What do the numbers on scuba tanks mean?

[broncobowsher]

Slight revision, Steel cylinder are regularly overfilled in Florida. Outside of Florida you don't regularly find places doing "cave fills" .

TP = Test Pressure. It is the pressure that the cylinder should be tested at when doing a hydro. This is where you can run into issues with a shop botching a hydro. If they ignore the TP and go with the 5/3s working pressure they exceeded the test pressure and will probably condemn what was a good tank. So you need to watch it when it comes time for a hydro. Avoid bad testers.

 

[Divin'Papaw]

Your test pressure is 5/3 of working pressure. Our test pressure is 150% of working pressure. My old 200 bar tank would, if it passed a 300 bar hydro, only be certified to 180 bar on the left side of the pond.

While I wouldn't have any issues regularly "overfilling" that tank by 10% by your rules, I'd be more reluctant to fill it significantly beyond 200 bar (cold).

What's this Bar that you speak of?

 

[Storker]

@Storker - yeah, that is a head scratcher. The requalification test standard, IIRC, is 5/3 working.

No idea if there is another "new" standard...

I guess they've just stamped Euro test pressure on the neck. Whether you guys ought to hydro it to 5735 or limit your fills to 3150, that's up to you. Since our test pressure is 150% of working pressure, I'd be just fine filling that tank to 3442 psi or 232 bar if it had passed a 5750 psi/400 bar hydro test.

 

[Divin'Papaw]

Slight revision, Steel cylinder are regularly overfilled in Florida. Outside of Florida you don't regularly find places doing "cave fills" .

I've always considered a "cave fill" being the HP filling (3600+) of LP tanks. Filling a HP tank to 3700-4000 I don't (personally) consider a cave fill. I rather consider it good customer service.

 

[Angelo Farina]

As the test pressure of 5250 PS is written after the REE100, it means that is the test pressure following that procedure.
This is a tank built for Americans here in Italy.
If it had been built for being tested according to EU regulations, the working pressure and testing pressure (which is 150% the working pressure) had been written in bars, not in PSI...

 

[Storker]

What's this Bar that you speak of?

10000 Pa, or roughly 14.7 of your psis. And it's "bar", not "Bar"

Bar (unit) - Wikipedia

 

[Divin'Papaw]

10000 Pa, or roughly 14.7 of your psis. And it's "bar", not "Bar"

Bar (unit) - Wikipedia

... or is it BAR??

I know what it is BTW. I just don't speak metric. I prefer our confusing, complicated imperial units. Metric is too easy and makes too much sense.

 

[NorCalDM]

The test pressure is based off the design pressure not the working pressure and the working pressure is usually lower than the design pressure. So typical ASME codes for pressure piping and vessels which in the US this falls under are hyrdo tested to 1.5 times the design pressure. I would think the test pressure is based off a 3500 psi design pressure whcih works out to 5250 psi test pressure.

 

[Divin'Papaw]

The test pressure is based off the design pressure not the working pressure and the working pressure is usually lower than the design pressure. So typical ASME codes for pressure piping and vessels which in the US this falls under are hyrdo tested to 1.5 times the design pressure. I would think the test pressure is based off a 3500 psi design pressure whcih works out to 5250 psi test pressure.

That makes some sense ... except for where does 3442 come from? I always wondered that. Seems so random.

 

[Storker]

That makes some sense ... except for where does 3442 come from? I always wondered that. Seems so random.

Here on the right (pun definitely intended) side of the pond, standard tank pressures are 200, 232 and 300 bar. 200 bar is archaic, I don't think you'll find a new steel tank rated below 232 bar these days.

200 bar = 2900 psi, 3000 psi = 207 bar, close enough for government work.
232 bar = 3365 psi, 3442 psi = 237 bar, close enough for government work.
300 bar = 4350 psi

I have no frikkin' idea why y'all chose 3442 instead of, say, 3400 psi.