hydrotest is no guaranty of another 5 years. Though I suspect that many shops will go on filling them regardless of exemption status as long as the hydros are good, so it may be...

A little more info, like pressure and other markings would be useful. PST is said to have made some 3300 psi 72s that were 6.9" or so, and about 21" long. Also there are a lot of industrial tanks that occasionally get misrepresented as scuba. The 72s mentioned above would have been...

The general feeling (though it is far from unaminous) is that the neck O-ring should NOT be lubed, since it is static and doesn't need lubing, and anyhow is not really acting as an O-ring at all but rather as a crush seal. Lube will just encourage it to extrude. The threads, though, should be...

An oddity of the new regulations is that while the eddy test and VE stamp are mandatory only for the older 6351 alloy tanks, and the newer 6061 alloy tanks don't have to have it, a hydro shop is allowed to eddy test the newer tanks if they feel like it, or the customer requests it, and if the...

Actually, when you do two tests in a row on a steel tank, the first test ends up acting as the "prestress" cycle for the 2nd one, increasing the odds that it will pass the 2nd one. So the results of the second test prove nothing about the first. Measuring expansion is not a repeatable...

PST made some tanks back then that were about the same size as a steel 72, rated for 3000 psi, and held a tad less than 100 cf at 3300 psi (3000 psi plus 10% + overfil), and this sounds like what you've got. Perfectly respectable tanks, though they had a reputation for being heavy, possibly...

Nylon is hygroscopic - it actually absorbs and holds water. Add a little salt (and once salt gets in webbing no amount of rinsing will ever get it completely out) and it can suck the moisture right out of the air, so it remains damp even when the rest of the tank isn't. I sure wouldn't use it...

Or just flush the tank out with scuba air, which is very, very dry, immediately before valving. Easy to do by undoing the first stage of a regulator from its hose and sticking the hose end in the tank.

Hardly any. For moisture to accumate the tank has to be cooler than the ambient temperature (so it condenses water from the air) and enough air has to circulate through the tank to bring in a troublesome amount of moisture. But the hole in the tank is small, so air exchange happens slowly and...

You will note I said "supposed to be" not "are"! What kind of a failure rate are you seeing on these tanks? The current explanation that I have been hearing is that the zinc coating (and the mixed zinc/steel layer several thou thick that froms between the zinc layer and the steel) is less...

The story I am hearing is that Worthington has found hot dipping tanks a lot fussier than they had anticipated (Worthington wasn't doing galvanized until they started making scuba tanks in 2005 or so), and the process has required some fine tuning. Current tanks are supposed to be OK, but the...

What is TDI teaching its visual inspectors? Even if they are not teaching O2 cleaning , I'd think this is a common inspection/stickering question that should have been covered in class. considering especially that combo visual/02 clean sticker are in general use now. To answer the question...

Actually, SP listed the "71.4 Slim" as they called them, as being 6.84" OD.

Do you mean visualled or hydroed? Hydros are done every 5 years, so changing the date won't help water in the tank much, not at least, 4 years out of five. Scheduling yearly visuals for just after your live aboard trips might help, if only by giving the tanks a bit of a chance to dry out. But...

I would worry about trying to run such a large and complex rig while also herding students about. Will you have someone competent assigned to just filling tanks and keeping an eye on the system or will you be doing this yourself along with tending to the students? One is reminded of stories...