Question ID these?

[Scared Silly]

It's full when it is filled to working pressure; which in this case is 2400 psi. The nominal capacity is at the 10 percent overfill pressure but that's just marketing.

Call it whatever you want. The point is that the nominal capacity (e.g. 85 cu ft) is reach when filled to 2640 psi and is thus is "full." Many people do not understand that fact about cylinders with a plus rating. When there is not plus rating and the working pressure is 2400 psi one does not get a "full" fill, but the nominal capacity less 10%. (e.g. 76.5 cu ft vs 85 cu ft).

 

[Couv]

I love when people present a poor scan of a 52 year old document to me so they can get a plus rating on an old tank. Especially when it is a steel 72, and that line has a misprint on the pressure rating.

@Tracy OK Fair enough. I'm not a re-tester, so now you'll have to educate me. I have presented that poor old scan to a re-tester. While he agreed there was a misprint on it (just as you said on the 7.12 foot line) he explained it was easy enough for him to interpret-and besides, he knew the math and had done the measurements to confirm the REE was correct. Again, all Greek to me. Are you saying that is not possible? What would you tell a customer who wanted the plus rating on a PST 72?

Re the REE: If the OP's tank has the REE stamped on it, can that not be used to determine the test required to apply/not apply the + rating. If the tank does not have the REE number on it, is there a similar document that list the REE? What would you tell the OP? `

Inquiring minds want to know.

TIA

 

[Tracy]

@Tracy OK Fair enough. I'm not a re-tester, so now you'll have to educate me. I have presented that poor old scan to a re-tester. While he agreed there was a misprint on it (just as you said on the 7.12 foot line) he explained it was easy enough for him to interpret-and besides, he knew the math and had done the measurements to confirm the REE was correct. Again, all Greek to me. Are you saying that is not possible? What would you tell a customer who wanted the plus rating on a PST 72?

Re the REE: If the OP's tank has the REE stamped on it, can that not be used to determine the test required to apply/not apply the + rating. If the tank does not have the REE number on it, is there a similar document that list the REE? What would you tell the OP? `

Inquiring minds want to know.

TIA

While he is correct, it is very easy to determine it is a misprint. He has no legal documentation for the REE of that tank. A misprint is wrong information, even if accidental. Nowadays, we would consult the manufacturer and have them either e-mail an updated sheet or confirm that it is indeed a misprint. That leaves a paper trail and shows due diligence if it ever was pressed legally. This isn't an option with any steel 72s, all of the manufacturers are out of business.
You can do the math and calculate your own REE, that is perfectly acceptable. If the tester believes your calculations and is comfortable using them, that is fine, I would not. They can calculate it themselves, but it comes down to time versus money. Spend 20 minutes calculating an REE to place an arbitrary stamp on an antique tank. It isn't worth the time. The stamp changes nothing in the real world. Steel 72s typically get filled to 3k same as all of the other tanks in line.
I would and do tell the customer exactly that. None of my customers have ever cared as the tanks get filled the same regardless of a plus stamp.
Most if not all modern tanks have the REE stamped in the neck, this was done to expedite hydro procedures, it is easier to look at the tank while you are already there getting a serial number than it is to look up specs in a book.
Scuba bottles aren't some magical bottle, they are the same as every other industrial bottle that all get hooked together and filled simultaneously to the same pressure. They don't sort industrial bottles by hydro plus stamps and fill them separately. People get all hyped up about minutiae that in the end just doesn't matter.

As a side note. A scuba facility that does in house hydros is a different case. It would be worth their time to figure out the numbers for different manufacturers and keep them on hand. It is a small world and they will continue to see the same type of tanks over and over again. To a large industrial retester doing hundreds of hydros every day, scuba is such a small tiny aspect of their business, it just doesn't make sense.

 

[Couv]

@Tracy Thank you for that. Just to clarify, don't all PST 72s have the same REE? Basically, once the REE has been determined, don't the rest fall under the same REE?

Also, what would you do in the case of the OP (where this all began) if the REE was stamped on the tank?

 

[Tracy]

@Tracy Thank you for that. Just to clarify, don't all PST 72s have the same REE? Basically, once the REE has been determined, don't the rest fall under the same REE?

Also, what would you do in the case of the OP (where this all began) if the REE was stamped on the tank?

Yes, all Pst 72s of a given year would be the same, and all of them would be close enough to be called the same. But they weren't the only manufacturer.

If the REE is stamped on the tank, the numbers are ran and if it qualifies for a plus, it gets one. I think it is mostly scuba shops that deal in Aluminum tanks that tend to gloss over it. All industrial bottles get a plus if they qualify. It is a requirement for a star, and no commercial entity wants to hydro every 5 years instead of 10.

 

[Tracy]

@Tracy OK Fair enough. I'm not a re-tester, so now you'll have to educate me. I have presented that poor old scan to a re-tester. While he agreed there was a misprint on it (just as you said on the 7.12 foot line) he explained it was easy enough for him to interpret-and besides, he knew the math and had done the measurements to confirm the REE was correct. Again, all Greek to me. Are you saying that is not possible? What would you tell a customer who wanted the plus rating on a PST 72?

Re the REE: If the OP's tank has the REE stamped on it, can that not be used to determine the test required to apply/not apply the + rating. If the tank does not have the REE number on it, is there a similar document that list the REE? What would you tell the OP? `

Inquiring minds want to know.

TIA

If you want to calculate your own REE. The formulas are in CGA pamphlet C-5. I attached an old copy, if you want the current pamphlet, (no change in regards to formula) you can purchase it directly from the CGA.
Once you read the steps, you will understand why it isn't something that is done by a hydro facility for a one off scuba tank.